Reporting discrepancies between the ClinicalTrials.gov results database and peer-reviewed publications

Discrepancies in the results reported for multiple sclerosis clinical trials: A comparison between ClinicalTrials.gov and peer-reviewed journals

OBJECTIVE

We aimed to compare the results of phase III and IV clinical trials examining drugs to treat multiple sclerosis (MS) registered at ClinicalTrials.gov to those published in peer-reviewed journals.

METHODS

After identifying trials registered at ClinicalTrials.gov, consecutive searches were conducted in PubMed, EMBASE and Google Scholar for matching publications. Information regarding participants and efficacy and safety results was extracted and compared. The degree of consistency was classified as 'concordant', 'discrepant' or 'not comparable'. The Kaplan-Meier method was used to model time to reporting.

RESULTS

In total, 65 trials were appraised. The median time from completion to reporting was shorter for ClinicalTrials.gov (16.4 vs 27.3 months; p = 0.010). Information availability was generally higher in journals except for serious adverse events (SAEs) (86.2% vs 100.0%, p = 0.029) and their description (78.2% vs 100.0%, p < 0.001). However, 45 trials had at least one reporting discrepancy (69.2%). Three studies omitted one or more primary outcomes in the matching journal publication. Regarding safety results, the lowest consistencies were found for causes of death (60.0%) and description of SAEs (27.9%).

CONCLUSION

Consulting both ClinicalTrials.gov and journals increases the accessibility to MS clinical trial results. Some data were frequently missing or disagreed between sources, raising concerns about transparency and generalizability of results.

Evidence-b(i)ased practice: Selective and inadequate reporting in early childhood autism intervention research

LAY ABSTRACT

When researchers fail to report their findings or only report some of their findings, it can make it difficult for clinicians to provide effective intervention recommendations. However, no one has examined whether this is a problem in studies of early childhood autism interventions. We studied how researchers that study early childhood autism interventions report their findings. We found that most researchers did not register their studies when they were supposed to (before the start of the study), and that many researchers did not provide all of the needed information in the registration. We also found that researchers frequently did not publish their findings when their studies were complete. When we looked at published reports, we found that many of the studies did not report enough information, and that many studies were reported differently from their registrations, suggesting that researchers were selectively reporting positive outcomes and ignoring or misrepresenting less positive outcomes. Because we found so much evidence that researchers are failing to report their findings quickly and correctly, we suggested some practical changes to make it better.

Venetoclax adverse event monitoring: a safety meta-analysis of randomized controlled trials and a retrospective evaluation of the FAERS

Concerns persist about venetoclax's long-term safety in larger populations, with limited evidence of infrequent and delayed adverse events (AEs). The study integrated safety data on venetoclax in leukemia patients from randomized controlled trials (RCTs) and FDA adverse event monitoring system (FAERS). We systematically reviewed RCTs reporting safety outcomes of venetoclax in adult leukemia patients of any gender, either monotherapy or in combination, applying advanced search on databases like PubMed, EMBASE, and ClinicalTrial.gov. The quality assessment was done using the Cochrane Risk of Bias Tool. We utilized a random effect meta-analysis to calculate risk ratio (RR) with 95% confidence intervals (CI). The Open Vigil 2.1 MedDRAv24 was used to search the FAERS database, with data available until September 2023. The disproportionality was calculated using the proportional reporting ratio and the reporting odds ratio. The study protocol for meta-analysis was registered with PROSPERO; CRD42022378006. For the safety meta-analysis, seven RCTs with available AEs were examined. A total of 942 AEs were found associated with the venetoclax group; 79% of them were in grade three or above. Venetoclax significantly increased the risk of neutropenia grade three or above (RR = 1.34, 95% CI: 1.10-1.64, p: 0.0033) compared with the control group. In FAERS, 26,436 patients were reported with AEs associated with venetoclax. Significant signal scores were observed in hematological, cardiac, vascular, and gastrointestinal disorders. 11 out of 30 generated signals, failed to meet the signal criteria upon refinement. The current study updated and improved the safety profile of venetoclax in the post-marketing period, assisting in risk evaluation and mitigation for the best possible patient health care.

Quality of reporting and concordance between sources of adverse events in the treatment of moderate-to-severe psoriasis: a cross-sectional study of RCTs from a Cochrane systematic review

OBJECTIVES

Incomplete reporting of safety outcomes in quality and availability of safety reporting in published articles of randomized controlled trials (RCTs) were described in different medical areas. The number of RCTs assessing systemic treatments for psoriasis has increased considerably. Complete and precise reporting of safety is mandatory for the efficacy/harms balance evaluation. We aimed to assess the quality and availability of safety reporting in published RCTs assessing systemic treatments for psoriasis, as well as the concordance of data between published trials and ClinicalTrials.gov (CT).

STUDY DESIGN AND SETTING

We included all RCTs in adults initiated after September 2009, assessing systemic psoriasis treatments compared with placebo or with an active comparator. All trials were selected in duplicate by 2 independent authors from the latest search of the dedicated Cochrane review. We described quality of safety reporting for all published RCTs, using a modified Consolidated Standards of Reporting Trials harms scale by using descriptive analysis, and a composite score of 3 key items of safety report. For each RCT, data on adverse events (AEs)/serious AEs (SAEs) were extracted from the publication and CT: total number of AEs/SAEs, patients with AEs/SAEs, SAEs by system organ class classification and deaths. These data were compared between sources for each RCT.

RESULTS

In total, 128 trials were included in the analysis of reporting quality, and 76 in the analysis of data concordance between sources. The median number of reported Consolidated Standards of Reporting Trials harms items per article was 9 out of 18 (IQR 7-10), and mean number was 8.39 (SD = 3.02). Items in the methods section were the least frequently reported. The proportion of RCTs reporting the number of SAEs and death were significantly higher on CT than in the published article ((100% (76/76) vs 88.2%, McNemar test, P < .0016). At least 1 discrepancy between sources for SAE safety data was found in 30/76 (39.5%) RCTs.

CONCLUSION

Shortcomings and gaps in the quality of safety reporting in publications of RCTs of systemic psoriasis treatments have been identified. A lack of data in published articles and discrepancies between published articles and CT data complete this finding.

Critical importance of correctly defining and reporting secondary endpoints when assessing the ethics of research biopsies

This article reviews the implementation challenges to the American Society of Clinical Oncology's ethical framework for including research biopsies in oncology clinical trials. The primary challenges to implementation relate to the definitions of secondary endpoints, the scientific and regulatory framework, and the incentive structure that encourages inclusion of biopsies. Principles of research stewardship require that the clinical trials community correctly articulate the scientific goals of any research biopsies, especially those that are required for the patient to enroll on a trial and receive an investigational agent. Furthermore, it is important to sufficiently justify the characterization of secondary (as distinguished from exploratory) endpoints, protect the interest of research participants, and report accurate and complete information to ClinicalTrials.gov and the published literature.

Pneumonitis After Chemoradiotherapy and Adjuvant Durvalumab in Stage III Non-Small Cell Lung Cancer

PURPOSE

Adjuvant durvalumab after definitive chemoradiotherapy (CRT) for unresectable stage III non-small cell lung cancer (NSCLC) is well-tolerated in clinical trials. However, pneumonitis rates outside of clinical trials remain poorly defined with CRT followed by durvalumab. We aimed to describe the influence of durvalumab on pneumonitis rates among a large cohort of patients with stage III NSCLC.

METHODS AND MATERIALS

We studied patients with stage III NSCLC in the national Veterans Health Administration from 2015 to 2021 who received concurrent CRT alone or with adjuvant durvalumab. We defined pneumonitis as worsening respiratory symptoms with radiographic changes within 2 years of CRT and graded events according to National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03. We used Cox regression to analyze risk factors for pneumonitis and the effect of postbaseline pneumonitis on overall survival.

RESULTS

Among 1994 patients (989 CRT alone, 1005 CRT followed by adjuvant durvalumab), the 2-year incidence of grade 2 or higher pneumonitis was 13.9% for CRT alone versus 22.1% for CRT plus durvalumab (unadjusted P < .001). On multivariable analysis, durvalumab was associated with higher risk of grade 2 pneumonitis (hazard ratio, 1.45; 95% CI, 1.09-1.93; P = .012) but not grade 3 to 5 pneumonitis (P = .2). Grade 3 pneumonitis conferred worse overall survival (hazard ratio, 2.51; 95% CI, 2.06-3.05; P < .001) but grade 2 pneumonitis did not (P = .4).

CONCLUSIONS

Adjuvant durvalumab use was associated with increased risk of low-grade but not higher-grade pneumonitis. Reassuringly, low-grade pneumonitis did not increase mortality risk. We observed increased rates of high-grade pneumonitis relative to clinical trials; the reasons for this require further study.

Overcoming publication and dissemination bias in infectious diseases clinical trials

Non-timely reporting, selective reporting, or non-reporting of clinical trial results are prevalent and serious issues. WHO mandates that summary results be available in registries within 12 months of study completion and published in full text within 24 months. However, only a limited number of clinical trials in infectious diseases, including those done during the COVID-19 pandemic, have their results posted on ClinicalTrials.gov. An analysis of 50 trials of eight antiviral drugs tested against COVID-19 with a completion date of at least 2 years ago revealed that only 18% had their results published in the registry, with 40% not publishing any results. Non-timely and non-reporting practices undermine patient participation and are ethically unacceptable. Strategies should include obligatory reporting of summary results within 12 months in clinical trial registries, with progress towards peer-reviewed publication within 24 months indicated. Timely publication of research papers should be encouraged through an automated flagging mechanism in clinical trial registries that draws attention to the status of results reporting, such as a green tick for trials that have reported summary results within 12 months and a red tick in case of failure to do so. We propose the inclusion of mandatory clinical trial reporting standards in the International Conference on Harmonization Good Clinical Practice guidelines, which should prohibit sponsor contract clauses that restrict reporting (referred to as gag clauses) and require timely reporting of results as part of the ethics committees' clearance process for clinical trial protocols.

Availability of results of clinical trials registered on EU Clinical Trials Register: cross sectional audit study

Objective

To identify the availability of results for trials registered on the European Union Clinical Trials Register (EUCTR) compared with other dissemination routes to understand its value as a results repository.

Design

Cross sectional audit study.

Setting

EUCTR protocols and results sections, data extracted 1-3 December 2020.

Population

Random sample of 500 trials registered on EUCTR with a completion date of more than two years from the beginning of searches (ie, 1 December 2018).

Main outcome measures

Proportion of trials with results across the examined dissemination routes (EUCTR, ClinicalTrials.gov, ISRCTN registry, and journal publications), and for each dissemination route individually. Prespecified secondary outcomes were number and proportion of unique results, and the timing of results, for each dissemination route.

Results

In the sample of 500 trials, availability of results on EUCTR (53.2%, 95% confidence interval 48.8% to 57.6%) was similar to the peer reviewed literature (58.6%, 54.3% to 62.9%) and exceeded the proportion of results available on other registries with matched records. Among the 383 trials with any results, 55 (14.4%, 10.9% to 17.9%) were only available on EUCTR. Also, after the launch of the EUCTR results database, median time to results was fastest on EUCTR (1142 days, 95% confidence interval 812 to 1492), comparable with journal publications (1226 days, 1074 to 1551), and exceeding ClinicalTrials.gov (3321 days, 1653 to undefined). For 117 trials (23.4%, 19.7% to 27.1%), however, results were published elsewhere but not submitted to the EUCTR registry, and no results were located in any dissemination route for 117 trials (23.4%, 19.7% to 27.1).

Conclusions

EUCTR should be considered in results searches for systematic reviews and can help researchers and the public to access the results of clinical trials, unavailable elsewhere, in a timely way. Reporting requirements, such as the EU's, can help in avoiding research waste by ensuring results are reported. The registry's true value, however, is unrealised because of inadequate compliance with EU guidelines, and problems with data quality that complicate the routine use of the registry. As the EU transitions to a new registry, continuing to emphasise the importance of EUCTR and the provision of timely and complete data is critical. For the future, EUCTR will still hold important information from the past two decades of clinical research in Europe. With increased efforts from sponsors and regulators, the registry can continue to grow as a source of results of clinical trials, many of which might be unavailable from other dissemination routes.

A Novel Method for Deriving Adverse Event Prevalence in Randomized Controlled Trials: Potential for Improved Understanding of Benefit-Risk Ratio and Application to Drug Labels

INTRODUCTION

Adverse event (AE) data in randomized controlled trials (RCTs) allow quantification of a drug's safety risk relative to placebo and comparison across medications. The standard US label for Food and Drug Administration-approved drugs typically lists AEs by MedDRA Preferred Term that occur at ≥ 2% in drug and with greater incidence than in placebo. We suggest that the drug label can be more informative for both patients and physicians if it includes, in addition to AE incidence (percent of subjects who reported the AE out of the total subjects in treatment), the absolute prevalence (percent of subject-days spent with an AE out of the total subject-days spent in treatment) and expected duration (days required for AE incidence to be reduced by half). We also propose a new method to analyze AEs in RCTs using drug-placebo difference in AE prevalence to improve safety signal detection.

METHODS

AE data from six RCTs in schizophrenia were analyzed (five RCTs of the dopamine D2 receptor-based antipsychotic lurasidone and one RCT of the novel trace amine-associated receptor 1 [TAAR1] agonist ulotaront). We determined incidence, absolute prevalence, and expected duration of AEs for lurasidone and ulotaront vs respective placebo. We also calculated areas under the curve of drug-placebo difference in AE prevalence and mean percent contribution of each AE to this difference.

RESULTS

A number of AEs with the same incidence had different absolute prevalence and expected duration. When accounting for these two parameters, AEs that did not appear in the 2% incidence tables of the drug label turned out to contribute substantially to drug tolerability. The percent contribution of a drug-related AE to the overall side effect burden increased the drug-placebo difference in AE prevalence, whereas the percent contribution of a placebo-related AE decreased such difference, revealing a continuum of risk between drug and placebo. AE prevalence curves for drug were generally greater than those for placebo. Ulotaront exhibited a small drug-placebo difference in AE prevalence curves due to a relatively low incidence and short duration of AEs in the ulotaront treatment arm as well as the emergence of disease-related AEs in the placebo arm.

CONCLUSION

Reporting AE absolute prevalence and expected duration for each RCT and incorporating them in the drug label is possible, is clinically relevant, and allows standardized comparison of medications. Our new metric, the drug-placebo difference in AE prevalence, facilitates signal detection in RCTs. We piloted this metric in RCTs of several neuropsychiatric indications and drugs, offering a new way to compare AE burden and tolerability among treatments using existing clinical trial information.

Tauro-Urso-Deoxycholic Acid Trials in Amyotrophic Lateral Sclerosis: What is Achieved and What to Expect

Phase II studies on tauro-urso-deoxycholic acid (TUDCA) raised the promise of safety and efficacy in patients with amyotrophic lateral sclerosis, a currently incurable and devastating disease. We review the available evidence on the efficacy and safety of TUDCA, administered alone or in combination, by analyzing and comparing published and ongoing studies on amyotrophic lateral sclerosis. Two independent phase II studies (using TUDCA solo or combined with sodium phenylbutyrate) showed similar efficacy in slowing disease progression measured by functional scales. One open-label follow-up TUDCA+sodium phenylbutyrate study suggested a benefit on survival. Two subsequent phase III studies with TUDCA (solo or combined with sodium phenylbutyrate) have been initiated and are currently ongoing. Their completion is expected by the end of 2023 and beginning of 2024. Evidence collected by phase II studies indicates that there are no safety concerns in patients with amyotrophic lateral sclerosis. The efficacy shown in phase II studies was considered sufficient to grant approval in some countries but not in others, owing to discrepant views on the strength of evidence. It will be necessary to wait for the results of ongoing phase III studies to attain a full appreciation of these data.

Dissemination of Registered COVID-19 Clinical Trials (DIRECCT): a cross-sectional study

BACKGROUND

The results of clinical trials should be completely and rapidly reported during public health emergencies such as COVID-19. This study aimed to examine when, and where, the results of COVID-19 clinical trials were disseminated throughout the first 18 months of the pandemic.

METHODS

Clinical trials for COVID-19 treatment or prevention were identified from the WHO ICTRP database. All interventional trials with a registered completion date ≤ 30 June 2021 were included. Trial results, published as preprints, journal articles, or registry results, were located using automated and manual techniques across PubMed, Google Scholar, Google, EuropePMC, CORD-19, the Cochrane COVID-19 Study Register, and clinical trial registries. Our main analysis reports the rate of dissemination overall and per route, and the time from registered completion to results using Kaplan-Meier methods, with additional subgroup and sensitivity analyses reported.

RESULTS

Overall, 1643 trials with completion dates ranging from 46 to 561 days prior to the start of results searches were included. The cumulative probability of reporting was 12.5% at 3 months from completion, 21.6% at 6 months, and 32.8% at 12 months. Trial results were most commonly disseminated in journals (n = 278 trials, 69.2%); preprints were available for 194 trials (48.3%), 86 (44.3%) of which converted to a full journal article. Trials completed earlier in the pandemic were reported more rapidly than those later in the pandemic, and those involving ivermectin were more rapidly reported than other common interventions. Results were robust to various sensitivity analyses except when considering only trials in a "completed" status on the registry, which substantially increased reporting rates. Poor trial registry data on completion status and dates limits the precision of estimates.

CONCLUSIONS

COVID-19 trials saw marginal increases in reporting rates compared to standard practice; most registered trials failed to meet even the 12-month non-pandemic standard. Preprints were common, complementing journal publication; however, registries were underutilized for rapid reporting. Maintaining registry data enables accurate representation of clinical research; failing to do so undermines these registries' use for public accountability and analysis. Addressing rapid reporting and registry data quality must be emphasized at global, national, and institutional levels.

Estimating the prevalence of discrepancies between study registrations and publications: a systematic review and meta-analyses

OBJECTIVES

Prospectively registering study plans in a permanent time-stamped and publicly accessible document is becoming more common across disciplines and aims to reduce risk of bias and make risk of bias transparent. Selective reporting persists, however, when researchers deviate from their registered plans without disclosure. This systematic review aimed to estimate the prevalence of undisclosed discrepancies between prospectively registered study plans and their associated publication. We further aimed to identify the research disciplines where these discrepancies have been observed, whether interventions to reduce discrepancies have been conducted, and gaps in the literature.

DESIGN

Systematic review and meta-analyses.

DATA SOURCES

Scopus and Web of Knowledge, published up to 15 December 2019.

ELIGIBILITY CRITERIA

Articles that included quantitative data about discrepancies between registrations or study protocols and their associated publications.

DATA EXTRACTION AND SYNTHESIS

Each included article was independently coded by two reviewers using a coding form designed for this review (osf.io/728ys). We used random-effects meta-analyses to synthesise the results.

RESULTS

We reviewed k=89 articles, which included k=70 that reported on primary outcome discrepancies from n=6314 studies and, k=22 that reported on secondary outcome discrepancies from n=1436 studies. Meta-analyses indicated that between 29% and 37% (95% CI) of studies contained at least one primary outcome discrepancy and between 50% and 75% (95% CI) contained at least one secondary outcome discrepancy. Almost all articles assessed clinical literature, and there was considerable heterogeneity. We identified only one article that attempted to correct discrepancies.

CONCLUSIONS

Many articles did not include information on whether discrepancies were disclosed, which version of a registration they compared publications to and whether the registration was prospective. Thus, our estimates represent discrepancies broadly, rather than our target of undisclosed discrepancies between prospectively registered study plans and their associated publications. Discrepancies are common and reduce the trustworthiness of medical research. Interventions to reduce discrepancies could prove valuable.

REGISTRATION

osf.io/ktmdg. Protocol amendments are listed in online supplemental material A.

Frequency of multiple changes to prespecified primary outcomes of clinical trials completed between 2009 and 2017 in German university medical centers: A meta-research study

BACKGROUND

Clinical trial registries allow assessment of deviations of published trials from their protocol, which may indicate a considerable risk of bias. However, since entries in many registries can be updated at any time, deviations may go unnoticed. We aimed to assess the frequency of changes to primary outcomes in different historical versions of registry entries, and how often they would go unnoticed if only deviations between published trial reports and the most recent registry entry are assessed.

METHODS AND FINDINGS

We analyzed the complete history of changes of registry entries in all 1746 randomized controlled trials completed at German university medical centers between 2009 and 2017, with published results up to 2022, that were registered in ClinicalTrials.gov or the German WHO primary registry (German Clinical Trials Register; DRKS). Data were retrieved on 24 January 2022. We assessed deviations between registry entries and publications in a random subsample of 292 trials. We determined changes of primary outcomes (1) between different versions of registry entries at key trial milestones, (2) between the latest registry entry version and the results publication, and (3) changes that occurred after trial start with no change between latest registry entry version and publication (so that assessing the full history of changes is required for detection of changes). We categorized changes as major if primary outcomes were added, dropped, changed to secondary outcomes, or secondary outcomes were turned into primary outcomes. We also assessed (4) the proportion of publications transparently reporting changes and (5) characteristics associated with changes. Of all 1746 trials, 23% (n = 393) had a primary outcome change between trial start and latest registry entry version, with 8% (n = 142) being major changes, that is, primary outcomes were added, dropped, changed to secondary outcomes, or secondary outcomes were turned into primary outcomes. Primary outcomes in publications were different from the latest registry entry version in 41% of trials (120 of the 292 sampled trials; 95% confidence interval (CI) [35%, 47%]), with major changes in 18% (54 of 292; 95% CI [14%, 23%]). Overall, 55% of trials (161 of 292; 95% CI [49%, 61%]) had primary outcome changes at any timepoint over the course of a trial, with 23% of trials (67 of 292; 95% CI [18%, 28%]) having major changes. Changes only within registry records, with no apparent discrepancy between latest registry entry version and publication, were observed in 14% of trials (41 of 292; 95% CI [10%, 19%]), with 4% (13 of 292; 95% CI [2%, 7%]) being major changes. One percent of trials with a change reported this in their publication (2 of 161 trials; 95% CI [0%, 4%]). An exploratory logistic regression analysis indicated that trials were less likely to have a discrepant registry entry if they were registered more recently (odds ratio (OR) 0.74; 95% CI [0.69, 0.80]; p<0.001), were not registered on ClinicalTrials.gov (OR 0.41; 95% CI [0.23, 0.70]; p = 0.002), or were not industry-sponsored (OR 0.29; 95% CI [0.21, 0.41]; p<0.001). Key limitations include some degree of subjectivity in the categorization of outcome changes and inclusion of a single geographic region.

CONCLUSIONS

In this study, we observed that changes to primary outcomes occur in 55% of trials, with 23% trials having major changes. They are rarely transparently reported in the results publication and often not visible in the latest registry entry version. More transparency is needed, supported by deeper analysis of registry entries to make these changes more easily recognizable. Protocol registration: Open Science Framework (https://osf.io/t3qva; amendment in https://osf.io/qtd2b).

An observational study on the adherence to study registrations in German interventional and observational studies from various fields

Background

The registration of studies, especially in the case of clinical trials, is required by the declaration of Helsinki and the policies of various scientific journals. However, numerous analyses have found considerable discrepancies between published articles and accompanying trial registrations. The aim of this study is to assess such discrepancies for a sample of studies with recruiting locations in Germany. Additionally, the association between the adherence to registrations and possible involvement of Coordinating Centers for Clinical Studies (KKS) as well as Universities of Excellence was tested.

Methods

For a sample of 376 interventional or observational study registrations, we found 115 published articles. Subsequently, we searched for discrepancies in the study design, the key inclusion criteria, the interventions, the blinding, and a primary and a secondary outcome.

Results

We found discrepancies in 26% of all studies, most frequently in the secondary outcomes, where 16.5% of the secondary outcomes per study that were registered in most detail had discrepancies. When running regression models for adherence discrepancies, the only variable that had a statistically significant association with better adherence was registration on ClinicalTrials.gov. The association of potential involvement of a KKS with adherence ratings was positive, too, but statistically insignificant.

Conclusions

In summary, the amount of discrepancies between registrations and published articles remains elevated.

The international clinical trials registry platform (ICTRP): data integrity and the trends in clinical trials, diseases, and drugs

Introduction: Clinical trials are the gold standard for testing new therapies. Databases like ClinicalTrials.gov provide access to trial information, mainly covering the US and Europe. In 2006, WHO introduced the global ICTRP, aggregating data from ClinicalTrials.gov and 17 other national registers, making it the largest clinical trial platform by June 2019. This study conducts a comprehensive global analysis of the ICTRP database and provides framework for large-scale data analysis, data preparation, curation, and filtering. Materials and methods: The trends in 689,793 records from the ICTRP database (covering trials registered from 1990 to 2020) were analyzed. Records were adjusted for duplicates and mapping of agents to drug classes was performed. Several databases, including DrugBank, MESH, and the NIH Drug Information Portal were used to investigate trends in agent classes. Results: Our novel approach unveiled that 0.5% of the trials we identified were hidden duplicates, primarily originating from the EUCTR database, which accounted for 82.9% of these duplicates. However, the overall number of hidden duplicates within the ICTRP seems to be decreasing. In total, 689 793 trials (478 345 interventional) were registered in the ICTRP between 1990 and 2020, surpassing the count of trials in ClinicalTrials.gov (362 500 trials by the end of 2020). We identified 4 865 unique agents in trials with DrugBank, whereas 2 633 agents were identified with NIH Drug Information Portal data. After the ClinicalTrials.gov, EUCTR had the most trials in the ICTRP, followed by CTRI, IRCT, CHiCTR, and ISRCTN. CHiCTR displayed a significant surge in trial registration around 2015, while CTRI experienced rapid growth starting in 2016. Conclusion: This study highlights both the strengths and weaknesses of using the ICTRP as a data source for analyzing trends in clinical trials, and emphasizes the value of utilizing multiple registries for a comprehensive analysis.

A Pilot Study on Result Reporting Rates from Clinical Trials of Regenerative Medicine

Sharing the methods and results of clinical trials with full transparency is an ethical obligation for those involved in clinical research. In this regard, ClinicalTrials.gov requires reporting of results to the registry within 1 year of completion of the trial. However, a poor result reporting rate has been pointed out, with approximately half the trial results not been reported. It has been suggested that one of the reasons behind this could be the influence of sponsors who conduct the clinical trials. In the course of our previous trend analysis on regenerative medicine for stroke (STR) using ClinicalTrials.gov and the International Clinical Trials Registry Platform (ICTRP) portal site as data sources, we suspected whether the results of gene and/or cell therapy trials are poorly reported. For this reason, a multivariate analysis using data from ClinicalTrials.gov was performed to identify the factors suppressing the result reporting rate, expanding our study to four different kinds of neurological diseases and regenerative medicine as a treatment modality when small-molecule compounds and biologics were set up as controls, in addition to the sponsor type factor. As a result, we found gene and/or cell therapy (therapeutic modality) in addition to STR (disease area), trials completed in 2005-2007, and clinical phases II and IV as independent factors that suppressed the rate of reporting results to ClinicalTrials.gov. On the other hand, big pharmaceutical companies were identified as a factor that increased the reporting result rate to ClinicalTrials.gov. When we applied result reporting publications through PubMed as an index, our study data revealed that the following factors were not identified as the cause for a decrease in the reporting result rate: STR (as disease area), trials completed between 2005 and 2007, and gene/cell therapy (as treatment modality). In this context, our findings indicate that gene/cell therapy has led to the suppression of the result reporting rate to ClinicalTrials.gov. This confirmed our initial suspicion of the low result reporting rate of gene/cell therapy trials. We believe that further studies are required to elucidate the factors affecting the result reporting rate from the perspective of disease area and treatment modality. Impact Statement Several studies have addressed the poor result reporting rate of clinical trials, which still remains an issue. Regenerative medicine holds great promise for the future and the process of its practical application is expected to be challenging. Although having a limited disease area and small sample size, to the best of our knowledge, this is the first study to point out insufficient result reporting of clinical trials of regenerative medicine from the perspective of treatment modality. This report highlights an issue for discussing the path toward its translation through an overview of various factors in comparison with conventional treatment modalities.

A comprehensive review and characterization of nasopharyngeal carcinoma clinical trials

Objective

Although standard of care for primary nasopharyngeal carcinoma (NPC) is chemoradiotherapy, there remains no consensus on management of recurrent or metastatic disease. We characterized recent clinical trials on NPC to assess trends in NPC treatment and establish promising areas for future research.

Study Design

Retrospective database study.

Setting

ClinicalTrials.gov database.

Methods

Retrospective review of all NPC trials from November 1999 to June 2021. For each study, the following variables were extracted: study characteristics, intervention, outcome measures, and inclusion criteria. Secondary searches via PubMed and Google scholar determined trial publication status.

Results

A total of 448 clinical trials were identified: 72 (16%) observational and 376 (84%) interventional, of which there were 30 (8%) Phase I, 183 (49%) Phase II, 86 Phase III (23%), and 5 (1%) Phase IV trials. Fifty-four percent of trials included only primary NPC while 111 (25%) exclusively studied recurrent cancers. The most common interventions were cisplatin (n = 64) and intensity modulated radiation therapy (n = 54); there were 38 trials involving PD-1 monoclonal antibodies. Thirty-four studies examined quality of life measures, including xerostomia and mucositis. Of the completed studies, 53.2% have published manuscripts. Poor patient accrual was the most common reason for premature study termination.

Conclusions

Novel immunotherapies have been increasingly incorporated into NPC studies in recent years, however, chemotherapy and radiation, despite their numerous side effects, are still widely used due to their clinical effectiveness. Future trials are warranted to determine the optimal therapeutic regimens to decrease relapse rates and side effects.

Current Research and Development in Hyperthermic Intraperitoneal Chemotherapy (HIPEC)-A Cross-Sectional Analysis of Clinical Trials Registered on ClinicalTrials.gov

INTRODUCTION

Over the past two decades, cytoreductive surgery and HIPEC has improved outcomes for selected patients with peritoneal metastasis from various origins. This is a cross-sectional study with descriptive analyses of HIPEC trials registered on ClinicalTrials.gov. This study aimed to characterize clinical trials on HIPEC registered on ClinicalTrials.gov with the primary objective of identifying a trial focus and to examine whether trial results were published.

METHODS

The search included trials registered from 1 January 2001 to 14 March 2022. We examined the associations of exposure variables and other trial features with two primary outcomes: therapeutic focus and results reporting.

RESULTS

In total, 234 clinical trials were identified; 26 (11%) were already published, and 15 (6%) trials have reported their results but have not been published as full papers. Among ongoing nonpublished trials, 81 (39%) were randomized, 30 (14%) were blinded, n = 39 (20%) were later phase trials (i.e., phases 3 and 4), n = 152 (73%) were from a single institution, and 91 (44%) had parallel groups. Most of the trials were recruiting at the time of this analysis (75, 36%), and 39 (20%) were completed but had yet to publish results. In total, 68% of the trials focused on treatment strategies, and 53% investigated the oncological outcome. The most studied neoplasms for HIPEC trials were peritoneally metastasized colorectal cancer (32%), gastric cancer (29%), and ovarian cancer (26%). Twenty different drugs were analyzed in these clinical trials.

CONCLUSIONS

Many study results are awaited from ongoing HIPEC trials. Most HIPEC trials focused on gastric, colorectal, or ovarian cancer. Many clinical trials were identified involving multiple entities and chemotherapeutic agents.

Atrial Fibrillation Incidence Associated With Exposure to Anticancer Drugs Used as Monotherapy in Clinical Trials

Background

The incidence of atrial fibrillation (AF) associated with anticancer drugs in cancer patients remains incompletely defined.

Objectives

The primary outcome was the annualized incidence rate of AF reporting associated with exposure to 1 of 19 anticancer drugs used as monotherapy in clinical trials. The authors also report the annualized incidence rate of AF reported in the placebo arms of these trials.

Methods

The authors systematically searched ClinicalTrials.gov for phase 2 and 3 cancer trials studying 19 different anticancer drugs of interest used as monotherapy, up to September 18, 2020. The authors performed a random-effects meta-analysis to compute summary AF annualized incidence rate with its 95% CI using log transformation and inverse variance weighting.

Results

A total of 191 clinical trials (47.1% were randomized) of 16 anticancer drugs across 26,604 patients were included. Incidence rates could be calculated for 15 drugs administered singly as monotherapy. Summary annualized incidence rates of AF reporting associated with exposure to 1 of the 15 anticancer drugs used as monotherapy were derived; these ranged from 0.26 to 4.92 per 100 person-years. The 3 highest annualized incidence rates of AF reporting were found for ibrutinib 4.92 (95% CI: 2.91-8.31), clofarabine 2.38 (95% CI: 0.66-8.55), and ponatinib 2.35 (95% CI: 1.78-3.12) per 100 person-years. Summary annualized incidence rate of AF reporting in the placebo arms was 0.25 per 100 person-years (95% CI: 0.10-0.65).

Conclusions

AF reporting is not a rare event associated with anticancer drugs in clinical trials. A systematic and standardized AF detection should be considered in oncological trials, particularly those studying anticancer drugs associated with high AF rates. (Incidence of atrial fibrillation associated with anticancer drugs exposure in monotherapy, A safety meta-analysis of phase 2 and 3 clinical trials; CRD42020223710).

Analysis of Rates of Completion, Delays, and Participant Recruitment in Randomized Clinical Trials in Surgery

IMPORTANCE

Discontinuation and nonpublication are established sources of avoidable waste among surgical trials, but rates of delayed completion and recruiting shortfalls remain unclear.

OBJECTIVES

To examine the rate of delayed completion, incomplete enrollment, and discontinuation among randomized clinical trials in surgical populations and the duration of delays and extent of recruiting shortfalls among these trials.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study examined randomized clinical trials in surgical populations registered on ClinicalTrials.gov between January 1, 2010, and December 31, 2014. Analysis was conducted between October 27, 2021, and June 30, 2022.

MAIN OUTCOMES AND MEASURES

The main outcomes were the percentages of trials completed on time or with full enrollment. Delays and recruiting shortfalls were identified by comparing projected enrollment and study timeframes prespecified at the time of registration with the actual study duration and enrollment reported on completion or discontinuation. Absolute and relative differences between planned and actual trial conduct were presented for discontinued trials and those completed with delays or recruiting shortfalls.

RESULTS

In total, 2542 randomized clinical trials in surgical populations were included in the study sample, of which 370 (14.6%; 95% CI, 13.2%-15.9%) were completed both on time and with full enrollment. Approximately 1 in 5 trials (20.4%; 95% CI, 18.9%-22.0%) were completed within their planned timeframe, and 1166 trials (45.9%; 95% CI, 43.9%-47.8%) met their prespecified enrollment target. The median delay among completed trials was 12.2 months (IQR, 5.1-24.3 months) or 66.7% (IQR, 30.1%-135.8%) longer than planned. Among completed trials that did not meet their prespecified enrollment target, the median recruiting shortfall was equivalent to 31.0% (IQR, 12.7%-55.5%) of the planned study sample. A total of 546 trials (21.5%; 95% CI, 19.9%-23.1%) were discontinued. The median time to discontinuation was 26.4 months (IQR, 15.2-45.7 months), and the median recruiting shortfall among discontinued trials was equivalent to 92.7% (IQR, 65.0%-100.0%) of the trial's prespecified enrollment target.

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that delayed completion, recruiting shortfalls, and untimely discontinuation were common among surgical trials. These findings highlight the importance of ensuring that investigators and funders do not overestimate the feasibility of planned trials.

Sex, Racial, and Ethnic Representation in COVID-19 Clinical Trials: A Systematic Review and Meta-analysis

Importance

Since the onset of the COVID-19 pandemic, there have been calls for COVID-19 clinical trials to be fully representative of all demographic groups. However, limited evidence is available about the sex, racial, and ethnic representation among COVID-19 prevention and treatment trials.

Objective

To investigate whether female participants and racial and ethnic minority individuals are adequately represented in COVID-19 prevention and treatment trials in the US.

Data Sources

Identified studies were registered on ClinicalTrials.gov or published in the PubMed database from October 2019 to February 2022.

Study Selection

Included studies must have provided the number of enrolled participants by sex, race, or ethnicity. Only interventional studies conducted in the US for the primary purpose of the diagnosis, prevention, or treatment of (or supportive care for) COVID-19 conditions were included.

Data Extraction and Synthesis

Data on counts of enrollments by demographic variables (sex, race, and ethnicity) and location (country and state) were abstracted. Studies were broadly categorized by primary purpose as prevention (including vaccine and diagnosis studies) vs treatment (including supportive care studies). A random effects model for single proportions was used. Trial estimates were compared with corresponding estimates of representation in the US population with COVID-19.

Main Outcomes and Measures

Sex, racial, and ethnic representation in COVID-19 clinical trials compared with their representation in the US population with COVID-19.

Results

Overall, 122 US-based COVID-19 clinical trials comprising 176 654 participants were analyzed. Studies were predominantly randomized trials (n = 95) for treatment of COVID-19 (n = 103). Sex, race, and ethnicity were reported in 109 (89.3%), 95 (77.9%), and 87 (71.3%) trials, respectively. Estimated representation in prevention and treatment trials vs the US population with COVID-19 was 48.9% and 44.6% vs 52.4% for female participants; 23.0% and 36.6% vs 17.7% for Hispanic or Latino participants; 7.2% and 16.5% vs 14.1% for Black participants; 3.8% and 4.6% vs 3.7% for Asian participants; 0.2% and 0.9% vs 0.2% for Native Hawaiian or Other Pacific Islander participants; and 1.3% and 1.4% vs 1.1% for American Indian or Alaska Native participants. Compared with expected rates in the COVID-19 reference population, female participants were underrepresented in treatment trials (85.1% of expected; P < .001), Black participants (53.7% of expected; P = .003) and Asian participants (64.4% of expected; P = .003) were underrepresented in prevention trials, and Hispanic or Latino participants were overrepresented in treatment trials (206.8% of expected; P < .001).

Conclusions and Relevance

In this systematic review and meta-analysis, aggregate differences in representation for several demographic groups in COVID-19 prevention and treatment trials in the US were found. Strategies to better ensure diverse representation in COVID-19 studies are needed, especially for prevention trials.

E-cigarette manufacturers' compliance with clinical trial reporting expectations: a case series of registered trials by Juul Labs

BACKGROUND

Electronic cigarettes (e-cigarettes) are a frequently debated topic in public health. It is essential that clinical trials examining e-cigarettes are fully and accurately reported, especially given long-standing concerns about tobacco industry research. We assess the reporting of clinical trials sponsored by Juul Labs, the largest e-cigarette company in the USA, against accepted reporting standards.

METHODS

We searched ClinicalTrials.gov for all trials sponsored by Juul Labs and determined those with registry data consistent with coverage by the Food and Drug Administration (FDA) Amendments Act 2007 (FDAAA). For trials with a primary completion date more than 1 year earlier, we searched ClinicalTrials.gov, the academic literature and a Juul-funded research database (JLI Science) for results. For located results, we compared reported outcomes with registered outcomes in line with Consolidated Standards of Reporting Trials (CONSORT) reporting guidelines.

RESULTS

We located five registered trials sponsored by Juul Labs that appeared covered by the FDAAA 2007 in the public data. All five trials did not have results available on ClinicalTrials.gov. We found one publication and four poster presentations reporting results for four of the five covered trials outside of ClinicalTrials.gov. Of 61 specified outcomes, 28 were CONSORT compliant. Specific outcome reporting issues are detailed.

DISCUSSION

Our findings raise substantial concerns regarding these trials. Clinicians, public health professionals, and the public cannot make informed choices about the benefits or hazards of e-cigarettes if the results of clinical trials are not completely and transparently reported. Clarification and potential enforcement of reporting laws may be required.

Reducing bias, increasing transparency and calibrating confidence with preregistration

Flexibility in the design, analysis and interpretation of scientific studies creates a multiplicity of possible research outcomes. Scientists are granted considerable latitude to selectively use and report the hypotheses, variables and analyses that create the most positive, coherent and attractive story while suppressing those that are negative or inconvenient. This creates a risk of bias that can lead to scientists fooling themselves and fooling others. Preregistration involves declaring a research plan (for example, hypotheses, design and statistical analyses) in a public registry before the research outcomes are known. Preregistration (1) reduces the risk of bias by encouraging outcome-independent decision-making and (2) increases transparency, enabling others to assess the risk of bias and calibrate their confidence in research outcomes. In this Perspective, we briefly review the historical evolution of preregistration in medicine, psychology and other domains, clarify its pragmatic functions, discuss relevant meta-research, and provide recommendations for scientists and journal editors.

Reporting of the safety from allergic rhinitis trials registered on ClinicalTrials.gov and in publications: An observational study

BACKGROUND

Incomplete and inconsistent reporting of adverse events (AEs) through multiple sources can distort impressions of the overall safety of the medical interventions examined as well as the benefit-risk relationship. We aimed to assess completed allergic rhinitis (AR) trials registered in ClinicalTrials.gov for completeness and consistency of AEs reporting comparing ClinicalTrials.gov and corresponding publications.

METHODS

We retrospectively examined completed randomised controlled trials on AR registered in ClinicalTrials.gov on or after 9/27/2009 to trials updated with results on or before 12/31/2021 along with any corresponding publications. Complete reporting of AEs in ClinicalTrials.gov were summarised in tables describing AE information, and complete reporting in publications was an explicit statement of serious AE, death or other AE. Difference in completeness, number, or description of AEs between ClinicalTrials.gov and publication was classified as inconsistent reporting of AEs.

RESULTS

There were 99 registered trials with 45 (45.5%) available publications. All published trials completely reported AEs in ClinicalTrials.gov, and 21 (46.7%) in publications (P < .001). In 43 (95.6%) publications, there was at least one inconsistency in the reporting of AEs (P < .001). 8 (17.8%) publications had different number of serious AEs (P = .003), 36 (80.0%) of other AEs (P < .001) while deaths reporting was inconsistent in 8 (57.1%) publications (P = .127).

CONCLUSION

The reporting of AEs from AR trials is complete in ClinicalTrials.gov and incomplete and inconsistent in corresponding publications. There is a need to improve the reporting of AEs from AR trials in corresponding publications, and thus to improve patient safety.

Race/ethnicity reporting and representation in US clinical trials: a cohort study

BACKGROUND

Systemic progress in improving trial representation is uncertain, and previous analyses of minority trial participation have been limited to small cohorts with limited exploration of driving factors.

METHODS

We analyzed detailed trial records from all US clinical trials registered in ClinicalTrials.gov from March 2000 to March 2020. Minority enrollment was compared to 2010 US Census demographic estimates using Wilcoxon test. We utilized logistic regression and generalized linear regression with a logit link to assess the association of possible drivers (including trials' funding source, size, phase, and design) with trials' disclosure of and amount of minority enrollment respectively.

FINDINGS

Among 20,692 US-based trials with reported results (representing ~4·76 million enrollees), only 43% (8,871/20,692) reported any race/ethnicity data. The majority of enrollees were White (median 79·7%; interquartile range [IQR] 61·9-90·0%), followed by Black (10·0%; IQR 2·5-23·5%), Hispanic/Latino (6·0%; IQR 0·43-15·4%), Asian (1·0%; IQR 0·0-4·1%), and American Indian (0·0%; IQR 0·0-0·2%). Median combined enrollment of minority race/ethnicity groups (Black, Hispanic/Latino, Asian, American Indian, Other/Multi) was below census estimates (27·6%) (p<0·001) however increased at an annual rate of 1·7%. Industry and Academic funding were negatively associated with race/ethnicity reporting (Industry adjusted odds ratio [aOR]: 0·42, 95% confidence interval [CI]: 0·38 to 0·46, p<0.0001; Academic aOR: 0·45, CI: 0·41 to 0·50, p<0.0001). Industry also had a negative association with the proportion of minority ethnicity enrollees (aOR: 0·69, CI: 0·60 to 0·79) compared to US Government-funded trials.

INTERPRETATION

Over the past two decades, the majority of US trials in ClinicalTrials.gov do not report race/ethnicity enrollment data, and minorities are underrepresented in trials with modest improvement over time.

FUNDING

Stanford Medical Scholars Research Funding, the National Heart, Lung, and Blood Institute, NIH (1K01HL144607) and the American Heart Association/Robert Wood Johnson Medical Faculty Development Program.

Risk of Thromboembolic Events in Cancer Patients Treated with Immune Checkpoint Inhibitors: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

 The association between immune checkpoint inhibitors (ICIs) and thromboembolic events (TEEs) remains controversial.

OBJECTIVE

 The goal of this study was to assess the risk of major TEEs associated with ICIs.

METHODS

 We explored ICI-related TEEs in randomized controlled trials available in ClinicalTrials.gov and electronic databases up to June 30, 2021. Meta-analysis was performed by using Peto odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

 A total of 61 studies were included. Patients treated with ICIs had a similar risk of venous thromboembolism (VTE) but a significantly increased risk of arterial thromboembolism (ATE) (Peto OR: 1.58 [95% CI: 1.21-2.06]) compared with non-ICI regimens. Stratified by different regimens, only PD-L1 (programmed cell death ligand 1) inhibitors showed a significant increase in ATE (Peto OR: 2.07 [95% CI: 1.26-3.38]). The incidence of VTE was higher in PD-1/PD-L1 inhibitor and CTLA-4 (cytotoxic T lymphocyte antigen 4) inhibitor combination therapies compared with monotherapies (Peto OR: 2.23 [95% CI: 1.47-3.37]). Stratified by tumor, for pulmonary embolism (PE) and cerebral ATE, the statistically significant results were only seen in lung cancer patients (Peto OR: 1.42 [95% CI: 1.02-1.97]; Peto OR: 2.10 [1.07-4.12]), and for myocardial infarction, the statistically significant result was only seen in other tumor types (Peto OR: 2.66 [95% CI: 1.68-4.20], p < 0.0001).

CONCLUSION

 There was no significant increase in the overall risk of VTE in patients treated with ICIs; however, special attention should be given to the risk of VTE in PD-1/PD-L1 inhibitor and CTLA-4 inhibitor combination therapy and PE in lung cancer patients. PD-L1 inhibitors were associated with a significant increase in ATE.

Registration quality and availability of publications for clinical trials in Germany and the influence of structural factors

INTRODUCTION

Analyses of clinical trial registries (CTRs) offer insights into methodological problems of published research studies, e.g., non-publication and outcome-switching. Here, we use CTRs as a tool to evaluate clinical studies conducted in Germany and test how their registration quality is associated with time and structural factors: Coordinating Centers for Clinical Trials (KKS) and Universities of Excellence.

METHODS

We searched ClinicalTrials.gov, the DRKS, and the ICTRP for clinical trials recruiting participants in Germany. As a measure for the methodological quality, we assessed the proportion of trials that were pre-registered. In addition, the registration quality and availability of publications relating to the trials were manually assessed for a sample (n = 639). Also, the influence of the structural factors was tested using regression models.

RESULTS

We identified 35,912 trials that were conducted in Germany. 59% of trials were pre-registered. Surprisingly, Universities of Excellence had lower pre-registration rates. The influence of KKS was unclear and also difficult to test. Interventional trials were more likely to be pre-registered. Registration quality improved over time and was higher in interventional trials. As of early 2021, 49% of trials that started until the end of 2015 have published scientific articles. 187 of 502 studies on ClinicalTrials.gov for which we found published articles did not reference any in the registry entry.

DISCUSSION

The structural predictors did not show consistent relationships with the various outcome variables. However, the finding that the study type and time were related to better registration quality suggests that regulatory regimes may have an impact. Limitations of this non-pre-registered study were that no modifications to registry entries were tracked and the coarse measure of KKS involvement.

Identifying unreported links between ClinicalTrials.gov trial registrations and their published results

A substantial proportion of trial registrations are not linked to corresponding published articles, limiting analyses and new tools. Our aim was to develop a method for finding articles reporting the results of trials that are registered on ClinicalTrials.gov when they do not include metadata links. We used a set of 27,280 trial registration and article pairs to train and evaluate methods for identifying missing links in both directions-from articles to registrations and from registrations to articles. We trained a classifier with six distance metrics as feature representations to rank the correct article or registration, using recall@K to evaluate performance and compare to baseline methods. When identifying links from registrations to published articles, the classifier ranked the correct article first (recall@1) among 378,048 articles in 80.8% of evaluation cases and 34.9% in the baseline method. Recall@10 was 85.1% compared to 60.7% in the baseline. When predicting links from articles to registrations, recall@1 was 83.4% for the classifier and 39.8% in the baseline. Recall@10 was 89.5% compared to 65.8% in the baseline. The proposed method improves on our baseline document similarity method to be feasible for identifying missing links in practice. Given a ClinicalTrials.gov registration, a user checking 10 ranked articles can expect to identify the matching article in at least 85% of cases, if the trial has been published. The proposed method can be used to improve the coupling of ClinicalTrials.gov and PubMed, with applications related to automating systematic review and evidence synthesis processes.

Reporting of clinical trial safety results in ClinicalTrials.gov for FDA-approved drugs: A cross-sectional analysis

BACKGROUND

Adverse events identified during clinical trials can be important early indicators of drug safety, but complete and timely data on safety results have historically been difficult to access. The aim was to compare the availability, completeness, and concordance of safety results reported in ClinicalTrials.gov and peer-reviewed publications.

METHODS

We analyzed clinical trials used in the Food and Drug Administration safety assessment of new drugs approved between 1 July 2018 and 30 June 2019. The key safety outcomes examined were all-cause mortality, serious adverse events, adverse events, and withdrawals due to adverse events. Availability of safety results was measured by the presence and timing of a record of trial-level results in ClinicalTrials.gov and a corresponding peer-reviewed publication. For the subset of trials with available results, completeness was defined as the reporting of safety results for all participants and compared between ClinicalTrials.gov and publications. To assess concordance, we compared the numeric results for safety outcomes reported in ClinicalTrials.gov and publications to results in Food and Drug Administration trial reports.

RESULTS

Among 156 trials studying 52 drugs, 91 (58.3%) trials reported safety results in ClinicalTrials.gov and 106 (67.9%) in peer-reviewed publications (risk difference = -9.6%, 95% confidence interval = -20.3 to 1.0). All-cause mortality was reported sooner in published articles compared with ClinicalTrials.gov (log-rank test, p = 0.01). There was no difference in time to reporting for serious adverse events (p = 0.05), adverse events (p = 0.09), or withdrawals due to adverse events (p = 0.20). Complete reporting of all-cause mortality was similar in ClinicalTrials.gov and publications (74.7% vs 78.3%, respectively; risk difference = -3.6%, 95% confidence interval = -15.5 to 8.3) and higher in ClinicalTrials.gov for serious adverse events (100% vs 79.2%; risk difference = 20.8%, 95% confidence interval = 13.0 to 28.5) and adverse events (100% vs 86.8%; risk difference = 13.2%, 95% confidence interval = 6.8 to 19.7). Withdrawals due to adverse events were less often completely reported in ClinicalTrials.gov (62.6% vs 92.5%; risk difference = -29.8%, 95% confidence interval = -40.1 to -18.7). No difference was found in concordance of results between ClinicalTrials.gov and publications for all-cause mortality, serious adverse events, or withdrawals due to adverse events.

CONCLUSION

Safety results were available in ClinicalTrials.gov at a similar rate as in peer-reviewed publications, with more complete reporting of certain safety outcomes in ClinicalTrials.gov. Future efforts should consider adverse event reporting in ClinicalTrials.gov as an accessible data source for post-marketing surveillance and other evidence synthesis tasks.

A web-based tool for automatically linking clinical trials to their publications

OBJECTIVE

Evidence synthesis teams, physicians, policy makers, and patients and their families all have an interest in following the outcomes of clinical trials and would benefit from being able to evaluate both the results posted in trial registries and in the publications that arise from them. Manual searching for publications arising from a given trial is a laborious and uncertain process. We sought to create a statistical model to automatically identify PubMed articles likely to report clinical outcome results from each registered trial in ClinicalTrials.gov.

MATERIALS AND METHODS

A machine learning-based model was trained on pairs (publications known to be linked to specific registered trials). Multiple features were constructed based on the degree of matching between the PubMed article metadata and specific fields of the trial registry, as well as matching with the set of publications already known to be linked to that trial.

RESULTS

Evaluation of the model using known linked articles as gold standard showed that they tend to be top ranked (median best rank = 1.0), and 91% of them are ranked in the top 10.

DISCUSSION

Based on this model, we have created a free, public web-based tool that, given any registered trial in ClinicalTrials.gov, presents a ranked list of the PubMed articles in order of estimated probability that they report clinical outcome data from that trial. The tool should greatly facilitate studies of trial outcome results and their relation to the original trial designs.

Adverse events of immunotherapy in non-small cell lung cancer: A systematic review and network meta-analysis

BACKGROUND

Immune checkpoint inhibitors have yielded significant treatment progress in non-small cell lung cancer (NSCLC), while some special adverse events (AEs) named immune-related adverse events (irAEs) were observed in clinical trials. We aimed to systematically assess the incidences of AEs in immunotherapy of NSCLC.

METHODS

We searched randomized controlled trials (RCTs) in PubMed/MEDLINE, Embase, Cochrane, and ClinicalTrail.gov before May 2021, and grouped arms into 10 treatment categories. We extracted AEs as serious (grade 3-5) or others (grade1-2) from all systems, and we pooled their incidences by random effects model. For arm-based pair-wise comparisons, we employed Bayesian network meta-analysis. Meta-regression was used to assess the contribution of coefficients.

RESULTS

Totally 23,322 patients from 52 RCTs were included. The overall incidences of serious AEs were 37.0% in chemotherapy arm, 33.0% in PD1 arm, and 37.0% in PDL1 arm, while in combined groups it was 47.0% in PDL1_Chemo arm, 43.0% in PD1_CTLA4 arm, and 48.0% in ICI_Target arm. The incidence of each serious AE was less than 4% in monotherapy, and slightly higher in combined groups. In network meta-analysis, the immunotherapeutic groups presented a significant higher incidence rank in colitis, hepatobiliary disorders, pneumonitis, and rash compared with chemotherapy. There was a significantly positive correlation between the occurrence of serious hepatitis (p < 0.0001) and PFS in PDL1 arm, likewise serious pneumonitis (p = 0.0049) and rash (p < 0.0001) in PD1 arm.

CONCLUSIONS

The overall incidences of AEs were similar in immune monotherapy compared with chemotherapy in NSCLC. Some irAEs were more common in immune therapy and their frequencies were positively associated with clinical efficacy.

Characteristics of completed clinical trials for spinal cord injury from 1999 to 2020

Numerous clinical trials are being conducted in the field of spinal cord injury (SCI). These trials are typically registered on ClinicalTrials.gov. The objective of this study was to identify the characteristics of the completed SCI trials and characterize the potential factors associated with publication. ClinicalTrials.gov database was queried for all the completed trials on patients with SCI. Baseline characteristics of the completed trials were assessed. The publication status of these trials was identified using PubMed or Google Scholar. The secondary and primary outcomes reported in the publication were then compared to the outcomes registered in ClinicalTrial.gov. Multivariable logistic regression analysis was performed to determine the characteristics associated with publication status and time to publication. A total of 457 of 1,061 trials on SCI were completed. Of those, 60% were ultimately published. Trials that had received funding from sources besides the NIH, private industries, or the federal government were more likely to remain unpublished. The median time to publish was three years, with larger trials taking a longer time. The median sample size for completed trials was 30. Assessment of mismatch rates in primary outcomes of published data to registered outcomes was 8.9%. In SCI trials, outcomes registered on ClinicalTrial.gov often matched published results. Additionally, sample size and funding source play a significant role in the publication rate of these trials. Published data represents a reliable source for clinicians, researchers, and patients; efforts to curb publication bias and reporting bias are paramount for implementing evidence-based practices and ensure proper scientific conduct.

Clinical trial registries as Scientometric data: A novel solution for linking and deduplicating clinical trials from multiple registries

Registries of clinical trials are a potential source for scientometric analysis of medical research and serve important functions for the research community and the public at large. Clinical trials that recruit patients in Germany are usually registered in the German Clinical Trials Register (DRKS) or in international registries such as ClinicalTrials.gov. Furthermore, the International Clinical Trials Registry Platform (ICTRP) aggregates trials from multiple primary registries. We queried the DRKS, ClinicalTrials.gov, and the ICTRP for trials with a recruiting location in Germany. Trials that were registered in multiple registries were linked using the primary and secondary identifiers and a Random Forest model based on various similarity metrics. We identified 35,912 trials that were conducted in Germany. The majority of the trials was registered in multiple databases. 32,106 trials were linked using primary IDs, 26 were linked using a Random Forest model, and 10,537 internal duplicates on ICTRP were identified using the Random Forest model after finding pairs with matching primary or secondary IDs. In cross-validation, the Random Forest increased the F1-score from 96.4% to 97.1% compared to a linkage based solely on secondary IDs on a manually labelled data set. 28% of all trials were registered in the German DRKS. 54% of the trials on ClinicalTrials.gov, 43% of the trials on the DRKS and 56% of the trials on the ICTRP were pre-registered. The ratio of pre-registered studies and the ratio of studies that are registered in the DRKS increased over time.

Reliability of Trial Information Across Registries for Trials With Multiple Registrations: A Systematic Review

IMPORTANCE

Clinical trial registries are important for gaining an overview of ongoing research efforts and for deterring and identifying publication bias and selective outcome reporting. The reliability of the information in trial registries is uncertain.

OBJECTIVE

To assess the reliability of information across registries for trials with multiple registrations.

EVIDENCE REVIEW

For this systematic review, 360 protocols of randomized clinical trials (RCTs) approved by research ethics committees in Switzerland, the UK, Canada, and Germany in 2012 were evaluated. Clinical trial registries were searched from March to September 2019 for corresponding registrations of these RCTs. For RCTS that were recorded in more than 1 clinical trial registry, key trial characteristics that should be identical among all trial registries (ie, sponsor, funding source, primary outcome, target sample size, trial status, date of first patient enrollment, results available, and main publication indexed) were extracted in duplicate. Agreement between the different trial registries for these key characteristics was analyzed descriptively. Data analyses were conducted from May 1 to November 30, 2020. Representatives from clinical trial registries were interviewed to discuss the study findings between February 1 and March 31, 2021.

FINDINGS

The analysis included 197 RCTs registered in more than 1 trial registry (151 in 2 registries and 46 in 3 registries), with 188 trials in ClinicalTrials.gov, 185 in the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), 20 in ISRCTN, and 47 in other registries. The agreement of key information across all registries was as follows: 178 of 197 RCTs (90%; 95% CI, 85%-94%) for sponsor, 18 of 20 (90%; 95% CI, 68%-99%) for funding source (funding was not reported on ClinicalTrials.gov), 154 of 197 (78%; 95% CI, 72%-84%) for primary outcome, 90 of 197 (46%; 95% CI, 39%-53%) for trial status, 122 of 194 (63%; 95% CI, 56%-70%) for target sample size, and 43 of 57 (75%; 95% CI, 62%-86%) for the date of first patient enrollment when the comparison time was increased to 30 days (date of first patient enrollment was not reported on EudraCT). For results availability in trial registries, agreement was 122 of 197 RCTs (62%; 95% CI, 55%-69%) for summary data reported in the registry and 91 of 197 (46%; 95% CI, 39%-53%) for whether a published article with the main results was indexed. Different legal requirements were stated as the main reason for inconsistencies by representatives of clinical trial registries.

CONCLUSIONS AND RELEVANCE

In this systematic review, for a substantial proportion of registered RCTs, information about key trial characteristics was inconsistent across trial registries, raising concerns about the reliability of the information provided in these registries. Further harmonization across clinical trial registries may be necessary to increase their usefulness.

Prospective adverse event risk evaluation in clinical trials

Proactive and objective regulatory risk management of ongoing clinical trials is limited, especially when it involves the safety of the trial. We seek to prospectively evaluate the risk of facing adverse outcomes from standardized and routinely collected protocol data. We conducted a retrospective cohort study of 2860 Phase 2 and Phase 3 trials that were started and completed between 1993 and 2017 and documented in ClinicalTrials.gov. Adverse outcomes considered in our work include Serious or Non-Serious as per the ClinicalTrials.gov definition. Random-forest-based prediction models were created to determine a trial's risk of adverse outcomes based on protocol data that is available before the start of a trial enrollment. A trial's risk is defined by dichotomic (classification) and continuous (log-odds) risk scores. The classification-based prediction models had an area under the curve (AUC) ranging from 0.865 to 0.971 and the continuous-score based models indicate a rank correlation of 0.6-0.66 (with p-values < 0.001), thereby demonstrating improved identification of risk of adverse outcomes. Whereas related frameworks highlight the prediction benefits of incorporating data that is highly context-specific, our results indicate that Adverse Event (AE) risks can be reliably predicted through a framework of mild data requirements. We propose three potential applications in leading regulatory remits, highlighting opportunities to support regulatory oversight and informed consent decisions.

Cardiovascular immunotoxicities associated with immune checkpoint inhibitors: a safety meta-analysis

AIMS 

The risk and incidence of cardiovascular (CV) immune-related adverse events (irAEs) associated with immune checkpoint inhibitors (ICIs) in cancer patients remain unknown.

METHODS AND RESULTS

We systematically reviewed all randomized clinical trials (RCTs) including at least one ICI-containing arm and available CV adverse event (CVAE) data in cancer patients in the ClinicalTrials.gov registry, Medline, and the Cochrane CENTRAL Register of Controlled Trials, up to 31 August 2020 (CRD42020165672). The primary outcome was the summary risk of 16 different CVAEs associated with ICI exposure vs. controls (placebo and non-placebo) in RCTs. CVAEs with an increased risk associated with ICI exposure were considered as CV irAEs. Summary incidences of CV irAEs identified in our primary outcome analyses were computed using all RCTs including at least one ICI-containing arm. We used a random-effects meta-analysis to obtain Peto odds ratios (ORs) with 95% confidence intervals (CIs) and logit transformation and inverse variance weighting to compute summary incidences. Sixty-three unique RCTs with at least one ICI-containing arm (32 518 patients) were retrieved, among which 48 (29 592 patients) had a control arm. Among the 16 CVAEs studied, ICI use was associated with an increased risk of 6 CV irAEs including myocarditis, pericardial diseases, heart failure, dyslipidemia, myocardial infarction, and cerebral arterial ischaemia with higher risks for myocarditis (Peto OR: 4.42, 95% CI: 1.56-12.50, P < 0.01; I2 = 0%, P = 0.93) and dyslipidemia (Peto OR: 3.68, 95% CI: 1.89-7.19, P < 0.01; I2 = 0%, P = 0.66). The incidence of these CVAEs ranged from 3.2 (95% CI 2.0-5.1) to 19.3 (6.7-54.1) per 1000 patients, in studies with a median follow-up ranging from 3.2 to 32.8 months.

CONCLUSION

In RCTs, ICI use was associated with six CV irAEs, not confined to myocarditis and pericarditis.

Pressurized Intraperitoneal Aerosol Chemotherapy-Related Clinical Trials in the Treatment of Peritoneal Metastases

INTRODUCTION

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a treatment option for patients with peritoneal metastases. We evaluated the current status of ongoing prospective clinical trials investigating PIPAC to provide an overview and predict trends in this field.

METHODS

All 367,494 records of clinical trials registered at ClinicalTrials.gov were searched for trials dealing with PIPAC. Active or unpublished trials were further analyzed.

RESULTS

In total, 22 clinical trials were identified and selected for further analyses. Most trials had a single-arm design and were phase I or II. No phase III trials were registered. Academic centers were recorded as primary sponsors in the majority of trials (63.6%). Every year, between 2 and 5 new trials were initiated. In 17 trials (81.8%), PIPAC was used in a palliative setting only, 2 trials performed PIPAC in a neoadjuvant setting, and 2 trials performed PIPAC in an adjuvant setting. Six different drugs (doxorubicin, cisplatin, oxaliplatin, nab-paclitaxel, 5-fluorouracil, and docetaxel) were used in these clinical trials. Most trials investigated the efficacy (n = 15) or safety (n = 7) of PIPAC therapies.

CONCLUSIONS

The results of ongoing clinical trials will bring specific information on indications for PIPAC as well as the impact of PIPAC on quality of life and overall survival.

Selective Reporting of Outcomes in Tinnitus Trials: Comparison of Trial Registries With Corresponding Publications

Objectives: We aimed to study the prevalence of selective reporting of primary and secondary outcomes in tinnitus trials and to examine if selective reporting of outcome measures is influenced by the nature and direction of its results.

Background: Selective reporting of outcome measures has been reported in several biomedical fields and can influence the clinical usefulness and implementation of outcomes of clinical trials. It is reported as one of the obstacles in finding an effective intervention for tinnitus.

Methods: ClinicalTrials.gov (CT.gov) was used to identify all registered interventional tinnitus trials up to December 2015. A standardized search was used to find corresponding publications up to March 2018. The prespecified outcomes in CT.gov were compared with the outcomes reported in corresponding publication(s). The effects of the (lack of) statistical significance of trial results and the effects of funding source on record adherence were evaluated. Changes in registration elements were assessed with the Archive site of CT.gov.

Results: We found corresponding publications for 60 (64.5%) of 93 eligible tinnitus trials registered in CT.gov. Of all the publications, five (7.5%) fully reported outcome measures entirely in line with the prespecified outcome measures. Discrepancies between the prespecified and reported outcomes were found in a total of 51 (76.1%) of the studies for primary outcomes, whereas 62 (92.5%) of the studies had discrepancies in secondary outcomes. In secondary outcomes, statistical significance of trial results influenced CT.gov record adherence. In addition, there was a statistically significant difference in the rate of discrepancy in industry-funded [n = 98 (87.5%) discrepant outcomes] and non-industry funded trials [n = 172 (74.5%) discrepant outcomes] (p = 0.01). Finally, 15 (25.9%) trialists made modifications in registered outcome measures during or after the trial period.

Conclusion: Tinnitus trials suffer from substantial outcome reporting bias. Awareness of its presence must be raised to limit the obstacles of finding an effective intervention for tinnitus.

Delays in reporting and publishing trial results during pandemics: cross sectional analysis of 2009 H1N1, 2014 Ebola, and 2016 Zika clinical trials

BACKGROUND

Pandemic events often trigger a surge of clinical trial activity aimed at rapidly evaluating therapeutic or preventative interventions. Ensuring rapid public access to the complete and unbiased trial record is particularly critical for pandemic research given the urgent associated public health needs. The World Health Organization (WHO) established standards requiring posting of results to a registry within 12 months of trial completion and publication in a peer reviewed journal within 24 months of completion, though compliance with these requirements among pandemic trials is unknown.

METHODS

This cross-sectional analysis characterizes availability of results in trial registries and publications among registered trials performed during the 2009 H1N1 influenza, 2014 Ebola, and 2016 Zika pandemics. We searched trial registries to identify clinical trials testing interventions related to these pandemics, and determined the time elapsed between trial completion and availability of results in the registry. We also performed a comprehensive search of MEDLINE via PubMed, Google Scholar, and EMBASE to identify corresponding peer reviewed publications. The primary outcome was the compliance with either of the WHO's established standards for sharing clinical trial results. Secondary outcomes included compliance with both standards, and assessing the time elapsed between trial completion and public availability of results.

RESULTS

Three hundred thirty-three trials met eligibility criteria, including 261 H1N1 influenza trials, 60 Ebola trials, and 12 Zika trials. Of these, 139 (42%) either had results available in the trial registry within 12 months of study completion or had results available in a peer-reviewed publication within 24 months. Five trials (2%) met both standards. No results were available in either a registry or publication for 59 trials (18%). Among trials with registered results, a median of 42 months (IQR 16-76 months) elapsed between trial completion and results posting. For published trials, the median elapsed time between completion and publication was 21 months (IQR 9-34 months). Results were available within 24 months of study completion in either the trial registry or a peer reviewed publication for 166 trials (50%).

CONCLUSIONS

Very few trials performed during prior pandemic events met established standards for the timely public dissemination of trial results.

Current landscape of type 1 diabetes mellitus-related interventional clinical trials registered on ClinicalTrials.gov: a cross-sectional study

AIMS

A better understanding of the current features of type 1 diabetes mellitus (T1DM)-related interventional clinical trials is important for improving clinical trial designs and identifying neglected research areas. Therefore, this study aimed to comprehensively assess T1DM-related interventional clinical trials registered in the ClinicalTrials.gov database.

METHODS

In this cross-sectional study, T1DM-related clinical trials registered in the ClinicalTrials.gov database were searched on July 1, 2020. The characteristics of the relevant trials were assessed. PubMed and Google Scholar were used to search for publication statuses of primary completed studies.

RESULTS

Overall, 1,421 T1DM-related interventional clinical trials were identified for analysis. Of those trials, 509 (35.8%) involved children and 912 (64.2%) involved only adults. Overall, 63.2% of trials enrolled < 50 participants and 61.9% were registered after patient recruitment. Most trials were single-centered (66.0%). The proportions of trials with children were higher than those with only adults with respect to the primary purpose of health service or prevention (13.6% vs. 4.8%), intervention of device (30.8% vs. 23.9%), education or lifestyle (28.9% vs. 11.3%), and dietary supplement (5.7% vs. 2.5%) (all P < 0.01). Only 24.0% of trials had available results after primary completion. The 5-year cumulative publication rate after primary trial completion was < 40%.

CONCLUSIONS

T1DM-related interventional clinical trials registered in ClinicalTrials.gov were dominated by small single-center studies. Most trials lacked the availability of results and their respective publications. Large multicenter interventional clinical trials on T1DM are needed, and more attention should be paid to improve the publication and dissemination of clinical trials results.

Safety of vaccines used for routine immunization in the United States: An updated systematic review and meta-analysis

BACKGROUND

Understanding the safety of vaccines is critical to inform decisions about vaccination. Our objective was to conduct a systematic review of the safety of vaccines recommended for children, adults, and pregnant women in the United States.

METHODS

We searched the literature in November 2020 to update a 2014 Agency for Healthcare Research and Quality review by integrating newly available data. Studies of vaccines that used a comparator and reported the presence or absence of key adverse events were eligible. Adhering to Evidence-based Practice Center methodology, we assessed the strength of evidence (SoE) for all evidence statements. The systematic review is registered in PROSPERO (CRD42020180089).

RESULTS

Of 56,603 reviewed citations, 338 studies reported in 518 publications met inclusion criteria. For children, SoE was high for no increased risk of autism following measles, mumps, and rubella (MMR) vaccine. SoE was high for increased risk of febrile seizures with MMR. There was no evidence of increased risk of  intussusception with rotavirus vaccine at the latest follow-up (moderate SoE), nor of diabetes (high SoE). There was no evidence of increased risk or insufficient evidence for key adverse events for newer vaccines such as 9-valent human papillomavirus and meningococcal B vaccines. For adults, there was no evidence of increased risk (varied SoE) or insufficient evidence for key adverse events for the new adjuvanted inactivated influenza vaccine and recombinant adjuvanted zoster vaccine. We found no evidence of increased risk (varied SoE) for key adverse events among pregnant women following tetanus, diphtheria, and acellular pertussis vaccine, including stillbirth (moderate SoE).

CONCLUSIONS

Across a large body of research we found few associations of vaccines and serious key adverse events; however, rare events are challenging to study. Any adverse events should be weighed against the protective benefits that vaccines provide.

Learnings From Precision Clinical Trial Matching for Oncology Patients Who Received NGS Testing

PURPOSE

Tumor next-generation sequencing reports typically generate trial recommendations for patients based on their diagnosis and genomic profile. However, these require additional refinement and prescreening, which can add to physician burden. We wanted to use human prescreening efforts to efficiently refine these trial options and also elucidate the high-value parameters that have a major impact on efficient trial matching.

METHODS

Clinical trial recommendations were generated based on diagnosis and biomarker criteria using an informatics platform and were further refined by manual prescreening. The refined results were then compared with the initial trial recommendations and the reasons for false-positive matches were evaluated.

RESULTS

Manual prescreening significantly reduced the number of false positives from the informatics generated trial recommendations, as expected. We found that trial-specific criteria, especially recruiting status for individual trial arms, were a high value parameter and led to the largest number of automated false-positive matches.

CONCLUSION

Reflex clinical trial matching approaches that refine trial recommendations based on the clinical details as well as trial-specific criteria have the potential to help alleviate physician burden for selecting the most appropriate trial for their patient. Investing in publicly available resources that capture the recruiting status of a trial at the cohort or arm level would, therefore, allow us to make meaningful contributions to increase the clinical trial enrollments by eliminating false positives.

Automated Identification of Common Disease-Specific Outcomes for Comparative Effectiveness Research Using ClinicalTrials.gov: Algorithm Development and Validation Study

Background

Common disease-specific outcomes are vital for ensuring comparability of clinical trial data and enabling meta analyses and interstudy comparisons. Traditionally, the process of deciding which outcomes should be recommended as common for a particular disease relied on assembling and surveying panels of subject-matter experts. This is usually a time-consuming and laborious process.

Objective

The objectives of this work were to develop and evaluate a generalized pipeline that can automatically identify common outcomes specific to any given disease by finding, downloading, and analyzing data of previous clinical trials relevant to that disease.

Methods

An automated pipeline to interface with ClinicalTrials.gov’s application programming interface and download the relevant trials for the input condition was designed. The primary and secondary outcomes of those trials were parsed and grouped based on text similarity and ranked based on frequency. The quality and usefulness of the pipeline’s output were assessed by comparing the top outcomes identified by it for chronic obstructive pulmonary disease (COPD) to a list of 80 outcomes manually abstracted from the most frequently cited and comprehensive reviews delineating clinical outcomes for COPD.

Results

The common disease-specific outcome pipeline successfully downloaded and processed 3876 studies related to COPD. Manual verification indicated that the pipeline was downloading and processing the same number of trials as were obtained from the self-service ClinicalTrials.gov portal. Evaluating the automatically identified outcomes against the manually abstracted ones showed that the pipeline achieved a recall of 92% and precision of 79%. The precision number indicated that the pipeline was identifying many outcomes that were not covered in the literature reviews. Assessment of those outcomes indicated that they are relevant to COPD and could be considered in future research.

Conclusions

An automated evidence-based pipeline can identify common clinical trial outcomes of comparable breadth and quality as the outcomes identified in comprehensive literature reviews. Moreover, such an approach can highlight relevant outcomes for further consideration.

Overview of Clinical Trials on Type 2 Diabetes Mellitus: A Comprehensive Analysis of the ClinicalTrials.gov Database

PURPOSE

A better understanding of the current features of type 2 diabetes mellitus (T2DM)-related clinical trials is important for improving designs of clinical trials and identifying neglected areas of research. It was hypothesized that the trial registration policy promoted the designs of T2DM-related trials over the years. Therefore, this study aimed to present a comprehensive overview of T2DM-related clinical trials registered in the ClinicalTrials.gov database.

METHODS

T2DM-related clinical trials registered in the ClinicalTrials.gov database were searched and assessed the characteristics of the relevant trials. We searched PubMed and Google Scholar for the publication statuses of the primary completed trials.

RESULTS

Overall, 5117 T2DM-related trials were identified for analysis. Of the interventional trials, 71.5% had a primary treatment purpose while only 8.9% were prevention or health service. There were more interventional trials registered prior to patient recruitment between 2012 and 2019 than between 2004 and 2011 (44.6% vs 19.9%, P<0.001). The period between 2012 and 2019 also had more trials that enrolled <100 participants (59.2% vs 50.9%), were single-center studies (60.7% vs 50.6%), had non-randomized allocations (11.3% vs 6.3%), were open-label (49.2% vs 45.6%), and had smaller sample sizes than the period between 2004 and 2011 (all P<0.001). The five-year cumulative publication rates after primary completion of the trials were <40%.

CONCLUSION

Although the ClinicalTrials.gov database did not include all clinical trials, the trials registered in the ClinicalTrials.gov database still accounted for most of the clinical studies. Encouragingly, more interventional trials were registered prior to patient recruitment over the years. The majority of T2DM-related clinical trials focused on drug-related treatment, and trials regarding prevention in T2DM should be promoted. More attention should be paid to improve the publication and dissemination of clinical trials results.

Missing clinical trial data: the evidence gap in primary data for potential COVID-19 drugs

BACKGROUND

Several drugs are being repurposed for the treatment of the coronavirus disease 2019 (COVID-19) pandemic based on in vitro or early clinical findings. As these drugs are being used in varied regimens and dosages, it is important to enable synthesis of existing safety data from clinical trials. However, availability of safety information is limited by a lack of timely reporting of overall clinical trial results on public registries or through academic publication. We aimed to analyse the evidence gap in this data by conducting a rapid review of results posting on ClinicalTrials.gov and in academic publications to quantify the number of trials missing results for drugs potentially being repurposed for COVID-19.

METHODS

ClinicalTrials.gov was searched for 19 drugs that have been identified as potential treatments for COVID-19. Relevant clinical trials for any prior indication were listed by identifier (NCT number) and checked for results and for timely result reporting (within 395 days of the primary completion date). Additionally, PubMed and Google Scholar were searched to identify publications of results not listed on the registry. A second, blinded search of 10% of trials was conducted to assess reviewer concordance.

RESULTS

Of 3754 completed trials, 1516 (40.4%) did not post results on ClinicalTrials.gov or in the academic literature. Tabular results were available on ClinicalTrials.gov for 1172 (31.2%) completed trials. A further 1066 (28.4%) had published results in the academic literature, but did not report results on ClinicalTrials.gov . Key drugs missing clinical trial results include hydroxychloroquine (37.0% completed trials unreported), favipiravir (77.8%) and lopinavir (40.5%).

CONCLUSIONS

There is an important evidence gap for the safety of drugs being repurposed for COVID-19. This uncertainty could cause unnecessary additional morbidity and mortality during the pandemic. We recommend caution in experimental drug use for non-severe disease and urge clinical trial sponsors to report missing results retrospectively.

Myelodysplastic syndrome and acute myeloid leukaemia in patients treated with PARP inhibitors: a safety meta-analysis of randomised controlled trials and a retrospective study of the WHO pharmacovigilance database

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors have shown efficacy and acceptable safety in a range of neoplasms, particularly in ovarian cancers. However, some concerns have emerged regarding rare and delayed adverse events including cases of myelodysplastic syndrome and acute myeloid leukaemia, for which data are scarce. The aim of this study was to estimate the risk of myelodysplastic syndrome and acute myeloid leukaemia related to PARP inhibitors, via a systematic review and safety meta-analysis, and to describe clinical features of PARP inhibitor-related myelodysplastic syndrome and acute myeloid leukaemia cases reported in WHO's pharmacovigilance database (VigiBase).

METHODS

We systematically reviewed randomised controlled trials (RCTs) comparing PARP inhibitor therapy versus control treatments (placebo and non-placebo) in adults (age ≥18 years) treated for cancer in MEDLINE, the Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov registry with ongoing surveillance up to May 31, 2020. The date range for included studies was not restricted. By a stepwise method to capture all available adverse events, we first extracted data on myelodysplastic syndrome and acute myeloid leukaemia cases from ClinicalTrials.gov. If cases were not available, we extracted them from published manuscripts, or subsequently contacted corresponding authors or sponsors to provide data. RCTs without available data from ClinicalTrials.gov, publications, or corresponding authors or sponsors were excluded. The primary outcome was the summary risk of myelodysplastic syndrome and acute myeloid leukaemia related to PARP inhibition versus placebo treatment in RCTs. We used a fixed-effects meta-analysis to obtain Peto odds ratios (ORs) with 95% CIs. In a separate observational, retrospective, cross-sectional pharmacovigilance study of VigiBase, cases of myelodysplastic syndrome and acute myeloid leukaemia related to PARP inhibitor therapy were extracted on May 3, 2020, and clinical features summarised with a focus on median duration of PARP inhibitor exposure, median latency period between first drug exposure and diagnosis, and proportion of cases resulting in death. Our systematic review and safety meta-analysis were registered with PROSPERO, CRD42020175050. Our retrospective pharmacovigilance study was registered on ClinicalTrials.gov, NCT04326023.

FINDINGS

For our safety meta-analysis, initial searches identified 1617 citations, and 31 RCTs were systematically reviewed for eligibility. 28 RCTs with available adverse events were analysed (18 placebo and ten non-placebo RCTs), with 5693 patients in PARP inhibitor groups and 3406 patients in control groups. Based on the 18 placebo RCTs (n=7307 patients), PARP inhibitors significantly increased the risk of myelodysplastic syndrome and acute myeloid leukaemia compared with placebo treatment (Peto OR 2·63 [95% CI 1·13-6·14], p=0·026) with no between-study heterogeneity (I²=0%, χ² p=0·91). The incidence of myelodysplastic syndrome and acute myeloid leukaemia across PARP inhibitor groups was 0·73% (95% CI 0·50-1·07; I²=0%, χ² p=0·87; 21 events out of 4533 patients) and across placebo groups was 0·47% (0·26-0·85; I²=0%, χ² p=1·00; three events out of 2774 patients). All 28 RCTs were rated as having unclear risk of bias. In VigiBase, 178 cases of myelodysplastic syndrome (n=99) and acute myeloid leukaemia (n=79) related to PARP inhibitor therapy were extracted. In cases with available data, median treatment duration was 9·8 months (IQR 3·6-17·4; n=96) and median latency period since first exposure to a PARP inhibitor was 17·8 months (8·4-29·2; n=58). Of 104 cases that reported outcomes, 47 (45%) resulted in death.

INTERPRETATION

PARP inhibitors increased the risk of myelodysplastic syndrome and acute myeloid leukaemia versus placebo treatment. These delayed and often lethal adverse events should be studied further to improve clinical understanding, particularly in the front-line maintenance setting.

FUNDING

None.

Association between switching of primary outcomes and reported trial findings among randomized drug trials from China

BACKGROUND AND OBJECTIVE

To evaluate the association between the nature of findings and the switching of registered primary outcomes among randomized controlled trials (RCTs) from mainland China.

METHODS

This is a retrospective cohort study. We retrieved RCTs from trial registries and identified the corresponding journal articles from bibliographic databases until August 2019. Trial registries and journal articles were compared to evaluate whether registered primary outcomes with negative findings were more likely to be switched to secondary outcomes in the subsequent journal articles than those with positive findings.

RESULTS

Switching of registered primary outcomes occurred in 131 (45%) of 294 RCTs. A total of 450 registered primary outcomes were matched to 522 (37%) primary outcomes and 871 (63%) secondary outcomes in the journal articles. Among RCTs registered before they started, the odds of switching primary outcomes with negative findings were 2.64 (95% CI: 1.16-6.02) times the odds of switching those with positive findings. Among RCTs registered when they were ongoing, the odds of switching primary outcomes with negative findings were 8.84 (95% CI: 3.62-25.93) times the odds of switching those with positive findings.

CONCLUSION

The nature of findings may play a role in how likely a prespecified primary outcome is switched subsequently.

Assessment of Duplicate Publication of Chinese-Sponsored Randomized Clinical Trials

IMPORTANCE

Duplicate publications of randomized clinical trials are prevalent in the health-related literature. To date, few studies have assessed the interaction between duplicate publication and the language of the original publication.

OBJECTIVE

To assess the existence of duplicate publication and the extent to which duplicate publication is associated with the language of the original publication.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, eligible randomized clinical trials were retrieved from trial registries, and bibliographic databases were searched to determine their publication status. Eligible randomized clinical trials were for drug interventions from January 1, 2008, to December 31, 2014. The search and analysis were conducted from March 1 to August 31, 2019. The trial registries were either primary registries recognized by the World Health Organization or the Drug Clinical Trial Registry Platform sponsored by the China Food and Drug Administration.

EXPOSURES

Individual randomized clinical trials with positive vs negative results.

MAIN OUTCOMES AND MEASURES

Journal articles were classified as main articles (determined by largest sample size and longest follow-up among all journal articles derived from that randomized clinical trial) and duplicates. The duplicates were classified into 4 types: (1) unreferenced subgroup analysis (article did not disclose itself as a subgroup analysis or reference its main article); (2) unreferenced republication (article did not disclose itself as a replicate of the main article or reference it); (3) unreferenced interim analysis (article did not disclose itself as an interim analysis or reference its main article); and (4) partial duplicate (article did not disclose its sharing a subset of participants with other articles or reference them).

RESULTS

Among 470 randomized clinical trials published by August 2019 as journal articles, 55 (11.7%) had 75 duplicates, of which 53 (70.7%) were cross-language duplicates. Of the 75 duplicates, 33 (44.0%) were unreferenced republications, 25 (33.3%) unreferenced subgroup analyses, 15 (20.0%) unreferenced interim analyses, and 2 (2.7%) partial duplicates. When the main article of a randomized clinical trial was published in Chinese, those with positive findings were 2.48 (95% CI, 1.08-5.71) times more likely to have subsequent duplicate publication than those with negative findings.

CONCLUSIONS AND RELEVANCE

In this study, most duplicates were cross-language duplicates and the most common type was unreferenced republication of the main article. Duplicate publication bias exists when the main articles of randomized clinical trials were published in Chinese, potentially misleading readers and compromising journals and evidence synthesis.