Compliance with trial registration in five core journals of clinical geriatrics: a survey of original publications on randomised controlled trials from 2008 to 2012

Impact of COVID-19 on utilization of maternal and child health services in India: Health management information system data analysis

Background/Objectives

Studies globally have documented the impact of COVID 19 on maternal and newborn health services. This study assesses the impact of COVID-19 on essential maternal and child health (MCH) services in India based on the national Health Management Information System (HMIS).

Methods

Present retrospective study used secondary data analysis upon the routinely collected data accessed from Health Management Information System. Microdata on maternal and newborn indicators was extracted for all states between April and June during 2019, 2020 and 2021. Relative change for each indicator were taken into consideration for the year 2020 and 2021; with respect to the outcomes in 2019.

Results

Compared to 2019, antenatal care registrations saw a decline in all states for both periods in 2020 and 2021 except for Sikkim, Telangana, Maharashtra and Andhra Pradesh. Similarly, the relative changes in 2019 pertaining to the proportion of pregnant women provided with emergency obstetric care for pregnancy complications registered a decline in all states except for Himachal Pradesh, Telangana and Arunachal Pradesh. There was a decreasing trend noted in institutional deliveries in 2020 and 2021 among all major states. However, an increasing trend was seen in the number of immunization sessions held among all major states.

Conclusion

The study demonstrates a disruption in service delivery during the lockdown period in the first wave and the peak of the second wave. Further qualitative studies need to be undertaken to generate evidence for maintaining continuum of care during a pandemic situation.

Reporting of retrospective registration in clinical trial publications: a cross-sectional study of German trials

OBJECTIVE

Prospective registration has been widely implemented and accepted as a best practice in clinical research, but retrospective registration is still commonly found. We assessed to what extent retrospective registration is reported transparently in journal publications and investigated factors associated with transparent reporting.

DESIGN

We used a dataset of trials registered in ClinicalTrials.gov or Deutsches Register Klinischer Studien, with a German University Medical Center as the lead centre, completed in 2009-2017, and with a corresponding peer-reviewed results publication. We extracted all registration statements from results publications of retrospectively registered trials and assessed whether they mention or justify the retrospective registration. We analysed associations of retrospective registration and reporting thereof with registration number reporting, International Committee of Medical Journal Editors (ICMJE) membership/-following and industry sponsorship using χ² or Fisher exact test.

RESULTS

In the dataset of 1927 trials with a corresponding results publication, 956 (53.7%) were retrospectively registered. Of those, 2.2% (21) explicitly report the retrospective registration in the abstract and 3.5% (33) in the full text. In 2.1% (20) of publications, authors provide an explanation for the retrospective registration in the full text. Registration numbers were significantly underreported in abstracts of retrospectively registered trials compared with prospectively registered trials. Publications in ICMJE member journals did not have statistically significantly higher rates of both prospective registration and disclosure of retrospective registration, and publications in journals claiming to follow ICMJE recommendations showed statistically significantly lower rates compared with non-ICMJE-following journals. Industry sponsorship of trials was significantly associated with higher rates of prospective registration, but not with transparent registration reporting.

CONCLUSIONS

Contrary to ICMJE guidance, retrospective registration is disclosed and explained only in a small number of retrospectively registered studies. Disclosure of the retrospective nature of the registration would require a brief statement in the manuscript and could be easily implemented by journals.

A comparison of registered and published primary outcomes in clinical trials of opioid use disorder: ACTTION review and recommendations

BACKGROUND AND AIMS

Prospective trial registration can increase research integrity. This Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) review was designed to compare the primary outcomes (PO) reported in registries with associated publications for opioid use disorder (OUD) clinical trials.

DESIGN

The World Health Organization's International Clinical Trials Registry Platform (ICTRP) was searched for completed trials (2010 through 2019). Associated publications were identified and paired with trial registry data based on the publication date.

MEASUREMENTS

Reviewers independently rated the occurrence of discrepancies between the POs in the registry compared to the publication. An analysis of prospective versus retrospective registration was also completed.

FINDINGS

One-hundred and forty trials were identified in the search, and 43 registry-publication pairs evaluated. Only 34 of the 43 pairs could be examined for discrepancies because nine did not report a PO in registry and publication. Of the 34 pairs, only four met rigorous criteria for prospective trial registration and had an exact match of POs. In contrast, the majority of the 34 trials, or 80%, had inconsistent POs (e.g., registered secondary outcomes published as primary; the timing of PO not specified) and/or were retrospectively registered.

CONCLUSIONS

Many clinical trials focused on OUD have not met the standards of trial registration, such as consistent reporting of POs and prospective registration. Failure to properly register trial characteristics undermines the validity of research findings and can delay the development of life-saving treatments. Recommendations for improving prospective trial reporting practices are provided.

Clinical Trials Registry - India: A decadal perspective

OBJECTIVE:

To present a descriptive analysis of the clinical studies registered in the Clinical Trials Registry – India (CTRI) and deduce its impact.

METHODS:

We searched the CTRI database for all registered clinical studies from July 20, 2007 to May 31, 2018. Extracted data were analyzed in three time periods i.e., Periods 1, 2, and 3 based on the major activities and milestones of the CTRI. In addition, comparative registrations of the various Primary Registries of the WHO were compiled and registration policy of Indian journals with regard to trial registration assessed.

RESULTS:

A total of 20,160 clinical studies were submitted to the CTRI in the designated study period. Of the registered 14,341 clinical studies, 10,485 (76.3%) were interventional trials which were either regulatory (n = 2004), academic non-regulatory (n = 3855), or those conducted as part of PG thesis (n = 4626) trials. Regulatory trials registration numbers varied according to the Indian regulatory scenario. PG thesis trial registrations showed a steep rise, although unlike regulatory trials, these were mostly retrospective registrations. CTRI registration numbers were comparable to that in other Primary Registries. Instructions to authors of 48% indexed Indian journals made a mention of trial registration.

CONCLUSIONS:

The CTRI has a strong global presence and has enhanced the transparency of regulatory trials as well as academic research particularly thesis-based work. The latter is expected to help improve standard of research and prevent repetitive research. Additional support from Indian journal editors by strict implementation of prospective registration is crucial for increasing compliance by researchers.

Prospective registration and reporting of trial number in randomised clinical trials: global cross sectional study of the adoption of ICMJE and Declaration of Helsinki recommendations

OBJECTIVES

To evaluate the compliance with prospective registration and inclusion of the trial registration number (TRN) in published randomised controlled trials (RCTs), and to analyse the rationale behind, and detect selective registration bias in, retrospective trial registration.

DESIGN

Cross sectional analysis.

DATA SOURCES

PubMed, the 17 World Health Organization's trial registries, University of Toronto library, International Committee of Medical Journal Editors (ICMJE) list of member journals, and the InCites Journal Citation Reports.

STUDY SELECTION CRITERIA

RCTs registered in any WHO trial registry and published in any PubMed indexed journal in 2018.

RESULTS

This study included 10 500 manuscripts published in 2105 journals. Overall, 71.2% (7473/10500) reported the TRN and 41.7% (3013/7218) complied with prospective trial registration. The univariable and multivariable analyses reported significant relations (P<0.05) between reporting the TRN and the impact factor and ICMJE membership of the publishing journal. A significant relation (P<0.05) was also observed between prospective trial registration and the registry, region, condition, funding, trial size, interval between paper registration and submission dates, impact factor, and ICMJE membership of the publishing journal. A manuscript published in an ICMJE member journal was 5.8 times more likely to include the TRN (odds ratio 5.8, 95% confidence interval 4.0 to 8.2), and a published trial was 1.8 times more likely to be registered prospectively (1.8, 1.5 to 2.2) when published in an ICMJE member journal compared with other journals. This study detected a new form of bias, selective registration bias, with a higher proportion (85.2% (616/723)) of trials registered retrospectively within a year of submission for publication. Higher rates of retrospective registrations were observed within the first three to eight weeks after enrolment of study participants. Within the 286 RCTs registered retrospectively and published in an ICMJE member journal, only 2.8% (8/286) of the authors included a statement justifying the delayed registration. Reasons included lack of awareness, error of omission, and the registration process taking longer than anticipated.

CONCLUSIONS

This study found a high compliance in reporting of the TRN for trial papers published in ICMJE member journals, but prospective trial registration was low.

Discrepancies between Registered and Published Primary and Secondary Outcomes in Randomized Controlled Trials within the Plastic Surgery Literature: A Systematic Review

BACKGROUND

Recent studies have identified a high incidence of discrepancy between registered and published outcomes in registered medical and surgical randomized controlled trials. This has not yet been studied in the plastic surgery literature.

METHODS

The authors systematically assessed plastic surgery randomized controlled trials published between 2012 and 2016 in seven high-impact plastic surgery journals. Data were collected from the registration website and published articles using a standardized data extraction form.

RESULTS

A total of 145 randomized controlled trials were identified, with a 39 percent trial registration rate (n = 57). Forty-nine trials were included in the final analysis. Forty-three (88 percent) had a discrepancy between registered and published outcomes: 26 (53 percent) for primary outcome(s), and 39 (80 percent) for secondary outcome(s). The number of discrepancies in an individual trial ranged from one to seven for primary outcomes and one to 12 for secondary outcomes. Aesthetic surgery had the largest number of trials with outcome discrepancies (n = 15). The prevalence of unreported registered outcomes was 13 percent for primary outcomes and 38 percent for secondary outcomes. Registered nonsignificant primary outcomes were published as nonsignificant secondary outcomes in 30 percent of trials. Publishing new nonregistered secondary outcomes (65 percent) and changing the assessment timing of published primary outcomes (61 percent) were the most common types of discrepancies. Discrepancies favored a statistically significant positive outcome in 19 (44 percent) of the 43 trials with an outcome discrepancy. Discrepancies that resulted in published outcomes with improved patient relevance were found in eight trials (16 percent) for primary outcome discrepancies and 14 trials (29 percent) for secondary outcome discrepancies.

CONCLUSIONS

The plastic surgery literature has high rates of discrepancies between registered and published trial outcomes. Outcome reporting discrepancy is even more problematic for secondary outcomes, an area of analysis that has previously been poorly studied. The high rate of discrepancy change favoring a statistically significant outcome and more patient-relevant outcomes may indicate the pressure to demonstrate significant results to be accepted for publication in high-impact journals.

Selective reporting bias in randomised controlled trials from two network meta-analyses: comparison of clinical trial registrations and their respective publications

OBJECTIVE

To determine (i) the difference in the frequency of serious adverse events (SAEs) reported in trial registrations and their respective primary publications and (ii) the effect of adding SAE data from registries to a network meta-analysis (NMA) in changing the surface under the cumulative ranking (SUCRA) curve values of interventions.

DESIGN

Secondary analysis of primary publications from two NMAs.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included randomised trials published in English after 2005 that were included in two NMAs of pharmacological interventions for Alzheimer's disease and chronic obstructive pulmonary disease.

DATA EXTRACTION

Two reviewers independently searched multiple international trial registries for registration status and abstracted data from the included study publications and ClinicalTrials.gov.

RESULTS

Of the 203 randomised trials included, 140 (69.0%) were registered with a trial registry and 72 (35.5%) posted results in the registry. The proportion of registered trials increased over time (38.5% in 2005 vs 78.6% in 2014). Of the publications with results posted in a trial registry, 14 (19.4%) had inconsistent reporting of overall SAEs; 7 (10.4%) studies did not report SAEs in the publication but did in the registry. In the 134 randomised trials with a prespecified primary outcome in the registry, 19 studies (9.4%) had a change in the primary outcome in the publication. Adding SAEs reported in registries to the NMAs did not affect the ranking of interventions.

CONCLUSION

We identified inconsistent reporting of SAEs in randomised trials that were included in two NMAs. Findings highlight the importance of including trial registries in the grey literature search and verifying safety data before incorporating it into NMAs.

STUDY REGISTRATION

osf.io/mk6dr.

Requirements for trial registration and adherence to reporting guidelines in critical care journals: a meta-epidemiological study of journals' instructions for authors

BACKGROUND

The purpose of this study was to investigate the policies of critical care journals with regard to guideline adoption and clinical trial registration to understand the extent to which journals use these mechanisms to improve reporting practices.

METHODS

The current study's sample comprised 37 critical care journals cataloged in the Expanded Science Citation Index of the 2015 Journal Citation Reports and Google Scholar Metrics h5-index critical care subcategory. A web-based data abstraction was performed to identify which journals required, recommended, or made no mention of 17 different reporting guidelines. We also extracted whether journals required or recommended trial registration. Authors were blinded to one another's ratings until completion of the data validation. Cross tabulations and descriptive statistics were calculated by using STATA 13.

RESULTS

Of the 37 critical care journals, 15 (15/37, 40.5%) did not mention a single guideline within their instructions for authors, whereas the remaining 22 (22/37, 59.5%) mentioned one or more guidelines. The Quality of Reporting of Meta-analyses statement and Standards for Reporting Qualitative Research were not mentioned by any journals, whereas the International Committee of Medical Journal Editors Uniform Requirements for Manuscripts (26/37, 70.3%) and Consolidated Standards of Reporting Trials statement (17/37, 45.9%) were mentioned most often. Of the 37 critical care journals, 21 (21/37, 56.8%) did not mention trial or review registration, but the remaining 16 (16/37, 43.2%) mentioned at least one of the two. Trial registration through ClinicalTrials.gov was mentioned by six (6/37, 16.2%) journals, whereas the WHO registry was mentioned by five (5/37, 13.5%). Sixteen (16/37, 43.2%) journals mentioned trial registration through a registry platform.

CONCLUSION

Nearly half of the journals in our sample did not mention a reporting guideline, and only a small percentage of journals required the registration of clinical trials as a condition for publication. Implementing these two mechanisms may limit bias, and their adoption should be considered by journal editors in critical care.

TRIAL REGISTRATION

UMIN000024081.

Registration, results reporting, and publication bias of clinical trials supporting FDA approval of neuropsychiatric drugs before and after FDAAA: a retrospective cohort study

Background

Mandatory trial registration, and later results reporting, were proposed to mitigate selective clinical trial publication and outcome reporting. The Food and Drug Administration (FDA) Amendments Act (FDAAA) was enacted by Congress on September 27, 2007, requiring the registration of all non-phase I clinical trials involving FDA-regulated medical interventions and results reporting for approved drugs. The association between FDAAA enactment and the registration, results reporting, and publication bias of neuropsychiatric trials has not been studied.

Methods

We conducted a retrospective cohort study of all efficacy trials supporting FDA new drug approvals between 2005 to 2014 for neuropsychiatric indications. Trials were categorized as pre- or post-FDAAA based on initiation and/or completion dates. The main outcomes were the proportions of trials registered and reporting results in ClinicalTrials.gov, and the degree of publication bias, estimated using the relative risks pre- and post-FDAAA of both the publication of positive vs non-positive trials, as well as of publication of positive vs non-positive trials without misleading interpretations. Registration and results reporting proportions were compared pre- and post-FDAAA using the two-tailed Fisher exact test, and the degrees of publication bias were compared by calculating the ratio of relative risks (RRR) for each period.

Results

The FDA approved 37 new drugs for neuropsychiatric indications between 2005 and 2014 on the basis of 142 efficacy trials, of which 101 were pre-FDAAA and 41 post-FDAAA. Post-FDAAA trials were significantly more likely to be registered (100% vs 64%; p < 0.001) and report results (100% vs 10%; p < 0.001) than pre-FDAAA trials. Pre-FDAAA, positive trials were more likely to be published (relative risk [RR] = 1.52; 95% confidence interval [CI] = 1.17–1.99; p = 0.002) and published without misleading interpretations (RR = 2.47; CI = 1.57–3.73; p < 0.001) than those with non-positive results. In contrast, post-FDAAA positive trials were equally likely to have been published (RR = 1; CI = 1–1, p = NA) and published without misleading interpretations (RR = 1.20; CI = 0.84–1.72; p = 0.30). The likelihood of publication bias pre-FDAAA vs post-FDAAA was greater for positive vs non-positive trials (RRR = 1.52; CI = 1.16–1.99; p = 0.002) and for publication without misleading interpretations (RRR = 2.06, CI = 1.17–3.61, p = 0.01).

Conclusions

The enactment of FDAAA was followed by significantly higher proportions of trials that were registered and reporting results on ClinicalTrials.gov and significantly lower degrees of publication bias among trials supporting recent FDA approval of drugs for neuropsychiatric indications.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2957-0) contains supplementary material, which is available to authorized users.

Registration of published randomized trials: a systematic review and meta-analysis

BACKGROUND

Prospective trial registration is a powerful tool to prevent reporting bias. We aimed to determine the extent to which published randomized controlled trials (RCTs) were registered and registered prospectively.

METHODS

We searched MEDLINE and EMBASE from January 2005 to October 2017; we also screened all articles cited by or citing included and excluded studies, and the reference lists of related reviews. We included studies that examined published RCTs and evaluated their registration status, regardless of medical specialty or language. We excluded studies that assessed RCT registration status only through mention of registration in the published RCT, without searching registries or contacting the trial investigators. Two independent reviewers blinded to the other's work performed the selection. Following PRISMA guidelines, two investigators independently extracted data, with discrepancies resolved by consensus. We calculated pooled proportions and 95% confidence intervals using random-effects models.

RESULTS

We analyzed 40 studies examining 8773 RCTs across a wide range of clinical specialties. The pooled proportion of registered RCTs was 53% (95% confidence interval 44% to 58%), with considerable between-study heterogeneity. A subset of 24 studies reported data on prospective registration across 5529 RCTs. The pooled proportion of prospectively registered RCTs was 20% (95% confidence interval 15% to 25%). Subgroup analyses showed that registration was higher for industry-supported and larger RCTs. A meta-regression analysis across 19 studies (5144 RCTs) showed that the proportion of registered trials significantly increased over time, with a mean proportion increase of 27%, from 25 to 52%, between 2005 and 2015.

CONCLUSIONS

The prevalence of trial registration has increased over time, but only one in five published RCTs is prospectively registered, undermining the validity and integrity of biomedical research.

Adherence to the International Committee of Medical Journal Editors' (ICMJE) prospective registration policy and implications for outcome integrity: a cross-sectional analysis of trials published in high-impact specialty society journals

BACKGROUND

Registration of clinical trials is critical for promoting transparency and integrity in medical research; however, trials must be registered in a prospective fashion to deter unaccounted protocol modifications or selection of alternate outcomes that may enhance favorability of reported findings. We assessed adherence to the International Committee of Medical Journal Editors' (ICMJE) prospective registration policy and identified the frequency of registrations occurring after potential observation of primary outcome data among trials published in the highest-impact journals associated with US professional medical societies. Additionally, we examined whether trials that are unregistered or registered after potential observation of primary outcome data were more likely to report favorable findings.

METHODS

We conducted a retrospective, cross-sectional analysis of the 50 most recently published clinical trials that reported primary results in each of the ten highest-impact US medical specialty society journals between 1 January 2010 and 31 December 2015. We used descriptive statistics to characterize the proportions of trials that were: registered; registered retrospectively; registered retrospectively potentially after initial ascertainment of primary outcomes; and reporting favorable findings, overall and stratified by journal and trial characteristics. Chi-squared analyses were performed to assess differences in registration by journal and trial characteristics.

RESULTS

We reviewed 6869 original research reports published between 1 January 2010 and 31 December 2015 to identify a total of 486 trials across 472 publications. Of these 486 trials, 47 (10%) were unregistered. Among 439 registered trials, 340 (77%) were registered prospectively and 99 (23%) retrospectively. Sixty-seven (68%) of these 99 retrospectively registered trials, or 15% of all 439 registered trials, were registered after potential observation of primary outcome data ascertained among participants enrolled at inception. Industry-funded trials, those with enrollment sites in the US, as well as those assessing FDA-regulated interventions each had lower rates of retrospective registration. Unregistered trials were more likely to report favorable findings than were registered trials (89% vs. 64%; relative risk (RR) = 1.38, 95% confidence interval (CI) = 1.20-1.58; p = 0.004), irrespective of registration timing.

CONCLUSIONS

Adherence to the ICMJE's prospective registration policy remains sub-standard, even in the highest-impact journals associated with US professional medical societies. These journals frequently published unregistered trials and trials registered after potential observation of primary outcome data.

A systematic review of the processes used to link clinical trial registrations to their published results

BACKGROUND

Studies measuring the completeness and consistency of trial registration and reporting rely on linking registries with bibliographic databases. In this systematic review, we quantified the processes used to identify these links.

METHODS

PubMed and Embase databases were searched from inception to May 2016 for studies linking trial registries with bibliographic databases. The processes used to establish these links were categorised as automatic when the registration identifier was available in the bibliographic database or publication, or manual when linkage required inference or contacting of trial investigators. The number of links identified by each process was extracted where available. Linear regression was used to determine whether the proportions of links available via automatic processes had increased over time.

RESULTS

In 43 studies that examined cohorts of registry entries, 24 used automatic and manual processes to find articles; 3 only automatic; and 11 only manual (5 did not specify). Twelve studies reported results for both manual and automatic processes and showed that a median of 23% (range from 13 to 42%) included automatic links to articles, while 17% (range from 5 to 42%) of registry entries required manual processes to find articles. There was no evidence that the proportion of registry entries with automatic links had increased (R ² = 0.02, p = 0.36). In 39 studies that examined cohorts of articles, 21 used automatic and manual processes; 9 only automatic; and 2 only manual (7 did not specify). Sixteen studies reported numbers for automatic and manual processes and indicated that a median of 49% (range from 8 to 97%) of articles had automatic links to registry entries, and 10% (range from 0 to 28%) required manual processes to find registry entries. There was no evidence that the proportion of articles with automatic links to registry entries had increased (R ² = 0.01, p = 0.73).

CONCLUSIONS

The linkage of trial registries to their corresponding publications continues to require extensive manual processes. We did not find that the use of automatic linkage has increased over time. Further investigation is needed to inform approaches that will ensure publications are properly linked to trial registrations, thus enabling efficient monitoring of trial reporting.

Do emergency medicine journals promote trial registration and adherence to reporting guidelines? A survey of "Instructions for Authors"

Background

The aim of this study was to evaluate the current state of two publication practices, reporting guidelines requirements and clinical trial registration requirements, by analyzing the “Instructions for Authors” of emergency medicine journals.

Methods

We performed a web-based data abstraction from the “Instructions for Authors” of the 27 Emergency Medicine journals catalogued in the Expanded Science Citation Index of the 2014 Journal Citation Reports and Google Scholar Metrics h5-index to identify whether each journal required, recommended, or made no mention of the following reporting guidelines: EQUATOR Network, ICMJE, ARRIVE, CARE, CONSORT, STARD, TRIPOD, CHEERS, MOOSE, STROBE, COREQ, SRQR, SQUIRE, PRISMA-P, SPIRIT, PRISMA, and QUOROM. We also extracted whether journals required or recommended trial registration. Authors were blinded to one another’s ratings until completion of the data validation. Cross-tabulations and descriptive statistics were calculated using IBM SPSS 22.

Results

Of the 27 emergency medicine journals, 11 (11/27, 40.7%) did not mention a single guideline within their “Instructions for Authors,” while the remaining 16 (16/27, 59.3%) mentioned one or more guidelines. The QUOROM statement and SRQR were not mentioned by any journals whereas the ICMJE guidelines (18/27, 66.7%) and CONSORT statement (15/27, 55.6%) were mentioned most often. Of the 27 emergency medicine journals, 15 (15/27, 55.6%) did not mention trial or review registration, while the remaining 12 (12/27, 44.4%) at least mentioned one of the two. Trial registration through ClinicalTrials.gov was mentioned by seven (7/27, 25.9%) journals while the WHO registry was mentioned by four (4/27, 14.8%). Twelve (12/27, 44.4%) journals mentioned trial registration through any registry platform.

Discussion

The aim of this study was to evaluate the current state of two publication practices, reporting guidelines requirements and clinical trial registration requirements, by analyzing the “Instructions for Authors” of emergency medicine journals. In this study, there was not a single reporting guideline mentioned in more than half of the journals. This undermines efforts of other journals to improve the completeness and transparency of research reporting.

Conclusions

Reporting guidelines are infrequently required or recommended by emergency medicine journals. Furthermore, few require clinical trial registration. These two mechanisms may limit bias and should be considered for adoption by journal editors in emergency medicine.

Trial registration

UMIN000022486

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-016-0331-3) contains supplementary material, which is available to authorized users.

Prevention of selective outcome reporting: let us start from the beginning

BACKGROUND

Healthcare professionals and patients could be negatively influenced in their judgments by articles and meta-analyses presenting selective outcome reporting. Clinical trials should be transparent from inception to the publication of results. To this end, trial prospective registration is an ethical and scientific requirement that have shown to be effective in preventing selective reporting of outcomes. However, even journals with a clear pre-registration policy publish trial results that were retrospectively registered.

SITUATION

Analyses of registration of randomized clinical trials recently published in top specialty journals and of meta-analyses with suspicion of including trials with outcome reporting bias have shown that retrospective registration is in the range from 56 to 76 %. This translates into publication of primary endpoints that differ from those included in the registry: some 30 % of trials showed discrepancies between the primary endpoint in the trial registry and the article. Furthermore, it has been shown that 8 % of all clinical trials published by 6 high-impact ICMJE-member journals was retrospectively registered after primary endpoint ascertainment could have had taken place, raising concerns that endpoints may not have been pre-specified, or were changed. With regards to meta-analyses, 34 % of Cochrane systematic reviews included one or more trials with a high suspicion of selective reporting bias for the primary outcome.

PROPOSAL

Retrospective registration of trials may foster selective outcome reporting unless journal editors implement specific quality control processes aiming to prevent or minimize this type of bias. Prospective registration of trials-and protocol public disclosure if proven effective in future studies-prevents outcome reporting bias, a must to ensure clinicians and patients have access to reliable clinical trial results. Journal editors should enforce, rather than encourage, appropriate measures to ensure publication of trials free of outcome reporting bias.