Outcome reporting among drug trials registered in ClinicalTrials.gov

The safety of thiazolidinediones

INTRODUCTION

The prevalence of type 2 diabetes mellitus (T2DM) has reached epidemic proportions. Many new therapies have emerged, including thiazolidinediones (TZDs), selective agonists of PPAR-γ, now used as both primary and add-on therapies. Given that T2DM is a lifetime disease, there is a need for assurance that new drugs are both safe and effective. Recent concern about the cardiovascular safety of one of the new drugs, rosiglitazone, is the stimulus for this review.

AREAS COVERED

The safety of pioglitazone and rosiglitazone under the headings of liver safety, cardiovascular safety, fluid retention, weight gain and bone fractures is reviewed based on a PubMed search of the years 1997 through June 2010. This review also describes the magnitude of the risks of the TZDs and provides a recommendation on the use of TZDs.

EXPERT OPINION

Liver safety is no longer an issue with the TZDs. There are no significant differences between rosiglitazone and pioglitazone in fluid retention, weight gain and bone fractures. However, pioglitazone tends to be cardioprotective while rosiglitazone is cardiotoxic. There is no current justification for prescribing rosiglitazone.

Publication bias in reproductive medicine: from the European Society of Human Reproduction and Embryology annual meeting to publication

BACKGROUND

Treatment decisions should ideally be based on well-designed randomized controlled trials (RCTs). Here we determine the rate of full publication of RCTs presented at annual meetings of the European Society of Human Reproduction and Embryology (ESHRE), identify potential bias against publishing non-significant results and results not favoring the experimental arm, quantify this bias in case it exists, and identify factors associated with time to publication.

METHODS

RCTs presented at ESHRE meetings 2003 and 2004 were recorded. Subsequent search in Medline, Cochrane Library and EMBASE was performed through December 2010 to identify full-text publication in a peer-review journal.

RESULTS

Among 155 abstracts describing RCTs 89 (57%) were published in full-text in a peer-review journal. Median time from presentation to publication was 15 months (range: 0-75). In bivariate analysis, only type of presentation and presence of outcomes favoring the experimental arm were related to publication rate. Studies presented orally or reporting a positive outcome in favor of the experimental arm were more likely to be published (P = 0.018 and 0.014, respectively). Results were consistent in a multivariable logistic regression, with odds ratio (OR) 2.51 [95% confidence interval (CI), 1.25-5.03] for oral versus poster presentations and OR 2.46 (95% CI, 1.23-4.95) for trials favoring versus not favoring the experimental arm. Kaplan-Meier curves revealed time to publication was shorter for oral presentations (log-rank test = 0.013) and trials favoring the experimental arm, compared with all others (log rank = 0.007).

CONCLUSIONS

RCTs with significant results in favor of the experimental arm are more likely to be published and are published sooner. Publication bias in reproductive medicine is a fact.

Knowledge of ghostwriting and financial conflicts-of-interest reduces the perceived credibility of biomedical research

BACKGROUND

While the impact of conflicts-of-interest (COI) is of increasing concern in academic medicine, there is little research on the reaction of practicing clinicians to the disclosure of such conflicts. We developed two research vignettes presenting a fictional antidepressant medication study, one in which the principal investigator had no COI and another in which there were multiple COI disclosed. We confirmed the face validity of the COI vignette through consultation with experts. Hospital-based clinicians were randomly assigned to read one of these two vignettes and then administered a credibility scale.

FINDINGS

Perceived credibility ratings were much lower in the COI group, with a difference of 11.00 points (31.42%) on the credibility scale total as calculated through the Mann-Whitney U test (95% CI = 6.99 - 15.00, p < .001). Clinicians in the COI group were also less likely to recommend the antidepressant medication discussed in the vignette (Odds Ratio = 0.163, 95% CI = .03 = 0.875).

CONCLUSIONS

In this study, increased disclosure of COI resulted in lower credibility ratings.

Comparison of protocols and registry entries to published reports for randomised controlled trials

BACKGROUND

Publication of complete trial results is essential if people are to be able to make well-informed decisions about health care. Selective reporting of randomised controlled trials (RCTs) is a common problem.

OBJECTIVES

To systematically review studies of cohorts of RCTs to compare the content of trial reports with the information contained in their protocols, or entries in a trial registry.

SEARCH STRATEGY

We conducted electronic searches in Ovid MEDLINE (1950 to August 2010); Ovid EMBASE (1980 to August 2010); ISI Web of Science (1900 to August 2010) and the Cochrane Methodology Register (Issue 3, 2010), checked reference lists, and asked authors of eligible studies to identify further studies. Studies were not excluded based on language of publication or our assessment of their quality.

SELECTION CRITERIA

Published or unpublished cohort studies comparing the content of protocols or trial registry entries with published trial reports.

DATA COLLECTION AND ANALYSIS

Data were extracted by two authors independently. Risk of bias in the cohort studies was assessed in relation to follow up and selective reporting of outcomes. Results are presented separately for the comparison of published reports to protocols and trial registry entries.

MAIN RESULTS

We included 16 studies assessing a median of 54 RCTs (range: 2 to 362). Twelve studies compared protocols to published reports and four compared trial registry entries to published reports. In two studies, eligibility criteria differed between the protocol and publication in 19% and 100% RCTs. In one study, 16% (9/58) of the reports included the same sample size calculation as the protocol. In one study, 6% (4/63) of protocol-report pairs gave conflicting information regarding the method of allocation concealment, and 67% (49/73) of blinded studies reported discrepant information on who was blinded. In one study unacknowledged discrepancies were found for methods of handling protocol deviations (44%; 19/43), missing data (80%; 39/49), primary outcome analyses (60%; 25/42) and adjusted analyses (82%; 23/28). One study found that of 13 protocols specifying subgroup analyses, 12 of these 13 trials reported only some, or none, of these. Two studies found that statistically significant outcomes had a higher odds of being fully reported compared to nonsignificant outcomes (range of odds ratios: 2.4 to 4.7). Across the studies, at least one primary outcome was changed, introduced, or omitted in 4-50% of trial reports.

AUTHORS' CONCLUSIONS

Discrepancies between protocols or trial registry entries and trial reports were common, although reasons for these were not discussed in the reports. Full transparency will be possible only when protocols are made publicly available or the quality and extent of information included in trial registries is improved, and trialists explain substantial changes in their reports.

Frequency and reasons for outcome reporting bias in clinical trials: interviews with trialists

OBJECTIVES

To provide information on the frequency and reasons for outcome reporting bias in clinical trials.

DESIGN

Trial protocols were compared with subsequent publication(s) to identify any discrepancies in the outcomes reported, and telephone interviews were conducted with the respective trialists to investigate more extensively the reporting of the research and the issue of unreported outcomes.

PARTICIPANTS

Chief investigators, or lead or coauthors of trials, were identified from two sources: trials published since 2002 covered in Cochrane systematic reviews where at least one trial analysed was suspected of being at risk of outcome reporting bias (issue 4, 2006; issue 1, 2007, and issue 2, 2007 of the Cochrane library); and a random sample of trial reports indexed on PubMed between August 2007 and July 2008.

SETTING

Australia, Canada, Germany, the Netherlands, New Zealand, the United Kingdom, and the United States.

MAIN OUTCOME MEASURES

Frequency of incomplete outcome reporting-signified by outcomes that were specified in a trial's protocol but not fully reported in subsequent publications-and trialists' reasons for incomplete reporting of outcomes.

RESULTS

268 trials were identified for inclusion (183 from the cohort of Cochrane systematic reviews and 85 from PubMed). Initially, 161 respective investigators responded to our requests for interview, 130 (81%) of whom agreed to be interviewed. However, failure to achieve subsequent contact, obtain a copy of the study protocol, or both meant that final interviews were conducted with 59 (37%) of the 161 trialists. Sixteen trial investigators failed to report analysed outcomes at the time of the primary publication, 17 trialists collected outcome data that were subsequently not analysed, and five trialists did not measure a prespecified outcome over the course of the trial. In almost all trials in which prespecified outcomes had been analysed but not reported (15/16, 94%), this under-reporting resulted in bias. In nearly a quarter of trials in which prespecified outcomes had been measured but not analysed (4/17, 24%), the "direction" of the main findings influenced the investigators' decision not to analyse the remaining data collected. In 14 (67%) of the 21 randomly selected PubMed trials, there was at least one unreported efficacy or harm outcome. More than a quarter (6/21, 29%) of these trials were found to have displayed outcome reporting bias.

CONCLUSION

The prevalence of incomplete outcome reporting is high. Trialists seemed generally unaware of the implications for the evidence base of not reporting all outcomes and protocol changes. A general lack of consensus regarding the choice of outcomes in particular clinical settings was evident and affects trial design, conduct, analysis, and reporting.

Characteristics of randomised trials on diseases in the digestive system registered in ClinicalTrials.gov: a retrospective analysis

Objectives To evaluate the adequacy of reporting of protocols for randomised trials on diseases of the digestive system registered in http://ClinicalTrials.gov and the consistency between primary outcomes, secondary outcomes and sample size specified in http://ClinicalTrials.gov and published trials. Methods Randomised phase III trials on adult patients with gastrointestinal diseases registered before January 2009 in http://ClinicalTrials.gov were eligible for inclusion. From http://ClinicalTrials.gov all data elements in the database required by the International Committee of Medical Journal Editors (ICMJE) member journals were extracted. The subsequent publications for registered trials were identified. For published trials, data concerning publication date, primary and secondary endpoint, sample size, and whether the journal adhered to ICMJE principles were extracted. Differences between primary and secondary outcomes, sample size and sample size calculations data in http://ClinicalTrials.gov and in the published paper were registered. Results 105 trials were evaluated. 66 trials (63%) were published. 30% of trials were registered incorrectly after their completion date. Several data elements of the required ICMJE data list were not filled in, with missing data in 22% and 11%, respectively, of cases concerning the primary outcome measure and sample size. In 26% of the published papers, data on sample size calculations were missing and discrepancies between sample size reporting in http://ClinicalTrials.gov and published trials existed. Conclusion The quality of registration of randomised controlled trials still needs improvement.

Improving academic leadership and oversight in large industry-sponsored clinical trials: the ARO-CRO model

Standards for clinical trial design, execution, and publication have increased in recent years. However, the current structure for interaction among the pharmaceutical sponsor funding a drug or device development program, the contract research organization (CRO) that typically assists in executing the trial, regulatory agencies, and academicians, provides inadequate leadership and oversight of the development process. Conventional academic steering committees are not provided with the independent infrastructure by which to verify statistical analyses and conclusions regarding safety and efficacy. We propose an alternative approach centered on partnerships between CROs and university-based academic research organizations (AROs). In this model, the ARO takes responsibility for processes that address journal requirements and regulatory expectations for independent academic oversight (including oversight of Steering Committee and Data and Safety Monitoring Board activities), whereas the CRO provides infrastructure for efficient trial execution, site monitoring, and data management. The ARO engages academic experts throughout the trial process and minimizes conflicts of interest in individual industry relationships via diversification of sponsors, agents, and therapeutic areas. Although numerous models can be entertained, the ARO-CRO model is uniquely structured to meet the demand for greater assurance of integrity in clinical trials and the needs of each stakeholder in the process.