Trial registration records, updates, and protocols

Assessment of frequency and reporting of design changes among clinical drug trials published in influential medical journals

BACKGROUND

Modifications of primary outcome measures after trial initiation can undermine their scientific validity. We aimed to quantify these changes and to characterize potential predictors in clinical drug trials published in high impact factor general medicine journals.

METHODS

The study cohort included all prospective, adult drug clinical trials published in the New England Journal of Medicine, JAMA and Lancet between June 2017 and May 2018. The matching ClinicalTrials.gov entries effective at trial initiation were compared with those effective on July 2018, thereby identifying amendments to primary outcome definitions and assessment timeframes and the planned sample size (defined as >10% change). The primary publications were reviewed for reporting of these amendments. Associations between identified changes and trial characteristics were explored using logistic regression.

RESULTS

Of the 147 included trials, modifications to primary outcome measures were identified in 80 (54%). Primary outcome definitions, outcome assessment timeframes and the planned sample size were modified in 28 (19%), 12 (8%) and 65 (45%) of registry entries, respectively; of which 21 (75%), 11 (92%), and 33 (51%), respectively, were not reported in the related publications. There were no significant associations between modifications in registry entries and study characteristics.

CONCLUSIONS

Approximately half of trials published in influential medical journals present changes to the design while patient accrual is ongoing, and two thirds of them are unreported. Justification for such modifications should be reported more clearly. Reviewers, editors and readers should consult ClinicalTrials.gov for a more comprehensive report of the evolution of key study methods.

Promoting public access to clinical trial protocols: challenges and recommendations

BACKGROUND

Recognizing the value of promoting public access to clinical trial protocols, Trials pioneered the way for their publication over a decade ago. However, despite major advances in the public accessibility of information about trial methods and results, protocol sharing remains relatively rare.

MAIN BODY

Protocol sharing facilitates the critical appraisal of clinical trials and helps to identify and deter the selective reporting of outcomes and analyses. Challenges to the routine availability of high quality trial protocols include the gaps in incentives and adherence mechanisms, limited venues for sharing the original and final protocol versions, and the need for mechanisms to ensure transparent and complete protocol content.

CONCLUSIONS

We propose recommendations for addressing key challenges to protocol sharing in order to promote routine public access to protocols for the benefit of patients and other users of evidence from clinical trials.

Published intimate partner violence studies often differ from their trial registration records

INTRODUCTION

Registering study protocols in a trial registry is important for methodologic transparency and reducing selective reporting bias. The objective of this investigation was to determine whether published studies of intimate partner violence (IPV) that had been registered matched the registration record on key study design elements.

METHODS

We systematically searched three trial registries to identify registered IPV studies and the published literature for the associated publication. Two authors independently determined for each study whether key study elements in the registry matched those in the published paper.

RESULTS

We included 66 studies published between 2006 and 2017. Nearly half (29/66, 44%) were registered after study completion. Many (26/66, 39%) had discrepancies regarding the primary outcome, and nearly two-thirds (42/66, 64%) had discrepancies in secondary outcomes. Discrepancies in study design were less frequent (13/66, 20%). However, large changes in sample size (26/66, 39%) and discrepancies in funding source (28/66, 42%) were frequently observed.

CONCLUSIONS

Trial registries are important tools for research transparency and identifying and preventing outcome switching and selective outcome reporting bias. Published IPV studies often differ from their records in trial registries. Researchers should pay close attention to the accuracy of trial registry records.

Comparison of primary endpoints between publications, registries, and protocols of phase III cancer clinical trials

Background

Decisions by leading journals to require trial registration and to make protocols of phase III randomized clinical trials (RCTs) publicly accessible were landmark events in clinical trial reporting.

Materials and Methods

We identified phase III cancer RCTs published between 2013 and 2015 in New England Journal of Medicine (NEJM), The Lancet, The lancet Oncology, JAMA and Journal of Clinical Oncology (JCO).

Results

We identified 345 reports of phase III RCTs of which 217 (62.9%) had available protocols. The availability rates for NEJM, The Lancet, The Lancet Oncology, JAMA and JCO were 98.0%, 33.3%, 22.7%, 55.6% and 88.3%, respectively. Journal and publication year were significantly associated with protocol availability. Eight of 215 trials (3.7%) with English language protocols had a discrepancy in primary endpoints between publication and protocol. Discrepancies of primary endpoints between protocol and registration existed in 16 (7.7%) of 209 trials.

Conclusions

The policy of providing protocols with articles reporting RCTs has not been enforced rigorously. Selective reporting of primary endpoints only remains in a small fraction of phase III trials. Further improvement in consistency between primary endpoints registered and that in protocol is necessary.