A review identified challenges distinguishing primary reports of randomized trials for meta-research: A proposal for improved reporting.

Meta-research is the discipline of studying research itself. A core investigative tool in meta-research is the use of systematic or scoping reviews to study the characteristics, methods and reporting of primary research studies. In the context of identifying eligible publications for methodological reviews of randomized controlled trials (RCTs), a challenge is to efficiently distinguish the primary trial report - which reports results for the primary outcome - from other types of reports, including design papers and secondary or supplementary analyses, or what we collectively refer to as non-primary reports. This may not be a straightforward task and may contribute to inefficiencies in the review process. Here, we draw on our recent methodological review of over 13,000 records to identify primary reports of pragmatic RCTs. We offer recommendations to improve the reporting of RCTs to facilitate more efficient identification of primary trial reports. We suggest that future updates to existing CONSORT guidelines include consideration of multiple trial reports and recommendations to clarify the primary or non-primary nature of each report. Our recommendations, together with improved adherence to inclusion of the trial registration number in the abstract and citation of a protocol or previously published primary report, would facilitate the conduct of methodological reviews.