Choosing to report only the most impressive results from a clinical study, rather than all planned outcomes, could result in wasted research and potentially lead to biased conclusions and a lack of public trust in science. The issue of outcome reporting bias and initiatives designed to prevent it are discussed by Jamie Kirkham in an article published in The BMJ Opinion.
Dr Kirkham highlights that, according to a series published in The Lancet in 2014, up to 50% of planned study outcomes go unreported. Furthermore, in an article authored by Dr Kirkham and published in The BMJ in 2010, outcome reporting bias was found to have affected the conclusions of over a third of Cochrane systematic reviews. However, in recent decades, several initiates have been developed to improve outcome reporting. Prospectively registering clinical trials, as advocated by the International Committee of Medical Journal Editors (ICMJE) and WHO, is associated with the publication of trials that report the same primary outcomes as defined in the study protocol. In addition, reporting guidelines such as the Consolidated Standards of Reporting Trials (CONSORT) statement, have been designed to help researchers and editors determine which data to include in publications. However, while such guidelines have demonstrated some success, Dr Kirkham notes there is still room for improvement. One issue may be the large choice of measurable outcomes for researchers to choose from. The Core Outcome Measures in Effectiveness Trials (COMET) Initiative, is facilitating the development of a standardised set of core outcomes to be reported in clinical trials of specific conditions. Dr Kirkham also explains that useful tools intended to improve outcome reporting can be accessed via the Outcome Reporting Bias in Trials (ORBIT) website.
Dr Kirkham hopes that a combination of these initiatives and policies may ensure that clinical trial outcomes are reported appropriately to reduce bias. Ultimately, it is the responsibility of funders, authors, peer reviewers and editors to implement and adhere to such efforts.