Transparency in Reporting Results From Randomized Clinical Trials Robert Kaplan 1 , Veronica Irvin 2 1 Corresponding author. Stanford University. Stanford, California, United States of America. Bob.Kaplan@stanford.edu 2 Oregon State University. Corvallis, Oregon, United States of America. veronica.irvin@gmail.com Critical appraisal of evidence Submitted 01/31/2019, Accepted 04/17/2019, Published 06/13/2019 J. Évid-Based Healthc., Salvador, 2019 June;1(1):50-51 Designated editor: Luís Cláudio Lemos Correia How to cite this article: Kaplan R, Irvin V. Transparency in Reporting Results From Randomized Clinical Trials. J Évid-Based Healthc.. 2019;1(1):50-51. The interpretation of randomized clinical trials has been hindered by selective reporting bias 1 . In the USA, nearly 90% of industry sponsored trials report positive results, in comparison to only about half of government supported trials. Even in government sponsored studies, only about 46% of US NIH funded studies were published within 30 months of completion. Clinicians want to know the percentage of studies that support the use of a particular treatment 2 . But, it is difficult to calculate this percentage because the denominator for the analysis is unknown. To address this problem, we examined all of the large randomized clinical trials funded by the US National Heart, Lung, and Blood Institute (NHLBI) over the 40 years ending in 2013 3 . Results from large trials (budget > US$ 500,000/year) are known to be more likely to be published 2 . We were particularly interested in whether the trials reported a significant benefit of treatment for the primary outcome that the investigators used to justify the study. For example, the primary outcome variable might be death from myocardial infarction or death from any cause. 55 large trials on heart disease treatments met the inclusion criteria. We found that trials were more likely to produce a positive result if they were published prior to the year 2000. Prior to the 2000 positive results occurred in 57% of the published studies. Following the year 2000, the success rate plunged to just 8%. Figure 1 plots the relative risks of the primary outcome by the publication year of the main outcome paper. The Cardiac Arrhythmia Suppression Trial (CAST) study was excluded from the Figure because it was an outlier in which there was an abruptly high mortality rate among those receiving the active treatment. Studies published prior to 2000 frequently reported that treatments were effective in comparison to control conditions. One important deviation was the CAST trial, which demonstrated significant harm of arrhythmia suppression. There was a significant change in the probability or reporting positive results after 2000. As shown in Figure 1, nearly all studies, reported null effects, The two exceptions were PREVENT and the SANDS trials which reported benefits and and the Women’s Health Initiative which reported harm. Further, quantitative estimemates of treatment effect sizes declined for studies published after 2000. Of particular interest, following the year 2000, no study reported a significant benefit for all- cause mortality. After our review was reported in 2015, the SPRINT Trial became the first large NHLBI trial in 20 years to show a positive effect for all cause mortality 4 .