[Selective reporting of positive outcomes in randomised trials--secondary publication.. A comparison of protocols with published reports].
Hróbjartsson A., Chan A-W., Haahr MT., Gøtzsche PC., Altman DG.
INTRODUCTION: Selective reporting of positive outcomes is associated with bias. MATERIALS AND METHODS: We conducted a cohort study of 102 protocols of randomised trials approved by the Scientific Ethics Committees for Copenhagen and Frederiksberg in 1994-1995 and the corresponding 122 reports. RESULTS: The median proportion of incompletely reported outcomes per trial was 50%. Statistically significant outcomes were more often fully reported, odds ratio 2.4. In 62% of trials, at least one primary outcome was changed. DISCUSSION: Outcomes in randomised trials are often reported selectively.