Availability of study protocols for randomized trials published in high-impact medical journals: A cross-sectional analysis.

Abstract

All randomized clinical trials published in Annals of Internal Medicine, BMJ, JAMA, Lancet, and NEJM in 2016 were identified. For each randomized clinical trial, we searched for protocols and statistical analysis plans on journal websites (including supplementary material) and in the article, for example, a referenced publication or link to trial or institutional website. Characteristics of randomized clinical trials were extracted from the publication and clinical trial registry. A detailed assessment of protocols and statistical analysis plans was conducted in a 20% random sample of randomized clinical trials.