Comparison of Clinical Trial Changes in Primary Outcome and Reported Intervention Effect Size Between Trial Registration and Publication. JAMA Network Open 2019

This review found inconsistencies between registered and published primary outcomes of clinical trials were common, and trials with primary outcome change are likely to have a larger intervention effect than those without. Compared with those without primary outcome change, trials with primary outcome change showed a 16% (pooled ROR, 0.84; 95% CI, 0.73-0.96) larger reported intervention effect size.