Does masking author identity improve peer review quality? - A randomized controlled trial

Context.-All authors may not be equal in the eyes of reviewers. Specifically, well-known authors may receive less objective (poorer quality) reviews. One study at a single journal found a small improvement in review quality when reviewers were masked to author identity. Objectives.-To determine whether masking reviewers to author identity is generally associated with higher quality of review at biomedical journals, and to determine the success of routine masking techniques. Design and Setting.-A randomized controlled trial performed on external reviews of manuscripts submitted to Annals of Emergency Medicine, Annals of Internal Medicine, JAMA, Obstetrics & Gynecology, and Ophthalmology. Interventions.-Two peers reviewed each manuscript. In one study arm, both peer reviewers received the manuscript according to usual masking practice. In the other arm, one reviewer was randomized to receive a manuscript with author identity masked, and the other reviewer received an unmasked manuscript. Main Outcome Measure.-Review quality on a 5-point Likert scale as judged by manuscript author and editor. A difference of 0.5 or greater was considered important. Results.-A total of 118 manuscripts were randomized, 26 to usual practice and 92 to intervention. In the intervention arm, editor quality assessment was complete for 77 (84%) of 92 manuscripts. Author quality assessment was complete on 40 (54%) of 74 manuscripts. Authors and editors perceived no significant difference in quality between masked (mean difference, 0.1; 95% confidence interval [CI], -0.2 to 0.4) and unmasked (mean difference, -0.1;95% CI, -0.5 to 0.4) reviews. We also found no difference in the degree to which the review influenced the editorial decision (mean difference, -0.1;95% CI,-0.3 to 0.3). Masking was often unsuccessful (overall, 68% successfully masked; 95% CI, 58%-77%), although 1 journal had significantly better masking success than others (90% successfully masked; 95% CI, 73%-98%). Manuscripts by generally known authors were less likely to be successfully masked (odds ratio, 0.3; 95% CI, 0.1-0.8). When analysis was restricted to manuscripts that were successfully masked, review quality as assessed by editors and authors still did not differ. Conclusions.-Masking reviewers to author identity as commonly practiced does not improve quality of reviews. Since manuscripts of well-known authors are more difficult to mask, and those manuscripts may be more likely to benefit from masking, the inability to mask reviewers to the identity of well-known authors may have contributed to the lack of effect.