Pervasive Errors Due to Duplicate Trial Cohorts

With regard to the Original Investigation “Representativeness of Randomized Clinical Trial Cohorts in End-stage Kidney Disease: A Meta-analysis,” by Smyth et al,¹ published online July 8, 2019, Jiang et al² raised concerns about the inclusion of some of the trial cohorts in the meta-analysis and the possibility that some of these cohorts might be duplicates. Of the 6 pairs of cohorts identified by Jiang et al,² 4 are clearly distinct cohorts. However, 2 pairs represent duplicated cohorts, of which 1 cohort was published 3 times. The authors of the meta-analysis reanalyzed all the data based on 186 trials and 79 104 participants (ie, without the duplicated data) and found that the overall age, mortality rate, and study conclusions remain the same.³ The corrected analysis affects information in the original abstract, the Results and Discussion sections, Tables 1, 2, 3, and 4, the Figure, and the Supplement. This article was corrected online.