Letter re: stratification by quality is not recommended in meta-analysis

We read with interest the letter by Page et  al. [1] who disagree with the conclusions of our paper, “Stratification by quality induced selection bias in a meta-analysis of clinical trials” [2]. Page et al. [1] critique the directed acyclic graph (DAG) we presented and suggest that conditioning on quality stratum does not imply that the results within strata defined by quality ranking are biased. We believe that bias occurs when studies are selected into strata such that systematic differences between larger and smaller studies emerge (where none initially existed), as shown in the funnel or Doi plot (Figures 2–4 in our publish ed article [2]).

Source: Journal of Clinical Epidemiology - June 6, 2019 Category: Epidemiology Authors: Jennifer Stone, Usha Gurunathan, Kathryn Glass, Zachary Munn, Peter Tugwell, Suhail A.R. Doi Tags: Letter to the Editor Source Type: research