Risk of bias and methodological appraisal practices in systematic reviews published in anaesthetic journals: a meta‐epidemiological study

The validity of primary study results included in systematic reviews plays an important role in drawing conclusions about intervention effectiveness and carries implications for clinical decision‐making. We evaluated the prevalence of methodological quality and risk of bias assessments in systematic reviews published in the five highest‐ranked anaesthesia journals since 2007. The initial PubMed search yielded 315 citations, and our final sample after screening consisted of 207 systematic reviews. One hundred and seventy‐four reviews conducted methodological quality/risk of bias analyses. The Jadad scale was most frequently used. Forty‐four of the 83 reviews that included high risk of bias studies re‐analysed their data omitting these trials: 20 showed differences in pooled effect estimates. Reviews containing a greater number of primary studies evaluated quality less frequently than smaller reviews. Overall, the majority of reviews evaluated bias; however, many applied questionable methods. Given the potential effects of bias on summary outcomes, greater attention is warranted.