Methodological Quality of Systematic Reviews and Meta-Analysis on Asthma Treatments. A Cross-Sectional Study

Rationale: Systematic reviews (SRs) provide the best evidence of the effectiveness of treatment strategies for asthma. Carefully conducted SRs provide high-quality evidence for supporting decision-making, but the trustworthiness of conclusions can be hampered by limitation in rigor.Objectives: To appraise the methodological quality of a representative sample of SRs on asthma treatments in a cross-sectional study.Methods: A cross-sectional study was conducted to identify SRs on asthma treatment published between 2013 and 2019 by searching the Cochrane Database of Systematic Reviews, Embase, MEDLINE, and PsycINFO. SRs including at least one meta-analysis on asthma treatments were included. Methodological quality of included SRs was assessed with the Assessing the Methodological Quality of Systematic Reviews 2 instrument. Factors associated with methodological quality were explored using multivariate regression analysis.Results: One hundred thirty-six SRs were included and appraised, with a majority being non-Cochrane reviews (71.3%). Only 12 (8.8%) were of high overall quality; 9 (6.6%), 32 (23.5%), and 83 (61.0%) were of moderate, low, and critically low overall quality, respectively. More specifically, no SRs (0.0%) conducted a comprehensive literature search; only 3 (2.2%) justified why a particular primary study design was selected; 37 (27.2%) reported sources of funding among included studies; and 54 (39.7%) provided lists of excluded studies with justification. Cochrane reviews (adjusted odds ratio, 36.56; 95% confidence interval, 10.49-127.42) and SRs published after 2017 (adjusted odds ratio, 4.52; 95% confidence interval, 1.73-11.83) were positively associated with higher methodological quality.Conclusions: Methodological quality of SRs on asthma treatments are suboptimal. Future SRs should be improved by conducting comprehensive literature searches, justifying study design selection, providing a list of excluded studies, and reporting funding sources of included studies.