High variability in results and methodological quality among overlapping systematic reviews on the same topics in surgery: a meta-epidemiological study.

BACKGROUND Redundant publication of systematic reviews and meta-analyses (SRs/MAs) on the same topic presents an increasing burden for clinicians. The aim of this study was to describe variabilities in effect size and methodological quality of overlapping surgery-related SRs/MAs and to investigate factors associated with their postpublication citations. METHODS PubMed/MEDLINE was searched to identify SRs/MAs of RCTs on thoracoabdominal surgeries published in 2015. Previous SRs/MAs on the same topics published within the preceding 5 years (2011-2015) were identified and 5-year citation counts (through to 2020) were evaluated. Discrepancies in pooled effect sizes and their methodological quality using A Measurement Tool to Assess Systematic Reviews (AMSTAR) among overlapping SRs/MAs were assessed. The SR/MA-level factors associated with 5-year citation counts were explored, using a mixed-effects regression model with a random intercept for surgical topics. RESULTS A total of 57 surgery-related SRs/MAs (48 topics) published in 2015 were identified, and 146 SRs/MAs had overlapping publications on 29 topics (60.4 per cent of all topics) in the preceding 5 years. There was considerable variability in methodological quality of SRs/MAs and coverage probability for relevant RCTs, resulting in discrepant effect size estimates for the same topic. High quality (AMSTAR score 8-11) was independently associated with higher 5-year citation counts (coefficient = 32.82; 95 per cent c.i. 15.63 to 50.02; P < 0.001). CONCLUSION Overlapping SRs/MAs with high variability in results and methodological quality were common in surgery. A high-quality SR/MA score was an independent predictor of more frequent citations. Researchers and journal editors should concentrate their efforts on limiting publications to higher-quality reviews.