Methodological quality was critically low in 9/10 systematic reviews in advanced cancer patients - a methodological study.

Abstract Objective : To assess the methodological quality and the consideration of heterogeneity in systematic reviews (SRs). Study Design and Setting : We conducted a methodological study (CRD42019134904) and searched three databases from January 2010 to July 2019. Interventional SRs with a statistically significant meta-analysis of at least four randomized controlled trials in advanced cancer patients were included. A MeaSurement Tool to Assess Systematic Reviews (AMSTAR) 2 was used to evaluate the SRs’ methodological quality. The consideration of heterogeneity was categorized in clinical or/and methodological heterogeneity and not explored. Results : From 6234 identified references, 261 SRs were included. Most SRs had a critically low quality (230, 88.1%). The majority of them (209, 80.1%) was classified as critically low because of non-registration (222, 85.1%) combined with the non-reporting of excluded full-texts and missing justifications for exclusion (218, 83.5%). Heterogeneity in trial results was not explored at all in 51 (19.5%) SRs whereas clinical heterogeneity was considered in 117 (44.8%), methodological heterogeneity in 13 (5.0%), and both clinical and methodological heterogeneity in 80 (30.7%) SRs. Conclusion : The consideration of these findings in trainings for review authors and peer reviewers could improve the awareness of quality criteria and the quality of future SRs. Trial registration : PROSPERO-ID: CRD42019134904