Evaluation of spin in systematic reviews and meta-analyses of superior capsular reconstruction.

Background: Small, preliminary studies and the systematic reviews on superior capsular reconstruction (SCR) that collate data are at increased risk spin. This study's primary objective was to identify, describe, and account for the incidence of spin in systematic reviews of SCR. This study's secondary objective was to characterize the studies in which spin was identified to determine whether identifiable patterns of characteristics exist among studies with spin.

Methods: This study was conducted per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using a predetermined protocol. A search was conducted on the PubMed and Embase databases for systematic reviews and meta-analyses on SCR. Screening and data extraction were conducted independently by 2 authors. Each included study's abstract was assessed for the presence of the 15 most common types of spin, with full texts reviewed during cases of disagreement or for clarification. General data that were extracted included study title, authors, publication year, journal, level of evidence, study design, funding source, reported adherence to PRISMA guidelines, preregistration of the study protocol, and primary and secondary outcome measures. Full texts were used in the assessment of study quality per AMSTAR 2.

Results: We identified 53 studies during our search, of which 17 met the inclusion criteria. At least 1 form of spin was observed in all 17 studies. The most common types of spin were type 5 ("The conclusion claims the beneficial effect of the experimental treatment despite a high risk of bias in primary studies") and type 9 ("Conclusion claims the beneficial effect of the experimental treatment despite reporting bias"), both of which were observed in 11 studies (11 of 17, 65%). A statistically significant association between lower level of evidence and type 5 ("The conclusion claims the beneficial effect of the experimental treatment despite a high risk of bias in primary studies") was observed (P = .0175). A statistically significant association was also found between more recent year of publication and the spin category misleading interpretation (P = .0398), and between lower AMSTAR 2 score and type 13 ("Failure to specify the direction of the effect when it favors the control intervention") (P = .0260). No other statistical associations between other study characteristics were observed.

Conclusion: Spin is highly prevalent in abstracts of SCR systematic reviews and meta-analyses. An association was found between the presence of spin and lower level of evidence, year of publication, and AMSTAR 2 ratings.