Clinical studies are often at risk of spin, a form of bias where beneficial claims are overstated while negative findings are minimized or dismissed. Spin is often more problematic in abstracts given their brevity and can result in the misrepresentation of a study’s actual findings. The goal of this study is to aggregate primary and secondary studies reporting the clinical outcomes of the use of sub-acromial balloon spacers in the treatment of massive, irreparable rotator cuff tears (MIRCTs) to identify the incidence of spin and find any significant association with study design parameters.
This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Independent searches were completed on two databases (PubMed and Embase) for primary studies, systematic and current concepts reviews, and meta-analyses and the results were compiled. Two authors independently screened the studies using a predetermined inclusion criteria and aggregated data including titles, publication journals and years, authors, study design, etc. Each study was independently assessed for the presence of 15 different types of spin. Statistical analysis was conducted to identify associations between study characteristics and spin.
29 studies met the inclusion criteria for our analysis, of which 10 were reviews or meta-analyses and 19 were primary studies. Spin was identified in every study except for 2 (27/29, 93.1%). Type 3 spin, “Selective reporting of or overemphasis on efficacy outcomes or analysis favoring the beneficial effect of the experimental intervention” and type 9 spin, “Conclusion claims the beneficial effect of the experimental treatment despite reporting bias” were most frequently noted in our study, both observed in 12/29 studies (41.4%). Scopus CiteScores, date of publication, and adherence to PRISMA or PROSPERO were study characteristics associated with a higher rate of certain types of spin. There was a statistically significant association between disclosure of external study funding source and the presence of spin type 4, but none of the other forms of spin.
– Spin is highly prevalent in the abstracts of primary studies, systematic reviews, and meta-analyses discussing the use of subacromial balloon spacer technology in the treatment of massive, irreparable rotator cuff tears. Our findings revealed that spin in the abstract tended to favor the balloon spacer intervention. Further efforts are required in the future to mitigate spin within the abstracts of published manuscripts.

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