Increased Incidence of Spin and Reporting Bias on the Use of Hyaluronic Acid for the Treatment of Knee Osteoarthritis: An Evaluation of Systematic Reviews and Meta-Analyses.

Background: The use of hyaluronic acid (HA) for the treatment of knee osteoarthritis holds clinical and financial implications for manufacturers, incentivizing spin, or the misrepresentation of study findings. We sought to identify the incidence of spin in abstracts of systematic reviews and meta-analyses evaluating the efficacy of HA injections used for the treatment of knee osteoarthritis.

Methods: Systematic reviews and meta-analyses reporting on HA for knee osteoarthritis were extracted through a Preferred Reporting Items for Systematic Reviews and Meta-Analyses search of Embase, PubMed, and Cochrane databases. After two independent authors performed screening and data extraction, abstracts were evaluated for the 21 most common types of spin as reported by Yavchitz et al. Year and journal of publication, level of evidence, study design, funding source, adherence to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and SCOPUS CiteScore were collected. Descriptive variable associations, calculated using Chi-square analyses, identified relationships between common spin types and abstract characteristics.

Results: At least one type of spin was identified in 112 out of 114 extracted studies, with an average spin score of 5.07 ± 2.59 per publication. The most common spin type was "conclusion claiming beneficial effect of experimental treatment despite high risk of bias in primary studies" (98 of 114, 86.0%). A statistically significant association was found between older publication year and spin type, "authors hide or do not present any conflict of interest" (P = 0.011). There was a significant association between lower levels of evidence and "failure to report a wide confidence interval of estimates" (P = 0.002) and "failure to report the number of studies/patients contributing to the analysis for main outcomes" (P = 0.041).

Conclusions: Our findings demonstrated a high incidence of spin among systematic reviews and meta-analyses evaluating the efficacy of HA injections used for the treatment of knee osteoarthritis. Careful evaluation of misleading reporting in current literature is warranted when considering this treatment.