What Is the Evidence to Support the Association Between Metabolic Syndrome and Osteoarthritis? A Systematic Review

Objective There is conflicting evidence on the association between metabolic syndrome (MetS) with the risk of osteoarthritis (OA). We aimed to systematically summarize the empirical evidence and discuss challenges in research methodologies in addressing this question. Methods We performed a systematic literature review based on PubMed, Embase, Web of Science, and the Cochrane Database of Systematic Reviews on published epidemiologic studies that examined the association between MetS and the risk of OA. We included cross-sectional studies, case-control studies, and cohort studies with appropriate covariate adjustments. We extracted information on prevalence, incidence, crude and adjusted effect estimates, and the 95% confidence intervals from the articles, or this information was provided by the authors. We listed the main methodologic issues existing in current literature and provided recommendations for future research on this topic. Results We identified 7 eligible studies on knee OA, 3 on hip OA, and 3 on hand OA. In studies that adjusted for body mass index or weight, MetS was not significantly associated with the risk of knee OA. No significant associations were reported for hip OA. For hand OA, the data were sparse and insufficient to reach a conclusion. Studies were mostly cross-sectional, exposure included only 1 time measurement, few studies had incident outcomes, and covariate adjustment was often insufficient. Conclusion Our review was unable to reach a definitive conclusion due to insufficient data, although the data suggest that knee and hip OA are not associated with MetS. Future longitudinal studies with incident OA cases, repeated measurement of MetS, and appropriate covariate adjustment are needed.