Background: The objectives of this study were to investigate the prevalence rate of metabolic syndrome (MetS) among knee osteoarthritis (OA) patients in the Japanese general population, and to analyze the relationship between MetS and knee OA.
Methods: A total of 795 volunteers participated in this study. Based on the Kellgren-Lawrence (K-L) grade, participants were classified into two groups: the non-knee OA (non-KOA) group (K-L grade 0 or 1) or knee OA (KOA) group (grade 2-4). MetS was defined according to the Japanese Committee for the Diagnostic Criteria of MetS with a slight modification. The presence of hyperlipidemia, hypertension, diabetes mellitus and MetS were compared between the non-KOA and KOA groups. Furthermore, risk factors for MetS were analyzed by logistic regression analysis.
Results: The prevalence rate of hypertension in the KOA group was significantly higher than in the non-KOA group (P = 0.025) in males. Those of hypertension (P < 0.001), hyperlipidemia (P < 0.001) and diabetes mellitus (P = 0.019) in the KOA group were significantly higher than in the non-KOA group in females. Aging was significantly associated with MetS in males; the odds ratio (OR) for age was 1.033 (P = 0.020), suggesting that a 1-year increase in age raised the risk of MetS. In females, the presence of KOA was significantly associated with MetS; the risk of MetS in the KOA group was 2.196 (P = 0.034) fold the risk in the non-KOA group.
Conclusion: The prevalence rates of MetS and knee OA tended to increase with age in males; however, there was no association between MetS and knee OA. On the other hand, knee OA was significantly associated with MetS in females. Knee OA patients must be provided the best treatment approach because of their high risk for MetS, which promotes cardiovascular diseases.