Association of Knee Osteoarthritis with the Accumulation of Metabolic Risk Factors Such as Overweight, Hypertension, Dyslipidemia, and Impaired Glucose Tolerance in Japanese Men and Women: The ROAD Study

Objective. To clarify the association of knee osteoarthritis (KOA) with overweight (OW), hypertension (HTN), dyslipidemia (DL), and impaired glucose tolerance (IGT), which are components of metabolic syndrome (MS), in a Japanese population. Methods. We enrolled 1690 participants (596 men, 1094 women) from the large-scale cohort study Research on Osteoarthritis Against Disability (ROAD), begun in 2005 to clarify epidemiologic features of OA in Japan. KOA was evaluated by the Kellgren-Lawrence grade, minimum joint space width (MJSW), minimum joint space area (JSA), and osteophyte area (OPA). OW, HTN, DL, and IGT were assessed using standard criteria. Results. The prevalence of KOA in the total population in the age groups <= 39, 40-49,50-59, 60-69, 70-79, and >= 80 years was 2.2%, 10.7%, 28.2%, 50.8%, 69.0%, and 80.5%, respectively. Logistic regression analyses after adjustment for age, sex, regional difference, smoking habit, alcohol consumption, physical activities, regular exercise, and history of knee injuries revealed that the OR of KOA significantly increased according to the number of MS components present (1 component: OR 1.21,95% CI 0.88-1.68, p = 0.237; 2 components: OR 1.89,95% CI 1.33-2.70, p < 0.001: 3 or more components: OR 2.72,95% CI 1.77-4.18; p < 0.001). The number of MS components was inversely related to medial MSJW (beta = -0.148, R-2 = 0.21, p < 0.001), medial JSA (women only; beta = -0.096. R-2 = 0.18, p = 0.001), and positively related to OPA (beta = 0.12, R-2 = 0.11, p < 0.001). Conclusion. The accumulation of MS components is significantly related to presence of KOA. MS prevention may be useful to reduce cardiovascular disease and KOA risk. (First Release Feb 15 2011; J Rheumatol 2011;38:921-30; doi:10.3899/jrheum.100569)