Metabolic syndrome, accumulation of its components and risk of knee and hip replacement for osteoarthritis in community-dwelling older adults.

Objective: To examined whether metabolic syndrome (MetS) and accumulation of its components were associated with incidence of knee and hip replacement for osteoarthritis in community-dwelling older individuals. Design: This study examined 9179 women and 7524 men from the ASPREE trial. MetS was defined if at least three of the five criteria were present: central obesity, elevated triglyceride, reduced high-density lipoprotein cholesterol, hypertension, and dysglycemia. Knee and hip replacement for osteoarthritis were defined by hospitalisations during the ASPREE trial for knee and hip surgical procedures with the indication recorded as osteoarthritis. Results: Over a mean follow-up of 4.0 (standard deviation 1.4) years, 547 women and 346 men had knee replacements and 404 women and 290 men had hip replacements. Central obesity was associated with an increased risk of knee replacement in women [hazard ratio (HR) 1.62, 95 ​% confidence interval (CI) 1.26-2.10] but not men (HR 0.93, 95 ​% CI 0.70-1.23), independent of confounders including body mass index. MetS was independently associated with a decreased risk of hip replacement in men (HR 0.73, 95 ​% CI 0.57-0.95) but not women (HR 0.90, 95 ​% CI 0.73-1.12). Accumulation of MetS components was also associated with a decreased risk of hip replacement in men (p for trend 0.005) which was not seen in women (p for trend 0.94). Conclusion: These findings suggest that targeting central obesity may reduce the risk of knee replacement in older women. The mechanism for the reduced risk of hip replacement in men associated with MetS and accumulation of MetS components is unclear and warrants further investigations.