Towards sex-specific osteoarthritis risk models: evaluation of risk factors for knee osteoarthritis in males and females.

OBJECTIVES The aim of this study was to identify sex-specific prevalence and strength of risk factors for the incidence of radiographic knee osteoarthritis (incRKOA). METHODS Our study population consisted of 10,958 Rotterdam Study participants free of knee OA in one/both knees at baseline. 1064 participants developed RKOA after a median follow-up time of 9.6 years. We estimated the association between each available risk factor and incRKOA using sex stratified multivariate regression models with generalized estimating equations. Subsequently, we statistically tested sex differences between risk estimates and calculated the population attributable fractions (PAFs) for modifiable risk factors. RESULTS The prevalence of the investigated risk factors was, in general, higher in women compared to men, except alcohol intake and smoking was higher in men and high BMI showed equal prevalence. We found significantly different risk estimates between men and women: high level of PA (RR 1.76, 95% CI 1.29-2.40) or a KL-score 1 at baseline (RR 5.48, 95% CI 4.51-6.65) was higher in men. Among borderline significantly different risk estimates was BMI ≥27, associated with higher risk for incRKOA in women (RR 2.00, 95% CI 1.74-2.31). The PAF for higher BMI was 25.6% in women and 19.3% in men. CONCLUSION We found sex-specific differences in both presence and relative risks of several risk factors for incRKOA. Especially BMI, a modifiable risk factor, impacts women more strongly than men. These risk factors can be used in the development of personalized prevention strategies and in building sex-specific prediction tools to identify high-risk profile patients.