Metabolic syndrome and knee osteoarthritis: associations with disease stage and pain.

Objectives: Metabolic Syndrome (MetS) is associated with OA progression and pain. However, its relationship with outcomes in early-stage disease remains unclear. We assessed associations of MetS with radiographic stage and knee pain in individuals with symptomatic knee OA. Methods: We analysed cross-sectional baseline data from 251 participants in the Western Ontario Registry for Early Osteoarthritis (WOREO) Knee Study. Associations between MetS and radiographic stage were assessed using modified Poisson regression. Associations with knee pain, measured by the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain scale, were evaluated using multiple linear regression accounting for within-participant correlation. Analyses were stratified by OA stage and adjusted for body mass index (BMI). Results: MetS was associated with a higher prevalence of late-stage knee OA [adjusted prevalence ratio 1.45 (95% CI 1.16, 1.81)]. After BMI adjustment, hypertension and haemoglobin A1c remained associated with late-stage disease. Participants with MetS reported worse knee pain, with lower KOOS pain scores [β = -14.70 (95% CI -20.92, -8.47)], particularly in early-stage disease [β = -14.15 (95% CI -20.37, -7.93)]. Dyslipidaemia (elevated triglycerides and reduced high-density lipoprotein cholesterol were also associated with worse pain in early-stage disease. Conclusion: MetS and its components are associated with greater radiographic severity and clinically meaningful worsening of pain, especially in early-stage knee OA, independent of BMI. These findings suggest that early identification and management of metabolic disease may represent a modifiable target to improve OA outcomes.