Risk of knee osteoarthritis in patients with multiple atopic conditions: a nationwide study.

Knee osteoarthritis (OA) and atopic diseases are both characterized by chronic inflammation, yet their potential relationship remains unexplored. This study investigates whether atopic diseases are associated with an increased risk of knee OA in a large nationwide cohort. We conducted a nationwide cohort study using data from the Korean National Health Insurance Service (NHIS), including 880,300 individuals aged ≥ 50 years. Atopic disease was defined as ≥ 3 outpatient visits for asthma, allergic rhinitis, or atopic dermatitis. Knee OA incidence was identified using ICD-10 codes, and hazard ratios (HRs) were estimated using Cox proportional hazards models. Individuals with atopic diseases had a 36% higher risk of developing knee OA compared to those without (HR = 1.36, 95% CI: 1.35-1.37). A dose-response relationship was observed, with risk increasing progressively in individuals with multiple atopic conditions (HR = 1.44 for two conditions; HR = 1.51 for all three conditions). Subgroup analyses indicated that this association was strongest in younger individuals (50-59 years) and males. The results indicate a significant association between atopic diseases and an increased risk of knee OA, which was strongest in younger individuals. Further research is needed to understand the potential role of atopic-specific inflammation on OA development, and any potential implications for targeted therapies.