The prevalence of osteoarthritis and risk factors in the Korean population: The Sixth Korea National Health and Nutrition Examination Survey (VI-1, 2013)

Background: Knee osteoarthritis is highly prevalent, especially among the elderly. However, its risk factors have not been well identified, especially in the Korean population. This study aimed to assess the epidemiologic characteristics and risk factors of knee osteoarthritis in the Korean population. Methods: Data of 2,280 (1,295 women) participants of the 2013 Korea National Health and Nutrition Examination Survey aged ≥50 years who underwent knee radiography were analyzed. According to the American College of Rheumatology clinical/radiographic classification criteria, knee osteoarthritis was defined as knee pain and radiographic knee osteoarthritis. The association between risk factors and knee osteoarthritis was analyzed using the chi-square test and binominal logistic regression. Results: The participants had an average age of 62.6 years; 56.8% of them were women. The average body mass index was 24.2 kg/m², and 296 (13%) participants were diagnosed with knee osteoarthritis. After adjustment for multiple risk factors, age of ≥65 years (adjusted odds ratio [OR], 2.552; 95% confidence interval [CI], 1.868-3.486), female sex (OR, 2.050; 95% CI, 1.275-3.295), obesity (body mass index, ≥25.0 kg/m²; OR, 1.563; 95% CI, 1.191-2.051), hypertension (OR, 1.394; 95% CI, 1.052-1.846), low educational level (lower than or equal to elementary school: OR, 4.761; 95% CI, 2.131-10.635; middle school: OR, 3.184; 95% CI, 1.375-7.369), and low strength exercise frequency (< 2 times/wk; OR, 1.829; 95% CI, 1.202-2.784) increased the risk of knee osteoarthritis. Conclusion: Old age, sex, obesity, hypertension, low educational level, and low strength exercise frequency were found to be risk factors for knee osteoarthritis.