Risk factors for progression of radiographic knee osteoarthritis in elderly community residents in Korea

BACKGROUND Knee osteoarthritis (OA) is the most common form of arthritis affecting the elderly. Understanding the risk factors for knee OA has been derived from cross sectional studies. There have been few longitudinal studies of risk factors for knee OA among Asian populations. The purpose of this study was to evaluate the risk factors for knee OA in elderly Korean community residents. METHODS This prospective, population-based study was conducted on residents over 50 years of age in Chuncheon who participated in the Hallym Aging Study. Standardized weight-bearing semi-flexed knee anteroposterior radiographs were obtained in 2007 and in 2010. Of 504 participants at baseline, 322 participants (male: female = 150:172) underwent follow-up knee radiographs. Radiographic knee OA was defined as Kellgren/Lawrence (K-L) grade of ≥ 2. Risk factors assessed at baseline were tested for their association with incidence, progression, and worsening of radiographic knee OA by logistic regression analysis. RESULTS The median age of these participants at follow-up was 71 years (interquartile range 66-75 years). Incident OA was observed in 33 (10.2%) and progression of OA (defined as an increase of Kellgren-Lawrence (K-L) grade at follow-up, from grades 2 or 3 at baseline) in 43 (13.55%) participants. In multivariate logistic regression analysis, only females were significantly associated with the progression of radiographic knee OA (odds ratio [OR] = 4.41, 95% confidence interval [CI] 1.32-14.77). CONCLUSIONS In this 3-year longitudinal study, the yearly incidence and progression of knee OA was higher than those previously reported in Western populations.