Physical activity status by pain severity in patients with knee osteoarthritis: a nationwide study in Korea

Few reports have explored the extent to which physical activity is affected by pain severity in knee osteoarthritis (KOA) patients. We used national representative data to investigate the physical activity of KOA patients compared to the general population to determine what proportion of patients met physical activity recommendations and to explore how the proportion changes with pain severity.

We used data from the fifth Korean National Health and Nutrition Examination Survey (KNHANES V; 2010-2012). In total, 1279 participants aged ≥50 years who had radiographic KOA and who evaluated knee pain on a numerical rating scale were selected. KOA was assessed using the Kellgren-Lawrence system. The Korean short version of the International Physical Activity Questionnaire was used to measure physical activity status. We used the physical activity recommendations of the American College of Rheumatology Work Group Panel when evaluating the extent of activity in KOA patients.

Only 18.6% of KOA patients met the osteoarthritis expert panel recommendations, lower than in the general population (23.2%; p = 0.003). The percentages that met the recommendations in the none to mild pain group, moderate pain group, and severe pain group were 23.4%, 17.6%, and 18.3%, respectively (p = 0.341). In terms of flexibility, a somewhat higher percentage of those with moderate pain engaged in physical activity compared to those with little or no pain (17.1% vs. 12.3%), but the difference was not significant (p = 0.585).

Regardless of pain severity, overall physical activity was suboptimal in Korean KOA patients. It is important to emphasize to osteoarthritis patients in clinical settings the need for physical activity, and a policy-based effort is required to facilitate appropriate exercise.