Longitudinal impact of joint pain comorbidity on quality of life and activity levels in knee osteoarthritis: data from the Osteoarthritis Initiative

Objectives. Joint pain comorbidity (JPC) is common in individuals with knee OA. This study investigates the longitudinal association between JPC and health-related quality of life (HRQoL) and physical activity levels in individuals with knee OA. Methods. Data from the progression cohort of the Osteoarthritis Initiative (n = 1233; age 61 years and 58% females) were analysed. JPC was considered present if individuals reported pain in three or more joint groups, including the knee joints. HRQoL was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) Quality of Life subscale, and self-reported physical activity was determined using the Physical Activity Scale for the Elderly (PASE). Generalized estimating equation (GEE) analyses were performed, adjusted for age, sex, duration of complaints, medical comorbidity, and physical and mental functioning. Results. Over the 4-year period, 32% of participants never reported JPC, whereas 12% always reported JPC. GEE modelling demonstrated that having JPC was negatively associated with HRQoL [regression coefficient beta (95% CI) -3.57 (-4.69, -2.44)] and not associated with physical activity [-1.32 (-6.61, 3.98)]. Conclusion. Considering the impact of JPC on the HRQoL of individuals with knee OA, the assessment of JPC in individuals with knee OA might be a daily routine.