Prognosis of limitations in activities in osteoarthritis of the hip or knee: a 3-year cohort study.

OBJECTIVE: To describe the course of limitations in activities in elderly patients with osteoarthritis (OA) of the hip or knee over a follow-up period of 3 years, and to identify prognostic factors of the course of limitations in activities, focusing on body functions, comorbidity, and cognitive functioning. DESIGN: A longitudinal cohort study with 3 years of follow-up. Measurements were conducted annually. Statistical analyses included t tests, univariate regression analyses, and multivariate regression analyses. SETTING: Rehabilitation centers and hospitals (Departments of Orthopedics, Rheumatology, and Rehabilitation) in The Netherlands. PARTICIPANTS: Patients (N=237) with hip or knee OA. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Patient-perceived change, self-reported limitations in activities measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and observed limitations in activities (timed walking test). Prognostic factors: demographic data, clinical data, body function (pain, muscle strength, range of motion [ROM]), comorbidity, and cognitive functioning (cognitive decline, memory, attention). RESULTS: Self-reported limitations in activities measured by the WOMAC improved slightly after 3-year follow-up. In knee OA, reduced ROM at 1-year follow-up (beta=.120), increased pain at 1-year follow-up (beta=-.177), and higher morbidity count (beta=-.180) predicted worsening of self-reported limitations in activities. In hip OA, reduced ROM at 1-year follow-up (beta=.201 for hip external rotation and beta=.144 for knee extension), increased pain at 1-year follow-up (beta=-.134), higher morbidity count (beta=-.220), or the presence of moderate to severe cardiac disease (beta=-.214) and poorer cognitive functioning (beta=.181) predicted worsening of self-reported limitations in activities. Performance-based limitations in activities measured by the timed walking test did not change after 3 years of follow-up. In knee OA, decreased muscle strength at 1-year follow-up (beta=-.272) and higher morbidity count (beta=.199) predicted worsening of performance-based limitations in activities. In hip OA, better ROM (beta=.182), higher morbidity count (beta=.232), or the presence of moderate to severe cardiac and eye-ear-nose-throat disease (beta=.210 and beta=.188, respectively) and older age (beta=.355) predicted worsening of performance-based limitations in activities. CONCLUSIONS: Overall, at the group level, limitations in activities of patients with OA of the hip or knee recruited from hospitals and rehabilitation centers seem fairly stable during the first 3 years of follow-up. However, at the level of individual patients, considerable variation occurs. Prognostic factors for worsening of limitations in activities include increased pain, reduced ROM, and decreased muscle strength at 1-year follow-up; higher morbidity count; and to a lesser extent poor cognitive functioning. (aut. ref.)