Background Knee osteoarthritis affects mobility leading to substantial loss of perceived health and quality of life. Our previous study showed that aged persons with various comorbidities may profit from comprehensive rehabilitation in the short-term by corrected effect sizes up to 0.62 in pain, 0.51 in physical function, and 0.32 in psychosocial health (1).
Objectives To follow-up those patients to 5 years by 1) quantifying observed effects in pain, function, and psychosocial health and 2) associating risk factors to total knee arthroplasty during the observation period.
Methods Prospective cohort study with assessments at baseline (start of rehabilitation) and 1, 2, 3, 4, 5 years after. Comprehensive rehabilitation lasted 2–3 weeks for inpatients and 6 weeks for outpatients. Changes between baseline and the follow-ups were measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form 36 Health Survey (SF-36). They were expressed as effect sizes (ES) according to Kazis (2). Multivariate logistic regression included various sociodemographic and disease-modifying confounders and provided adjusted odds rations (OR) for the risk of getting total knee arthroplasty.
Results At baseline, n=205 knee osteoarthritis patients were included: 77.1% women, mean age 65.7 years (sd=10.3y), 81.5% having 3 or more comorbidities. Up to the 5 year follow-up, n=83 (40.5%) remained with complete data, 48 (23.4%) received arthroplasty. At 5 years, ES were 0.13 to 0.79 for pain, –0.12 (worsening) to 0.42 (improvement) for function, and –0.25 to 0.21 for psychosocial health. At the last follow-up before surgery, WOMAC pain had worsened by ES=–0.42 (p=0.001) and WOMAC function by ES=–0.54 (p=0.002) in the total knee arthroplasty group. Getting total knee arthroplasty was statistically significantly associated with female sex (OR=3.30), educated at university (OR=3.54), minus 1 comorbidity less (OR=1.41), and 10 (of 100 possible) points worsening on the WOMAC factor ascending/descending (OR=1.60).
Conclusions Moderate to small improvements on pain, function, and psychosocial health were observed up to 5 years after comprehensive rehabilitation of knee osteoarthritis. Nevertheless, almost one quarter of the participants were referred to total knee arthroplasty suffering from significant deterioration in pain and function. The WOMAC seems to be sensitive to predict the need for arthroplasty. Highly educated women with low number of comorbidities and high disability to manage stairs were more likely to receive total knee arthroplasty (3).
Angst F, Verra ML, Lehmann S, Benz T, Aeschlimann A. Effects of inpatient rehabilitation in hip and knee osteoarthritis. A naturalistic prospective cohort study with intra-individual control of effects. Arch Phys Med Rehabil 2013;94;2139–45.
Kazis ES, Anderson JJ, Meenan RF. Effect sizes for interpreting changes in health status. Med Care 1989;27(3 Suppl):S178–89.
Verra ML, Benz T, Lehmann S, Aeschlimann A, Winteler B, Angst F. Long-term outcome of knee osteoarthritis after comprehensive rehabilitation – 5 year follow up and risk for total knee arthroplasty. Journal 2017;in preparation.
Disclosure of Interest None declared