Comparison of health-related quality of life, work status, and health care utilization and costs according to hip and knee joint disease severity: a national Australian study

BACKGROUND: No population-based studies have investigated how the impact of hip and knee joint disease may vary with increasing severity. OBJECTIVE: The purpose of this study was to evaluate health-related quality of life (HRQoL), work status, and health service utilization and costs according to severity of hip and knee joint disease. DESIGN: A national cross-sectional survey was conducted. METHODS: Five thousand individuals were randomly selected from the Australian electoral roll and invited to complete a questionnaire to screen for doctor-diagnosed hip arthritis, hip osteoarthritis (OA), knee arthritis, and knee OA. Severity was classified by means of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (range=0-100): <7=asymptomatic, 7-38=mild-moderate, and ≥39=severe. Health-related quality of life was evaluated by means of the Assessment of Quality of Life (AQoL) instrument (range=-0.04 to 1.00; scored worst-best). Self-reported data on work status and health service utilization were collected, with health care costs estimated with the use of government data. RESULTS: Data were available for 1,157 participants, with 237 (20%) reporting hip or knee joint disease. Of these, 16% (n=37) were classified as asymptomatic, 51% (n=120) as mild-moderate, and 27% (n=64) as severe. The severe group reported very low HRQoL (adjusted mean AQoL=0.43, 95% confidence interval [95% CI]=0.38-0.47) compared with the mild-moderate group (adjusted mean AQoL=0.72, 95% CI=0.69-0.75) and the asymptomatic group (adjusted mean AQoL=0.80, 95% CI=0.74-0.86). Compared with the asymptomatic group, the severe group was >3 times less likely to undertake paid work (adjusted odds ratio=0.28, 95% CI=0.09-0.88) and >4 times less likely to undertake unpaid work (adjusted odds ratio=0.24, 95% CI=0.10-0.62). Although physical therapy services were used infrequently, primary and specialist care utilization and costs were highest for the severe group. LIMITATIONS: Other costs (including physical therapy consultations) were unavailable. CONCLUSIONS: A clear pattern of worsening HRQoL, reduced work participation, and higher medical care utilization was seen with increasing severity of joint disease.