Candidate for the Lee B. Lusted Student Prize Competition
Purpose: To assess the cost-effectiveness of manual therapy, exercise, and manual therapy and exercise combined versus usual care in patients with hip and/or knee osteoarthritis (OA).
Method: A cost-utility analysis from the health care perspective was performed alongside the Management of Osteoarthritis (MOA) Trial (n=206). Each participant in a treatment group was scheduled for 9 individually supervised physical therapy treatments. The manual therapy group focused on increasing mobility through manually implemented forces at the joint and surrounding structures. The exercise group focused on increasing strength and mobility, and manual therapy and exercise group was a combination of both treatments. All interventions were in addition to usual care. The main outcome measures of the cost-utility analysis were total health care cost (unit costs estimated from a combination of published and unpublished sources, presented in 2008 USD) and quality adjusted life years (QALY) at 12 months; QALYs were estimated from the SF-12. Multivariate analyses were performed using generalized linear models with a power 2.0 link and Poisson family. Incremental cost effectiveness ratios (ICER) and 95% CIs and cost-effectiveness acceptability curves (CEAC) were reported. Mean differences between groups and 95% CIs were obtained by bootstrap regressions (2000 replications). A willingness to pay (WTP) threshold of $50,000 was used to judge good value for money. CEACs were calculated for WTP thresholds of up to $100,000 per QALY.
Result: The addition of individually supervised physical therapy to usual care resulted in an increase in QALYs and higher costs for all treatment groups at 12 months. Health care costs were $166.54 higher than usual care in the manual therapy treatment and the ICER was $41,761 (9113.05, -14800.20). For the exercise group, total costs were $341.35 higher than usual care and the ICER was $42,276.12 (9250.48, -15072). The combined therapy treatment group also resulted in higher costs when compared with usual care ($522.98) and an ICER estimate of $42,643.21 (9359.20, -15302.80). For all groups, at a WTP of $100,000, probabilities of cost-effectiveness reached 63%.
Conclusion: The cost-effectiveness estimates for each treatment group fell below the $50,000 threshold, indicating good value, however a large degree of uncertainty surrounds these estimates.