A COST-EFFECTIVENESS ANALYSIS OF TOTAL HIP-ARTHROPLASTY FOR OSTEOARTHRITIS OF THE HIP

Objective.-To quantify the trade-off between the expected increased sh ort- and long-term costs and the expected increase in quality-adjusted life expectancy (QALE) associated with total hip arthroplasty (THA) f or persons with functionally significant hip osteoarthritis. Design.-A cost-effectiveness study was performed from the societal perspective by constructing stochastic tree, decision analytic models designed to estimate lifetime functional outcomes and costs of THA and nonoperativ e managements. Main Outcome Measures.-A modified four-state American C ollege of Rheumatology functional status classification was used to me asure effectiveness. These functional classes were assigned utility va lues to allow the relative effectiveness of THA to be expressed in qua lity-adjusted life years (QALYs), Lifetime costs included costs associ ated with primary and potential revision surgeries and long-term care costs associated with the functionally dependent class. Data Used in t he Cost-effectiveness Model.-Probability and incidence rate data were summarized from the literature. The THA hospital cost data were obtain ed from local teaching hospitals' cost accounting systems, Estimates o f recurring medical costs for functionally significant hip osteoarthri tis and for custodial care were derived from the literature. Results.- The THA cost-effectiveness ratio increases with age and is higher for men than for women, In the base-case scenario for 60-year-old white wo men who have functionally significant but not dependent hip osteoarthr itis, the model predicts that THA is cost saving because of the high c osts of custodial care associated with dependency due to worsening hip osteoarthritis and that the procedure increases QALE by about 6.9 yea rs. In the base-case scenario for men aged 85 years and older, the ave rage lifetime cost associated with THA is $9100 more than nonoperative management, with an average increase in QALE of about 2 years. Thus, the THA cost-effectiveness ratio for men aged 85 years and older is $4 600 per QALY gained, less than that of procedures intended to extend l ife such as coronary artery bypass surgery or renal dialysis, Worst-ca se analysis suggests that THA remains minimally cost-effective for thi s oldest age category ($80 000/QALY) even if probabilities, rates, uti lities, costs, and the discount rate are simultaneously varied to extr eme values that bias the analysis against surgery. Conclusions.-For pe rsons with hip osteoarthritis associated with significant functional l imitation, THA can be cost saving or, at worst, cost-effective in impr oving QALE when both short- and long-term outcomes are considered, Fur ther research is needed to determine whether this procedure is actuall y being used in this cost-effective manner, especially in older age ca tegories.