Determinants of willingness to pay for hip and knee joint replacement surgery for osteoarthritis.

OBJECTIVES: To determine whether patients with osteoarthritis (OA) would be willing to pay for joint replacement and whether patient characteristics or health outcomes, including pain, physical function and health-related quality of life, were related to willingness to pay (WTP).

METHODS: Patients who had undergone primary total hip replacement (THR) or total knee replacement (TKR) for OA completed a disease-specific questionnaire (Western Ontario and McMaster: WOMAC index), a generic measure of health status (Medical Outcome Study Short Form-36: SF-36) and an Evaluation Questionnaire to measure WTP and satisfaction with the replacement.

RESULTS: Responses were obtained from 109 (77%) THR patients and 129 (72%) TKR patients. Mean age of respondents was 67 yr for THR (47% female) and 73 yr for TKR (60% female). Overall, 85% of patients responded to the WTP question. Of the THR patients, 71% were willing to pay something, 11% were not willing to pay anything and 18% did not answer the question. For TKR patients these figures were 70, 16 and 14% respectively. However, of those who responded to the WTP question, only 25% of the THR patients and 18% of the TKR patients indicated they would be willing to pay the actual current average cost of the operation in Australia (>/= A$15 000). A lower postoperative pain score (as measured by the WOMAC index) was a significant predictor of WTP for both THR and TKR patients. Income also significantly predicted WTP in THR patients but not in TKR patients. The other significant predictors for TKR patients were older age, having private health insurance and willingness to recommend joint replacement to others.

CONCLUSIONS: Willingness to pay was a measure that was understandable and acceptable to patients, most of whom were willing to pay something. There was a high correlation between WTP, good health outcomes and patient satisfaction, pain relief being the dominant determinant.