Long-term health-related quality of life of total hip arthroplasty patients and cost-effectiveness analysis in the Japanese universal health insurance system

Aim: Total hip arthroplasty can effectively improve patients' motility with end-stage osteoarthritis. This study aimed to: (1) compare gradual changes in utility values with total hip arthroplasty and estimated values without; (2) evaluate total hip arthroplasty cost-effectiveness; and (3) evaluate cost-effectiveness by age, diagnosis, and comorbidity. Methods: Patients who underwent total hip arthroplasty between January 2008 and December 2009 were included. Patients completed the EuroQol preoperatively and at 1, 3, 5 and 7 years postoperatively. To derive the quality-adjusted life years gained, a utility score was obtained from the EuroQol item scores and combined with 7 years, and estimates were obtained by discounting the postoperative 1-year utility value at an annual rate of 2%–4%. Mixed-effects regression models were used to compare the estimated and the measured utility values. Results: Mean total cost was 1,921,849 yen, and quality-adjusted life years gain score was 1.746 with per cost as 1,100,715 yen. Compared with actual measurements, the estimated values from 1 to 7 years post-surgery differed significantly, and interaction was observed. Regarding age, the older the patient, the higher the cost per quality-adjusted life years. Patients with lower preoperative physical function had higher quality-adjusted life years gains, while the cost per quality-adjusted life years was lower. Conclusions: Total hip arthroplasty was cost-effective. Compared with actual measurements, the estimated utility values from 1 to 7 years post-surgery significantly differed. Even among older patients and those with impaired preoperative physical functions, its cost was lower than patients' willingness to pay in Japan.