The cost-effectiveness of risedronate treatment in Japanese women with osteoporosis

We constructed a mathematical model for assessing the cost-effectiveness of providing BMD (bone mineral density) scans to Japanese women aged 55 years and over and treating, with risedronate, those that are shown to be osteoporotic. Fracture rates, cost data, utility values, and the increased risks of fractures associated with T-score and vertebral fracture history were taken from published literature. We estimated the cost of fractures avoided due to risedronate treatment, allowing the net changes in cost, incorporating both intervention and fracture costs to be calculated. The QALYs (quality adjusted life years) gained through treatment were calculated enabling cost per QALY ratios to be presented. Further analyses were undertaken assuming treatment was reserved for older women and/or those who had sustained a vertebral fracture in the previous 2 years. Cost per QALY values were inversely related to absolute risk of fracture. Assuming a cost per QALY value threshold of US$100,000, we concluded that providing BMD scans to women aged 70 years and over who had sustained a vertebral fracture in the previous 2 years and treating those that were osteoporotic was cost-effective. However, providing BMD scans for women without a vertebral fracture in the previous 2 years was not cost-effective, even in women aged 85 years and older.