At what hip fracture risk is it cost-effective to treat?
Intervention thresholds (ITs), the 10-year hip fracture risk at which treatment can be considered to be cost-effective, have previously been estimated for Sweden and the UK. The aim of this study was to provide a Markov cohort model platform for a multinational estimation of thresholds at which intervention becomes cost-effective and to investigate and determine the main factors behind differences in these thresholds between countries. Intervention thresholds were estimated for Australia, Germany, Japan, Sweden, Spain, the UK and USA using a societal perspective. The model was populated with as much relevant country-specific data as possible. Intervention was assumed to be given for 5 years and to decrease the risk of all osteoporotic fractures by 35%. The societal willingness to pay (WTP) for a quality-adjusted life-year (QALY) gained was set to the gross domestic product (GDP) per capita multiplied by two. In the base case analysis, the 10-year hip fracture probability at which intervention became cost-effective varied across ages and countries. For women starting therapy at an age of 70 years, the IT varied from a hip fracture probability of 5.6% in Japan to 14.7% in Spain. The main factors explaining differences in the IT between countries were the WTP for a QALY gained, fracture-related costs and intervention costs. The ITs presented in this paper are appropriate for use in treatment guidelines that consider health economic aspects, and they can be used in combination with fracture risk prediction algorithms to improve the selection of patients who are suitable for osteoporotic intervention.