A cost-effectiveness model of tibolone as treatment for the prevention of osteoporotic fractures in postmenopausal women in Sweden

Background: Osteoporosis is a major cause of morbidity and mortality in the elderly and, in particular, among postmenopausal women. Hormone replacement therapy (HRT) has been shown to protect against fractures, as well as to alleviate climacteric symptoms related to menopause. Unfortunately, HRT has a number of adverse effects and many patients are noncompliant. Tibolone, a synthetic steroid with tissue-specific estrogenic, progestogenic and androgenic effects, has been shown to prevent the loss of bone mass as well as to relieve climacteric symptoms in postmenopausal women, with fewer accompanying adverse effects. Objective: To estimate the economic impact in Sweden of administering tibolone 2.5 mg/day to postmenopausal women at risk for osteoporosis-related bone fractures relative to a policy of no intervention. Design and Setting: Modelling study performed from the national health system perspective in Sweden. Methodology: Disease modelling was used to simulate the risks of osteoporosis-related hip, vertebral and forearm fractures over time in hypothetical cohorts of postmenopausal women. The occurrence of fractures was predicted using risk functions estimated with data from actual cohorts of women in Sweden as well as the USA. Sweden-specific cost data were then used to estimate the economic impact with cost-effectiveness tools. Results: The model predicts that 22% of hip fractures and 13% of combined hip, vertebral and forearm fractures can be avoided over a 25-year time-period by administering tibolone to osteoporotic women. Depending on the severity of loss in bone mass and the values assumed for key parameters, estimates of the cost effectiveness of treatment range from cost saving to incremental costs per quality-adjusted life-year (QALY) gained of around SEK200 000. Delaying treatment to late menopause tends to decrease cost effectiveness. Conclusion: Our findings suggest that, relative to no treatment, tibolone is a cost-effective treatment in Sweden for the prevention of fractures in women with low bone mass,especially when treatment is initiated around the onset of menopause and is administered for 5 years.