- OBJECTIVE: The aim of this study was to evaluate the cost effectiveness of multi-therapy treatment strategies in the prevention of vertebral fractures in postmenopausal women with osteoporosis. DESIGN: A retrospective, incremental cost-effectiveness analysis was conducted from a societal perspective. It compared 9 treatment strategies over 3 years and incorporated the willingness of patients to initiate and continue each therapy. MAIN OUTCOME MEASURES AND RESULTS: Four nondominated strategies formed the efficient frontier in the following order: (i) calcium-->no therapy; (ii) ovarian hormone therapy (OHT)-->calcium-->no therapy [166 Canadian dollars ($Can)]; (iii) OHT-->etidronate-->calcium-->no therapy ($Can2331); and (iv) OHT-->alendronate-->calcium-->no therapy ($Can40,965). The figures in parentheses are the incremental costs per vertebral fracture averted to move to that strategy from the previous strategy for patients who had undergone a hysterectomy. CONCLUSIONS: We identified 4 efficient multi-therapy strategies for the treatment of vertebral osteoporosis in postmenopausal women, 2 of which were consistent with the practice guidelines of the Osteoporosis Society of Canada. Decision-makers may select from among these efficient strategies on the basis of incremental cost effectiveness.