Methods: We developed a Monte Carlo microsimulation to evaluate the cost-effectiveness of five years of alendronate therapy compared to usual care (vitamin D/calcium) in a hypothetical population of treatment-na´ve post-menopausal Caucasian women with severe osteoporosis (T-score, -2.5), osteoporosis (T-score -2.5), and osteopenia (T-score -2.0). We evaluated the cost-effectiveness of alendronate at 100%, 80%, 60%, 40%, and 20% of its 2003 U.S. average wholesale price (AWP, $894). We employed a lifetime horizon and used data from the Study of Osteoporotic Fractures and studies evaluating the efficacy of alendronate in women with low bone density. The main outcome measure was cost per quality-adjusted life-year (QALY).
Results: The incremental cost-effectiveness ratio of alendronate therapy compared to usual care in a 65-year old woman with severe osteoporosis, osteoporosis, and osteopenia is $17,700, $47,000, and $126,100 per QALY, respectively. With a 40% price reduction in its AWP, alendronate therapy costs $72,200 per QALY compared to usual care in osteopenic women; with a 60% price reduction, this cost drops to $45,400 per QALY. Alendronate is cost-saving compared to usual care at approximately 60% of its AWP in women with severe osteoporosis, and 20% of its AWP in women with osteoporosis.
Conclusions: Expected price reductions from loss of patent protection will improve the cost-effectiveness of alendronate therapy and may make it cost-saving in women with severe osteoporosis and osteoporosis. Whether generic alendronate becomes a cost-effective therapy in osteopenic women will depend on the extent of future price reductions.