Drug treatment of osteoporosis, defined by the World Health Organization as bone mineral density greater than 2.5 standard deviations less than the young healthy mean, has been proven to prevent fractures. It is less clear, however, whether physicians should treat osteopenia (femoral-neck T-score of −1.6 to −2.5) in post-menopausal women who do not have a history of fractures. This is because there is a high prevalence of osteopenia in these patients and the drugs are expensive. The National Osteoporosis Foundation and the American College of Obstetrics and Gynecology recommend drug therapy for fracture prevention in women with T-score thresholds of −2.0 or less if no additional fractures are present and −1.6 or less if one or more additional fractures are present. Schousboe and colleagues performed a cost-effectiveness analysis to estimate the cost per quality-adjusted life-year (QALY) gained from a five-year alendronate (Fosamax) regimen in women 55 to 75 years of age with osteopenia and no additional risk factors.
Primary data sources for the analysis were the Fracture Intervention Trial, which evaluated the effectiveness of alendronate versus placebo in women without preexisting vertebral fractures; studies of age-specific fracture rates; acute and long-term medical costs associated with hip and vertebral fractures; estimated costs associated with missed days of work; and calculations of disutility related to each type of fracture. The participants were divided into eight health states based on the presence, location, and presentation (i.e., clinically evident at onset or identified later on incidental radiography) of fractures. The yearly cost of alendronate was set at $842, the average wholesale price in 2001. Other assumptions included a 100 percent adherence rate and trivial medical costs from side effects.
The calculated cost per QALY gained from alendronate treatment ranged from $70,732 for a 65-year-old woman with a nearly osteoporotic T-score of −2.4 to $332,250 for a 75-year-old woman with a nearly normal T-score of −1.5. The cost per QALY increased with age and decreased with more negative T-scores. At a T-score threshold of −1.5, even a 55-year-old woman only benefited from alendronate therapy at a cost of more than $250,000 per QALY.
Citing a commonly used societal cost-effectiveness threshold of $50,000 per QALY gained, the authors conclude that alendronate therapy is not a cost-effective means to prevent fractures in postmenopausal women with osteopenia and no other risk factors.