We constructed a Markov cost-utility model that contained 8 health states and compared 5 years of treatment with alendronate (1 of the most commonly prescribed antiresorptive agents) with no drug therapy for women 55 to 75 years of age with varying levels of BMD T-scores (−1.5 to −2.4). The health states we used were no fracture, post-distal forearm fracture, post-clinical vertebral fracture (that is, clinically evident at onset), post-radiographic vertebral fracture (that is, not clinically evident at onset), post-hip fracture, post-other fractures (that is, fracture of the proximal forearm, humerus, scapula, clavicle, sternum, ribs, pelvis, distal femur, patella, tibia, or proximal fibula), post-hip and vertebral fracture, and death. Women in the no fracture state can develop a distal forearm, hip, clinical vertebral, radiographic vertebral, or other fracture, at which time transition to that post-fracture state occurs. We assigned the direct and indirect costs of that fracture as transition costs. We modeled the disutility associated with these fractures as a lower value of a quality-adjusted life-year (QALY) associated with that fracture state. We assigned long-term care costs beyond the first year after hip fracture as a cost per year in the post-hip and vertebral fracture or post-hip fracture state. Individuals are eligible (at risk) to move to a different state once every 6 months. We assumed a discount rate of 3% for both costs and health benefits and a drug adherence rate of 100%. For the base-case analyses, we ran the model with 9 different combinations of starting age (55, 65, and 75 years) and femoral neck T-score (−1.5, −2.0, and −2.4) until age 105 years, using Monte Carlo simulations with 40 000 trials each, by using Data Pro HealthCare software (TreeAge Software, Inc., Williamstown, Massachusetts).