DESIGN OF THE FRACTURE INTERVENTION TRIAL

The Fracture Intervention Trial (FIT) is a randomized, double-masked, placebo-controlled trial designed to test the hypothesis that alendron ate, an amino-bisphosphonate, will reduce the rate of fractures in wom en aged 55-80 years with low hip bone marrow density (<0.68 gm/cm2 at the femoral neck). It is being conducted at 11 clinical centers around the United States with a coordinating center at UC San Francisco. The goal was to randomize 6000 women. When recruitment was completed (in May 1993), 6457 women had been randomized, amounting to 108% of goal. The women were assigned to one of two substudies. The first (Vertebral Deformity study) includes 2023 women who have at least one vertebral deformity, and will test the hypothesis that alendronate reduces the r ate of new vertebral deformities during 3 years of follow-up. This sub study has a power of 0.90 to detect a 32% reduction in the incidence o f new vertebral deformities, assuming a 6.5% annual incidence of new v ertebral deformities in the placebo group. The second study (Clinical Fracture study) includes 4434 women without vertebral deformities at b aseline and will test the hypothesis that alendronate reduces the rate of clinically recognized fractures of all types over an average of 4. 25 years of follow-up. This substudy has a 0.90 power to detect a 25% reduction in the rate of all clinical fractures, assuming 4% annual in cidence in the placebo group. To our knowledge, this is the largest pr ospective, randomized, controlled study undertaken to determine the ef fectiveness of a treatment in reducing the risk of fractures in postme nopausal women.