Nearly one half of postmenopausal women have osteoporosis. Vertebral body fractures represent the single most common osteoporotic fracture, but nonvertebral fractures account for the majority of morbidity, mortality and cost associated with this condition. Alendronate is a potent and specific inhibitor of osteoclastmediated bone resorption and is known to increase bone mineral density in post-menopausal women with osteoporosis. Karpf and associates conducted a meta-analysis to determine what effect alendronate has on the incidence of nonvertebral fracture in women with osteoporosis.
Five trials were included in the study. The bone mineral density of each woman included in the study was measured at the lumbar spine, the trochanter and the femoral neck. Total body bone mineral density was also measured, and all symptomatic fractures were recorded.
Alendronate, 10 mg daily, was discovered to be the optimal dosage leading to increases in bone mineral density at all sites tested. The 5-mg dose of alendronate was approximately 70 percent as effective as the 10-mg dose in producing these increases. The 10-mg dose was the only dosage that did not reach a plateau in its effectiveness over the three-year period studied. Each dose of alendronate tested, however, led to improvements in body mass index when compared with placebo. The rate of nonvertebral fracture per 100 patient-years in the placebo group was 4.45, compared with a rate of 3.26 in the alendronate-treated group. These rates were lower (3.66 and 2.99, respectively) in women younger than age 65, and higher (5.34 and 3.57, respectively) in women older than age 65.
The authors conclude that, in postmenopausal women with osteoporosis, treatment with alendronate leads to increases in body mass index at all sites tested, including the hip and wrist, and decreases the risk of nonvertebral fracture for at least the first three years of treatment.