Fracture Prevention with Infrequent Zoledronate in Women 50 to 60 Years of Age

Zoledronate prevents fractures in older women when administered every 12 to 18 months, but its effects on bone density and bone turnover persist beyond 5 years. Whether infrequent zoledronate administration would prevent vertebral fractures in early postmenopausal women is unknown.

We conducted a 10-year, prospective, double-blind, randomized, placebo-controlled trial involving early postmenopausal women (50 to 60 years of age) with bone mineral density T scores lower than 0 and higher than -2.5 (scores of -1 or higher typically indicate normal bone mineral density) at the lumbar spine, femoral neck, or hip. Participants were randomly assigned to receive an infusion of zoledronate at a dose of 5 mg at baseline and at 5 years (zoledronate-zoledronate group), zoledronate at a dose of 5 mg at baseline and placebo at 5 years (zoledronate-placebo group), or placebo at both baseline and 5 years (placebo-placebo group). Spinal radiographs were obtained at baseline, 5 years, and 10 years. The primary end point was morphometric vertebral fracture, which was assessed semiquantitatively and defined as at least a 20% change in vertebral height from that seen on the baseline radiograph. Secondary end points were fragility fracture, any fracture, and major osteoporotic fracture.