Similar Proportions of Women Lose Bone Mineral Density With Raloxifene or Alendronate Treatment

The ISCD recommends that bone mineral density (BMD) be monitored in patients undergoing antiresorptive therapy to identify patients with a significant BMD loss. This analysis compares the proportions of postmenopausal women treated with raloxifene 60 mg/d (n=82) or alendronate 10 mg/d (n=83) who had significant BMD loss in a randomized, double-blind, placebo-controlled trial that assessed changes in lumbar spine and femoral neck BMD from baseline to 1 yr, measured using dual-energy X-ray absorptiometry. According to ISCD criteria, significant BMD loss was defined as greater than the least significant change, calculated as precision multiplied by 2.77 (95% confidence interval). Assuming a 1% precision at the lumbar spine, the proportions of women with a loss of BMD greater than the least significant change (3%) were similar (p>0.05) between the raloxifene (3%) and alendronate (2%) groups. Assuming 2% precision at the femoral neck, the proportions of women with a loss greater than the least significant change (6%) were similar (p>0.05) between the raloxifene (1%) and alendronate (2%) groups. In conclusion, similar proportions of women did not respond to raloxifene or alendronate therapy, as measured by changes in lumbar spine or femoral neck BMD, when precision error was taken into account.