Factors Affecting Discontinuation of Alendronate Treatment in Postmenopausal Japanese Women With Osteoporosis

Background: The main challenge to the long-term treatment of osteoporosis with bisphosphonates has been patient adherence. The purposes of this cohort study were to investigate the 3-year outcome of alendronate treatment in post-menopausal Japanese women with osteoporosis and to identify factors that contributed to the discontinuation of alendronate treatment. Methods: A total of 72 postmenopausal Japanese women with osteoporosis and aged from 58 to 85 years were treated with alendronate in a 3-year trial. Metacarpal bone mineral density, serum alkaline phosphatase, and urinary cross-linked N-terminal telopeptides of type I collagen were monitored, and factors contributing to the discontinuation of alendronate treatment were determined. Results: Fourteen patients dropped out of the trial. The reasons for dropout were side effects (diarrhea [n = 1], gastric symptoms [n = 9], and inflammation of the mouth [n = 1]) or non-compliance (n = 3). Logistic regression analysis showed that the number of prevalent vertebral fractures was a significant factor affecting the discontinuation of alendronate treatment for the reasons listed above. In 58 patients who continued the 3-year treatment, urinary cross-linked N-terminal telopeptides of type I collagen level was reduced by 44.1% at 3 months and serum alkaline phosphatase level was decreased by 11.6%, 11.8%, and 12.5% at 1, 2, and 3 years, respectively. However, metacarpal bone mineral density did not change significantly. Conclusion: Alendronate treatment decreased urinary cross-linked N-terminal telopeptides of type I collagen and serum alkaline phosphatase levels, and maintained metacarpal bone mineral density in postmenopausal Japanese women with osteoporosis. The patients adhered well to alendronate treatment in our clinic. The number of prevalent vertebral fractures was an important factor affecting the discontinuation of alendronate treatment due to side effects and non-compliance.