NEW YORK - Long-term use of the bisphosphonate alendronate substantially lowers the risk of hip fracture without increasing the risk of atypical fractures of the subtrochanteric femur or femoral shaft, according to a Danish study.
"These findings support an acceptable balance between benefit and risk with treatment with alendronate in terms of fracture outcomes, even for over 10 years of continuous use," the authors conclude in the BMJ online June 28.
Placebo-controlled trials have shown a reduction in hip fracture risk with alendronate treatment for three years in older women with osteoporosis, but observational studies have suggested that atypical femur fractures are more common in long-term users of bisphosphonates.
To investigate further, researchers analyzed data from Danish practice registries on nearly 62,000 alendronate users. A total of 1,428 people sustained a fracture of the subtrochanteric femur or femoral shaft (ST/FS), an incidence rate of 3.4 per 1,000 person years, and 6,784 sustained a hip fracture (incidence rate 16.2 per 1,000 person years).
"Long-term adherent use of alendronate in excess of 10 dose years was associated with an adjusted 30% lower risk of hip fracture and no increase in the risk of fractures of the subtrochanteric femur or femoral shaft," the investigators report in their paper.
"In addition, we have shown that even in the worst case scenario (assuming 100% of subtrochanteric and femoral shaft fractures are atypical and secondary to bisphosphonate use and making no allowance for the higher prevalence of comorbid conditions in these patients) the number of atypical femur fractures remains too low to offset the benefits on hip fracture in patients with long-term alendronate use up to 10 years," they say.
"Safety concerns have probably limited the adherence to anti-osteoporosis therapies," Dr. Daniel Preto-Alhambra, University of Oxford, Nuffield Orthopaedics Centre in the United Kingdom, who worked on the study, told Reuters Health by email.
"Our findings support a good risk-benefit for this treatment in terms of femur fracture risk reduction, even when prescribed for 10 years and over. These data should reassure physicians and patients on the bone-related risk-benefits of alendronate therapy," he added.
The study had no commercial funding. Several authors made disclosure statements.