Femur Fractures Very Rare With Bisphosphonates

Risk of subtrochanteric or diaphyseal femur fracture low, even with long-term drug use

WEDNESDAY, March 24 (HealthDay News) -- The occurrence of subtrochanteric or diaphyseal femur fractures is very rare in women who have used bisphosphonates, even for as long as 10 years, according to an article published online March 24 in the New England Journal of Medicine.

Dennis M. Black, Ph.D., of the University of California in San Francisco, and colleagues performed secondary analyses using the findings from three large randomized trials evaluating bisphosphonates: the Fracture Intervention Trial (FIT), the FIT Long-Term Extension (FLEX) trial, and the Health Outcomes and Reduced Incidence with Zoledronic Acid Once Yearly (HORIZON) Pivotal Fracture Trial (PFT). The researchers reviewed 284 records for hip and femur fractures among 14,195 women in the trials.

The researchers identified 12 fractures in 10 women classified as subtrochanteric or diaphyseal femur fractures. Compared to placebo, they found that the relative hazard ratios were 1.03 for alendronate use in the FIT trial, 1.33 for continued alendronate use in the FLEX trial, and 1.50 for zoledronic acid use in the HORIZON-PFT trial. Even though increases in risk were not significant, confidence intervals were broad.

"The results provide assurance that subtrochanteric fractures are extremely rare, as compared with femoral-neck and intertrochanteric fractures," writes the author of an accompanying editorial. "The findings also suggest that many more common and equally devastating hip fractures are prevented by bisphosphonates than are potentially caused by the drugs."

The study was funded by Merck and Novartis. Several authors, including the author of the editorial, received grant support, consulting and lectures fees, or travel reimbursement from Merck, Novartis and other pharmaceutical companies.

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