Drug Holidays May Reduce Risk for Atypical Femur Fracture

The following article is part of conference coverage from the 2018 American Society for Bone and Mineral Research in Montreal, Canada. Endocrinology Advisor’s staff will be reporting breaking news associated with research conducted by leading experts on bone health. Check back for the latest news from ASBMR 2018 .

Discontinued use of bisphosphonate can reduce the risk for atypical femur fractures, according to research presented at the 2018 American Society for Bone and Mineral Research Annual Meeting in Montreal, Quebec, Canada.

Annette L. Adams, PhD, and colleagues at Kaiser Permanente Southern California sought to address the relationship of time since last bisphosphonate use and risk for atypical femur fractures, considering that long-term bisphosphonate use has been associated with an increased risk for atypical femur fractures.

The cohort consisted of 152,934 women age ≥50 years, who were a part of the Kaiser Permanente Southern California system during the period of January 1, 2007 through September 30, 2015. Moreover, women who had concomitant use of a bisphosphonate and at least 1 pretreatment bone mineral density total hip scan were included. 

Discontinuation of bisphosphonate treatment should have been >3 months before enrolling in the study. Atypical femur fractures were identified by physicians by reviewing x-ray images for fractures that occurred during the study period with International Classification of Diseases-9th edition diagnosis codes for subtrochanteric or femoral shaft fractures. Multivariable time-varying Cox proportional hazards were used to estimate hazard ratios (HR).

Of the total participants, 185 women had atypical femur fractures. There was a 44% reduction in the risk for atypical femur fractures in the first year after discontinuing bisphosphonate therapy (HR 0.56; 95% Cl, 0.38-0.82). Furthermore, an 80% decrease in risk for atypical femur fractures (HR 0.20; 95% Cl, 0.10-0.37) was evaluated in years 1 to 4 after bisphosphonate discontinuation.  Finally, after >4 years, atypical femur fracture risk was reduced by 78% (HR 0.22; 95% Cl, 0.08-0.59) compared with risk in current bisphosphonate users.

Researchers concluded, “[t]hese results suggest that among women with [bisphosphonate] use of varying duration, discontinuation is associated with substantially decreased risk [for] [atypical femur fractures]. Thus, these results suggest that a drug holiday of 3-5 years would likely markedly reduce [atypical femur fractures] risk among long-term [bisphosphonate] users.”

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Reference

Adams AL, Li BH, Ryan DS, Geiger EJ, Dell RM, Black DM. Do drug holidays reduce atypical femur fracture risk?: Results from the Southern California Osteoporosis Cohort Study (SOCS). Presented at: 2018 American Society for Bone and Mineral Research Annual Meeting; September 28-October 1, 2018; Montreal, Quebec, Canada. Abstract 1005.