Mortality following atypical femoral fractures in men

Atypical Femoral Fractures (AFFs) are a very uncommon complication of long-term bisphosphonate (BP) treatment for osteoporosis. Prior studies of mortality following AFFs have shown lower mortality compared to typical hip or shaft fractures but have included few men. The purpose of this report was to determine differences in mortality among men treated with BPs who experienced AFFs, hip fractures, or typical subtrochanteric/femoral shaft (ST/FS) fractures. We included men from the Veterans Affairs Corporate Data Warehouse who filled at least one BP prescription over a nearly twenty-year span (October 1, 1999, through December 31, 2022). ST/FS and hip fractures after a first filled prescription for a BP were identified using ICD-9 and ICD-10 codes. Radiographic review was conducted for ST/FS fractures to determine which were AFFs using the American Society of Bone and Mineral Research (ASBMR) 2014 criterion. Demographic and clinical characteristics and cumulative duration of BP exposure prior to the incident fracture were determined. There were 23 men with an AFF, 4,591 with a hip fracture, and 225 with a (non-AFF) ST/FS fracture. At 12-months post fracture, 4% of men with an AFF had died, compared with 25% of men with a hip fracture and 15% of men with an ST/FS fracture. Over 5 years of follow-up, mortality following fracture differed among the three different fracture groups (χ2 = 6.21, d.f. = 2, p = 0.045) with death occurring in 7 of 23 (30%) men with an AFF, compared to 2,380 of 4,591 (52%) men with a hip fracture and 109 of 225 (48%) men with a ST/FS fracture. In Cox Proportional models, over five years, with and without adjustment for covariates, there were no significant differences in mortality following an AFF compared with a hip fracture or an AFF compared with a ST/FS fracture (p> 0.10 for all). It is possible that mortality is lower following AFF compared with a hip or ST/FS fracture, however limited sample size among those with AFF may have precluded ascertainment of such a difference.