Are Race and Sex Associated With the Occurrence of Atypical Femoral Fractures?

Prior studies have suggested that Asian patients and women may be more likely to sustain atypical femoral fractures in association with bisphosphonate use. However, they do not account for confounders such as asymptomatic patients who are long-term bisphosphonate users or patients sustaining osteoporotic fractures. The purpose of this study was to determine the differences in sex and racial association with atypical femoral fractures by comparing demographic characteristics of patients who sustained an atypical bisphosphonate-associated fracture with patients on long-term bisphosphonates without fractures and with patients who sustained osteoporotic fractures. Three groups from prospective registries were identified: (1) patients with atypical femur fractures associated with long-term bisphosphonate use (BFF) (n = 54); (2) patients on long-term bisphosphonates but with no associated fractures (BNF) (n = 119); and (3) patients with osteoporotic proximal femur fractures not associated with bisphosphonates (PFF) (n = 216). Age, sex, and self-reported race/ethnicity were documented and compared. Multivariate and univariate analyses were done as well as age- and sex-stratified analyses. Age and sex distributions of the BFF and BNF patients were similar. There was a higher percentage of Asian patients in the BFF group (17%) than in the BNF group (3%; p = 0.004) as well as Hispanics (13% versus 3% in BNF; p = 0.011). Patients in the BFF group were younger than those in the PFF group (67.5 versus 78.4 years; p < 0.001) and had fewer males (7% versus 14%; p < 0.001). These data suggest that Asians are at higher risk for atypical bisphosphonate-associated fractures. We recommend closer followup in Asian patients who are taking bisphosphonates. Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.