Fracture Risk Assessment without Race/Ethnicity Information

Context: Dual-energy x-ray absorptiometry-derived bone mineral density (BMD) does not explain interracial differences in fracture risk; thus, BMD-based fracture risk assessment requires patient race/ethnicity information and ethnicity-specific BMD reference databases. Objective: The objective of the study was to investigate whether composite femoral neck strength indices, which integrate dual-energy x-ray absorptiometry-derived femoral neck size, femoral neck BMD, and body size, will allow fracture risk assessment without requiring race/ethnicity information. Design: This was a prospective cohort study. Setting and Participants: A total of 1940 community-dwelling women aged 42-53 yr from four race/ethnicity groups (968 Caucasian, 512 African-American, 239 Japanese, and 221 Chinese) were followed up for 9 yr. Outcome Measurements: Self-reported, nondigital, noncraniofacial fractures were measured. Results: Two hundred and two women (10.4%) sustained fractures and 82 (4.3%) had minimum-trauma fractures. Each SD increment in any of the strength indices was associated with a 34-41% reduction in fracture hazard over 9 yr (each P < 0.001). Race/ethnicity predicted fracture hazard independent of BMD(P = 0.02) but did not predict fracture hazard independent of any of the composite indices (P = 0.11-0.22). Addition of race/ethnicity did not improve risk discrimination ability of the strength indices, but did significantly improve the discrimination ability of BMD. The discrimination ability of BMD with race/ethnicity was not statistically different from that of any of the strength indices without race/ethnicity. Conclusions: Composite strength indices of the femoral neck can predict fracture risk without race/ethnicity information as accurately as bone mineral density does in combination with race/ethnicity information and therefore would allow risk prediction in people of mixed race/ethnicity and in groups without a BMD reference database. (J Clin Endocrinol Metab 97: 3593-3602, 2012)