The association of bone density and hip fracture risk among Asian women.

UNLABELLED: Asian women have lower bone density than White women, but their hip fracture risk similarly increased two-fold or more for each unit decline in bone density T-score. Adjusting for age, T-score, and treatment, hip fracture risk remained lower for Asian compared to White women, with some attenuation after stature adjustment.

BACKGROUND

Few studies have examined the relationship of bone mineral density (BMD) and hip fracture risk among US Asian women.

METHODS

Incident hip fractures were examined among Asian/Pacific Islander (PI) and non-Hispanic White (NHW) women aged 60-89 years who had femoral neck-(FN)-BMD measured in 2000-2019 without prior osteoporosis treatment. The BMD-T-score risk gradient for hip fracture was examined using Cox proportional hazard models, adjusting for age and time-updated osteoporosis therapy. Hip fracture risk for Asian versus NHW women was also examined (overall and by low T-score category), adjusting for age, T-score, and osteoporosis therapy.

RESULTS

Among 54,294 Asian/PI and 219,585 NHW women, 14.3% of NHW and 23.5% of Asian/PI women had FN-T-score ≤ -2.5 (osteoporosis) that ranged 12.6% (Native Hawaiian/PI), 17.4% (South Asian), 22-23% (Chinese, Filipina, Korean), 26.7% (Japanese), and 30.5% (Vietnamese). During five-year follow-up, hip fracture incidence was 1.03 (Asian/PI) and 3.39 (NHW) per 1000 person-years. Each unit T-score reduction was associated with adjusted hazards ratio (aHR) for hip fracture of 2.11 [2.03-2.20] NHW, 2.84 [2.11-3.82] Chinese, 2.69 [2.01-3.60] Japanese, 2.22 [1.67-2.97] Filipina, and 2.18 [1.19-3.99] South Asian. Comparing Asian to NHW women, aHRs for hip fracture were 0.2-0.3 (Chinese, Filipina) and 0.4-0.6 (Japanese, South Asian), with some attenuation after height adjustment.

CONCLUSION

Among Asian and NHW women, each unit reduction in FN-T-score was associated with ≥ two-fold higher risk of hip fracture that varied by ethnicity. Accounting for T-score differences, Asian women had lower hip fracture risk than NHW women. These findings have implications for fracture risk assessment in these populations.