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

Abstract

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.

Keywords: Asian; Bone density; Fracture risk; Hip fracture; Osteoporosis.