Volumetric bone mineral density at the spine and hip in Chinese American and White women

Abstract

This study evaluated racial differences in bone size and volumetric density at the spine and hip in pre- and postmenopausal Chinese American and White women. Compared with White women, Chinese American women have greater cortical volumetric bone density (vBMD) at the hip, congruent with the results at the peripheral skeleton.

Introduction: Chinese American women have lower rates of fracture than White women despite lower areal bone density. At the forearm and tibia, however, Chinese American women have higher cortical vBMD as well as greater trabecular and cortical thickness, but smaller bone area as measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) compared with White women. Since HR-pQCT data are obtained at peripheral sites, it is unclear whether these differences are relevant to the clinically important lumbar spine and hip. This study assesses racial differences in bone size and vBMD at the spine and hip in Chinese American and White women.

Methods: QCT of the spine and hip was measured to assess racial differences in bone size, structure, and vBMD in pre- (n = 83) and postmenopausal (n = 50) Chinese American and White women. Data were adjusted for weight, height, physical activity, total calcium intake, parathyroid hormone, and 25-hydroxyvitamin D levels.

Results: Among premenopausal women, lumbar spine trabecular vBMD was 5.8% greater in Chinese American versus White women (p = 0.01). At the hip, cortical vBMD was 3% greater at the femoral neck (p = 0.05) and 3.6% greater at the total hip (p = 0.01) in premenopausal Chinese American compared with White women. Among postmenopausal women, there was no difference in lumbar spine trabecular vBMD. Cortical vBMD was 4% greater at the total hip (p = 0.02) and tended to be greater at the femoral neck (p = 0.058) in Chinese American versus White women.

Conclusions: Consistent with earlier findings in the peripheral skeleton, cortical vBMD is greater at the hip in Chinese American versus White women.

Fig. 1

Comparison of unadjusted percentage difference in QCT measurements between Chinese American and White premenopausal (a) and postmenopausal (b) women at the lumbar spine (black), femoral neck (gray), and total hip (white). *p≤0.05 before adjustment for covariates; #p≤0.05 after adjustment for weight, height, physical activity, calcium intake, serum parathyroid hormone, and 25-hydroxyvitamin D levels. CSA cross-sectional area; INT integral; vBMD volumetric bone density; Tb trabecular; Ct cortical; C/I the ratio of tissue volume in Ct regions to total tissue volume within the periosteal boundaries, an estimate of Ct thickness