Correlates of bone mineral density among postmenopausal women of African Caribbean ancestry: Tobago women's health study

Abstract

Population dynamics predict a drastic growth in the number of older minority women, and resultant increases in the number of fractures. Low bone mineral density (BMD) is an important risk factor for fracture. Many studies have identified the lifestyle and health-related factors that correlate with BMD in Whites. Few studies have focused on non-Whites. The objective of the current analyses is to examine the lifestyle, anthropometric and health-related factors that are correlated with BMD in a population based cohort of Caribbean women of West African ancestry. We enrolled 340 postmenopausal women residing on the Caribbean Island of Tobago. Participants completed a questionnaire and had anthropometric measures taken. Hip BMD was measured by DXA. We estimated volumetric BMD by calculating bone mineral apparent density (BMAD). BMD was >10% and >25% higher across all age groups in Tobagonian women compared to US non-Hispanic Black and White women, respectively. In multiple linear regression models, 35-36% of the variability in femoral neck and total hip BMD respectively was predicted. Each 16-kg (one standard deviation (SD)) increase in weight was associated with 5% higher BMD; and weight explained over 10% of the variability of BMD. Each 8-year (1 SD) increase in age was associated with 5% lower BMD. Current use of both thiazide diuretics and oral hypoglycemic medication were associated with 4-5% higher BMD. For femoral neck BMAD, 26% of the variability was explained by a multiple linear regression model. Current statin use was associated with 5% higher BMAD and a history of breast feeding or coronary heart disease was associated with 1-1.5% of higher BMAD. In conclusion, African Caribbean women have the highest BMD on a population level reported to date for women. This may reflect low European admixture. Correlates of BMD among Caribbean women of West African ancestry were similar to those reported for U.S. Black and White women.

Figure 1

Mean total hip BMD (g/cm²) for Tobagonian women (TWHS, 2002) compared to non-Hispanic Black and non-Hispanic White women, NHANES III, U.S. 1988–1994. Looker, AC et al. Updated data on proximal femur bone mineral levels of US adults 1998; 8:468–489. Osteoporos Int.