Bone Material Strength Index: Differences by Race/Ethnicity in Caribbean Hispanic, non-Hispanic White and non-Hispanic Black Older US Adults

Racial differences in fracture risk are not fully explained by differences in areal bone density (aBMD) as measured by dual energy x-ray absorptiometry (DXA). Other aspects of bone quality, such as bone material properties, are not captured by DXA, but may contribute to fracture risk. Few studies have investigated racial/ethnic differences in bone material properties, and none have included Hispanic Americans. We assessed differences in bone material strength index (BMSi) measured by impact micro indentation (IMI) by race/ethnicity. Caribbean Hispanic (CH), Non-Hispanic Black (NHB), and Non-Hispanic White (NHW) participants from the Washington Heights Inwood Community Aging Project (N=148), a population-based study of aging in New York City, were included. While there were racial differences in aBMD, BMSi did not differ by race/ethnicity (CH vs NHB vs NHW: 79.3±6.3 vs. 78.3±15 vs. 77.7±5.2) before (p=0.22) or after (p=0.47) adjustment for age, sex, BMI, fracture status, diabetes, alcohol consumption, smoking, and osteoporosis treatment. There was no significant interaction between race and diabetes status in relation to BMSi. Stratifying by sex, results were similar. In summary, BMSi was similar among CH, NHB, and NHW participants, suggesting that differences in bone material strength, as captured by BMSi, do not account for established racial/ethnic differences in fracture risk in these groups.