Skeletal Health Outcomes among US Asian Women - PROJECT SUMMARY/ABSTRACT Both ethnic diversity and the burden of osteoporosis have increased with the aging US population. Asians now comprise 7% of the US and 17% of California’s population, the state in which nearly one third of all US Asians reside. In 2002, the US Preventive Services Task Force updated recommendations for osteoporosis screening to all women age 65 years and older. Because Asians have lower bone density than whites, they have a greater likelihood of being diagnosed with osteoporosis on the basis of their bone density screening test results, yet they have a lower risk of hip fracture. Existing fracture risk calculators consider race/ethnicity in estimating fracture risk, but the inherent assumptions remain largely untested. The most widely used calculator is FRAX, which provides 10-year risk estimates of hip and any one of four major osteoporotic fractures for white, black, Hispanic, and Asian race. For US Asians, an adjustment factor (0.5 for women) is applied during fracture risk calculation, based on epidemiologic studies indicating that US Asian women have a 40-50% lower incidence of hip fracture than white women. However, data for fractures other than hip are limited for Asians, and population fracture data by Asian ethnic subgroups are largely lacking. US Asians comprise a heterogeneous population whose ancestry originates primarily from East, South, and Southeast Asia; in California, the two largest subgroups are Filipino and Chinese. It is notable that using the same age, gender, bone density, and clinical profile, FRAX calculators produce different results for US Asian versus Asians in Hong Kong and Taiwan (both higher), China (similar), and the Philippines (lower). These differences could stem from differences in fracture epidemiology in these countries. A more precise understanding of fracture risk in US Asians is paramount for tailoring their fracture prevention counseling and care. Using data from Kaiser Permanente Northern California, a large integrated healthcare delivery system with membership across Northern California and especially in the San Francisco Bay Area and Sacramento regions (where large numbers of Asians reside), this proposed study will conduct the first large-scale assessment of bone density and fracture outcomes among US Asians and Asian ethnic minorities. Our three primary aims are: (1) to compare the incidence of hip and major osteoporotic fractures for white and Asian men and women and by Asian ethnic minorities; (2) to characterize the association between bone density and fracture risk for Asian women in relation to findings observed for white women; and (3) to examine the predictive accuracy of fracture risk tools for Asian women and to determine whether replacement of existing base population fracture data with Asian-specific fracture data yields more accurate fracture risk prediction for Asians. Findings from this study will provide a more accurate way to calculate fracture risk in US Asians and, in the future, could enable millions of Asian Americans to obtain fracture risk data tailored to their ethnic profile.
