Navajo Bone Health Study

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DESCRIPTION (provided by applicant): The Navajo Bone Health Study aims to begin surveillance of bone health on the Navajo Nation. These efforts will in time enable the Navajo Nation to plan screening and culturally appropriate education and intervention programs targeted towards the segments of the population who are at greatest risk for fracture or osteoporosis. Specifically, we hypothesize that bone density (total bone mineral density (BMD), and BMD at the hip and lumbar spine) will be different in Navajo American Indians than Caucasians. We will examine this hypothesis by measuring bone mineral density (BMD) using dual energy x-ray absorptiometry (DXA) and heel ultrasound (broadband ultrasound attenuation (BUA) and speed of sound (SOS) as well as stiffness index (SI)) compare distributions and z-scores with those reported for Caucasians in the NHANES III database by age and gender groups. We aim to validate the use of heel ultrasound for bone health screening in Navajo Native Americans and create clinically relevant cutoffs for referral in this population. We will examine the association of reported adult fractures with BMD measures (DXA and BUA) to relate these measures to a relevant public health outcomes. In addition we will examine the association of body size, diet (nutrients relevant to bone formation including calcium, vitamin D, Vitamin A and protein), and lifestyle (physical activity) factors to and BMD in Navajo adults and children over the age of 18. Data will be collected in a cross-sectional design coincident with the Navajo EARTH cohort study. DXA will be measured in 1296 randomly selected Navajo men and women. We will select 112 men and 112 women in four 10 year age groups (30-39,40-49,50-59, and 60 and older) to assure that we can adequately estimate BMD in each of these gender specific age groups separately. Heel ultrasound will be measured in approximately 2500 Navajo men and women and associations with BMD measured using DXA, reported adult fractures, and diet and lifestyle factors will be explored. This study is an important first step in surveillance of bone health of Navajo American Indians and make efficient use of the Navajo EARTH Cohort Study which is currently in the field.