Bone mineral density comparison of total body, lumbar and thoracic: an exploratory study.

OBJECTIVE To analyse the behaviour of bone mineral density (BMD) of total body, lumbar and thoracic spine, and compare it between different age-groups, ethnicity and gender as a secondary analysis of already published data of NHANES. METHODS The study was done and compared data of the National Health and Nutrition Examination Survey which was done from 1999 to 2006. It comprised bone mineral density data of 26,215 subjects of age 8 years and over. The sample was divided into 10 age groups, 3 ethnicities and gender groups. All subjects had bodyweights not exceeding 300lb, and height not greater than 6'5''. Female subjects were non-pregnant. SPSS 16 was used for statistical analysis. RESULTS Of the total subjects, 7712 (29.41%) were Mexican Americans, 11236 (42.86%) were non-Hispanic whites and 7267 (27.73%) were non-Hispanic blacks. There were 13291 (50.69%) males, and each ethnic group also had approximately 50% males. The bone mineral density of non-Hispanic blacks was higher than the other two groups, whereas males of all ethnic groups and races had higher density then females of the same group. Bone mineral density of total body, lumbar and thoracic was significantly different. After 50 years of age, total body, lumbar and thoracic bone mineral density decreased in females but lumbar slightly increased in males, whereas thoracic remained stable and total body decreased. CONCLUSIONS The bone mineral density of male and blacks was higher than female and non-black races in total body, lumbar and thoracic spine. The thoracic BMD was lower and might predict early fracture risk.