Reference Values, Stability, and Change Rates of Total Femur Bone Mineral Density (BMD) in the United States: National Health and Nutrition Examination Survey (NHANES) 2005-2020

Research Objectives: Bone mineral density (BMD), as measured by dual-energy x-ray absorptiometry, is used as a surrogate marker for fracture risk. This study aimed to: (1) describe the age-related change of total femur BMD across the life span in four distinct cross-sectional surveys by survey year 2005-2020, (2) compare the total femur BMD by age, sex, survey year, race/ethnicity, education, poverty level, and history of ever served on active duty, (3) study the relationships between the total femur BMD and other BMD scans at the femoral (femoral neck, trochanter, intertrochanter, Ward's triangle) and spine regions, and (4) explore the relationships between the grip strength and the total femur BMD.

Design: This is an observational study.

Setting: General community.

Participants: Total femur BMD, taken from 26,228 noninstitutionalized participants, aged 8 to 85, were obtained from the National Health and Nutrition Examination Survey (NHANES) study.

Interventions: N/A

Main Outcome Measures: Dual Energy X-ray Absorptiometry – Femur, Spine.

Results: The mean total femur bone mineral density (BMD) was lower for younger children, gradually increased to reach a plateau in early adult life, peaked around 18-19 years old (BMD = 1.12 gm/cm^2 for males, and 0.99 gm/cm^2 for females), and then gradually declined thereafter. Males exhibited higher total femur BMD than females after puberty. In middle adulthood, the mean total femur BMD in females was 92% of that in males, decreasing to 81% in individuals near 80 years old. Being female, non-Hispanic white, and having an income below the poverty level were associated with lower total femur BMD levels (p < 0.001). From 2005 to 2020, stable trends in total femur BMD were observed (p = 0.994). Although individuals who served on active duty in the US armed forces had a slightly higher mean total femur BMD than those who did not, the difference was not significant (p = 0.173). Total femur BMD showed a very high correlation with BMD scans at the femoral sites (femoral neck, trochanter, intertrochanter, Ward's triangle) with r = 0.89, 0.94, 0.98, and 0.70, respectively. Total femur BMD exhibited a high correlation with BMD scans at the spine (total spine, L1 to L4) with r = 0.75, 0.73, 0.73, 0.70, and 0.69, respectively. However, the correlation between total femur BMD and handgrip strength at the dominant hand was low with r = 0.47.

Conclusions: This study reported the reference values of the BMD . Targeted educational efforts are warranted to enhance knowledge of personal risk indicators.

Author(s) Disclosures: No conflict of interest.