Reference Values, Stability, and Declining Rates of Total Spine Bone Mineral Density (BMD) in the United States

Research Objectives: Bone mineral density (BMD) (gm/cm2), as measured by dual-energy x-ray absorptiometry (DXA), is used as a surrogate marker for fracture risk. This study aimed to: (1) describe the age-related change of total spine BMD across the life span in four distinct cross-sectional surveys by survey year 2005-2020, (2) compare the total spine BMD by age, sex, survey year, race/ethnicity, education, poverty ratio, and history of ever served on active duty, and (3) study the relationships between the total spine BMD and other BMD scans at the femoral and other spine regions (L1 to L4).

Design: This is an observational study.

Setting: General community.

Participants: Total spine BMD, taken from 21,570 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 - Spine.

Results: The total spine BMD varied by sex, survey year, race/ethnicity, education, poverty level, and history of ever served on active duty (p < 0.001). In males, total spine BMD showed annual growth from ages 8 to 17 (from 0.58 to 1.0 gm/cm2), stabilizing thereafter into middle and late adulthood. For females, total spine BMD increased until around 18 years old (from 0.59 to 1.0 gm/cm2), maintained stability from 18 to 47 years old, and then gradually declined as age increases. At the age of 80, the total spine BMD was about 0.91 gm/cm2.Although the survey year showed statistical significance, no practical differences were observed between the ages of 8 and 70. In general, Non-Hispanic Blacks demonstrated higher total spine BMD compared to Non-Hispanic Whites, while Mexican Americans tended to exhibit lower BMD levels in comparison to other groups. Overall, individuals with a background of some college education or an Associate's degree tended to display elevated levels of total spine bone mineral density (BMD), while individuals with an educational attainment of less than the 11th grade typically exhibited the lowest total spine BMD levels. Adults with incomes equal to or above the poverty level exhibited higher total spine BMD compared to those with incomes below the poverty level. The correlations between the total spine BMD and the L1 to L4 and total femur BMD were 0.958, 0.982, 0.984, 0.968, and 0.746, respectively.

Conclusions: This study reported the reference values of the total spine BMD among noninstitutionalized residents in the US. Targeted educational efforts are warranted to enhance knowledge of personal risk indicators.

Author(s) Disclosures: The authors declare no conflict of interest.