Decreasing trend of bone mineral density in US multiethnic population: analysis of continuous NHANES 2005–2014

Y. Xu, Q. Wu

Studies examining recent bone mineral density (BMD) trends in the US population are limited. In our study, we found that age-adjusted mean BMD among US men and women was stable from 2005 to 2010, but then declined in 2013-2014. We also explored factors associated with decreasing BMD in recent years. Osteoporosis prevalence in the USA declined between 1988 and 2006, while the declining trend in hip fracture may have plateaued in 2013-2014. We aimed to examine whether there has been a corresponding change in BMD trajectory for the US population. Continuous National Health and Nutrition Examination Survey (NHANES) data from 2005-2006 to 2013-2014 were analyzed to examine BMD trends among US men and women aged 30 years and older and among different race/ethnicity subgroups. ANOVA and Bonferroni adjustments were used to examine the differences in mean BMD, and multiple linear regressions adjusting for potential confounding effects were employed to examine BMD trends. After age standardization, the mean BMD of the femur neck for the first three NHANES cycles was stable (all p > 0.1) in both men and women, but significantly decreased in 2013-2014, from 0.864 g/cm2 to 0.846 g/cm2 (p = 0.0025) in men and from 0.789 to 0.771 g/cm2 (p = 0.03) in women. The overall mean femur neck BMD in 2013-2014 was significantly lower than that in earlier survey cycles in both men and women, even after adjusting for multiple covariates, including age, race, physical activity, previous fracture, BMI, and other variables. Similar results were observed in subgroup analyses of race and sensitivity analyses. Age-adjusted mean BMD decreased in 2013-2014 in both men and women, and this significant decrease was also observed in sensitivity and subgroup analyses. The decreased BMD in 2013-2014 still remained significant even after being adjusted for multiple potentially confounding effects.