Secular Trends in Peak Bone Mineral Density: The National Health and Nutrition Examination Survey 1999-2018.

Peak bone mineral density (BMD) is one of the most important factors influencing the development of osteoporosis. It was predicted that a 10% increase in peak BMD will delay the onset of osteoporosis by 13 years. However, changes in peak BMD over time are unknown. This study aimed to investigate secular trends in peak BMD among young adults in the United States. Based on the National Health and Nutrition Examination Survey from 1999-2018, 3,975 males aged 19-28 years and 2370 females aged 31-40 years were our target population for estimating peak lumbar spine BMD. BMD was measured by dual-energy X-ray absorptiometry. Generalized linear models adjusted for multiple covariates were used to examine the secular trends in peak BMD in males and females, respectively. Secular trends for peak lumbar spine BMD from 1999-2000 to 2017-2018 were not statistically significant in males or females (all P_linear and P_quadratic > 0.05). Similar results were observed in race/ethnicity subgroups (all P_linear and P_quadratic > 0.05). However, in stratified analyses by obesity category, peak lumbar spine BMD in obese males and females increased from 1999-2000 to 2009-2010 and then decreased until 2017-2018, while peak lumbar spine BMD in non-obese females decreased from 1999-2000 to 2005-2006 and then increased until 2017-2018 (all P_quadratic < 0.05). Peak lumbar spine BMD was greater in obese males and females than in non-obese males and females up to 2009-2010, but not from 2011-2012 onwards. Overall, there were no significant secular trends in peak lumbar spine BMD. However, secular trends differed between obese and non-obese groups.