Association between relative fat mass and lumbar bone mineral density in US adults: a cross-sectional study of the National Health and Nutrition Examination Survey 2011–2018

Zhang, Yongxin1,#; Huang, Lei2,#; Li, Mangui3; Yang, Peng4; Cheng, Liming3; Yang, Huilin4; Lu, Shunyi4,*; Zhang, Jian1,*

1Department of Orthopedics, Zhongshan Hospital, Fudan University, Shanghai, China

2Division of Spine, Department of Orthopedics, Tongji Hospital, Tongji University School of Medicine, Shanghai, China

3Department of Inspection Section, Qinghai Red Cross Hospital, Xining, Qinghai Province, China

4Department of Orthopedic Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China

*Correspondence to: Shunyi Lu, lushunyi@suda.edu.cn; Jian Zhang, zhang.jian@zs-hospital.sh.cn.

#Both authors contributed equally to this work and share first authorship.

Abstract

The relationship between obesity and bone health remains controversial, with extensive studies suggesting associations; however, the precise nature of this relationship remains uncertain. Relative fat mass (RFM) is an innovative obesity metric that provides a more precise evaluation of body fat distribution than conventional methods, but its implications for skeletal health remain unexplored. This study aimed to explore the relationship between RFM and lumbar bone mineral density (BMD) in adults from 2011–2018. Weighted multivariate logistic regression, subgroup analysis, and interaction tests were employed to examine the relationship between RFM and lumbar BMD, utilizing data derived from the 2011–2018 National Health and Nutrition Examination Survey. This study included a total of 11,410 participants. Weighted multiple linear regression analysis revealed a significant negative correlation between RFM and lumbar BMD among adults aged 20–59 years. This negative correlation persisted even when RFM was analyzed by quartiles, with individuals in the highest RFM quartile exhibiting lumbar BMD levels 0.046 g/cm2 lower than those in the lowest quartile. However, the results of the subgroup analysis suggested that this negative association was abolished in individuals with diabetes, hypertension, or chronic kidney disease but was not significantly influenced by factors such as sex and race. Our findings indicate a significant negative correlation between RFM and lumbar BMD in US adults aged 20–59 years, with notable attenuation in specific clinical populations, offering fresh perspectives and research targets for clinical analysis.

美国成年人相对脂肪量与腰椎骨密度的关系：2011-2018 年全国健康与营养调查横断面研究

摘要

肥胖与骨骼健康之间的关系仍存在争议，大量研究表明两者之间存在关联，但这种关系的确切性质仍不确定。相对脂肪量是一种创新的肥胖指标，与传统方法相比，它能更精确地评估体脂分布，但其对骨骼健康的影响仍有待探索。此研究旨在探讨2011-2018年成人相对脂肪量与腰椎骨密度之间的关系。研究利用 2011-2018 年美国国家健康与营养调查（NHANES）的数据，采用加权多变量逻辑回归、亚组分析和交互检验来研究相对脂肪量与腰椎骨密度之间的关系。这项研究共纳入了11,410 名参与者。加权多元线性回归分析显示，在20-59岁的成年人中，相对脂肪量与腰椎骨密度之间存在显著的负相关。即使按四分位数对相对脂肪量进行分析，这种负相关关系依然存在，相对脂肪量最高四分位数的参与者腰椎骨密度水平比最低四分位数者低 0.046 g/cm2。然而，亚组分析结果表明，这种负相关在糖尿病、高血压或慢性肾病患者中未见，而性别和种族等因素对其影响不大。这些结果表明，在 20-59 岁的美国成年人中，相对脂肪量与腰椎骨密度之间存在明显的负相关，在特定临床人群中明显减弱，这为临床分析提供了新的视角和研究目标。