Lipid Indicators and Low Bone Mass Among Taiwanese Adults: A Cross-Sectional Association Study

Background & Aims: This study investigated the associations of lipid indicators, particularly the total cholesterol to high-density lipoprotein cholesterol ratio (TC/HDL-C), with low bone mass in adults. Methods: This cross-sectional study included 6389 participants aged ≥19 years from the Nutrition and Health Survey in Taiwan (2013-2020). Two study-defined low-bone-mass phenotypes were evaluated as research phenotypes rather than densitometric diagnoses: central-site low bone mass, defined as a T-score < -1.0 at either the lumbar spine (L1-L4) or the lower of the bilateral femoral neck T-scores, and total-body low bone mass, defined as a total-body T-score < -1.0. Multivariable logistic regression models and restricted cubic spline analysis were performed to examine associations of lipid indicators with low bone mass. Subgroup analyses by sex, age, and age-defined menopausal status were exploratory. Results: Among 6389 participants, 1069 had total-body low bone mass. Total-body low bone mass showed more evident associations with lipid-related markers than central-site low bone mass. Each 10 mg/dL increase in HDL-C was associated with higher odds of total-body low bone mass (adjusted odds ratio [OR] = 1.080, 95% confidence interval [CI]: 1.018-1.147, p = 0.011). Although the linear association between TC/HDL-C and low bone mass was not statistically significant, spline analysis revealed a significant nonlinear association with total-body low bone mass, with a turning point at 4.39 (p for nonlinearity = 0.016). Exploratory analyses suggested effect modification by age and age-based grouping. Conclusions: Total-body low bone mass showed more evident associations with lipid indicators than central-site low bone mass. HDL-C was linearly associated with low bone mass, whereas TC/HDL-C showed an exploratory nonlinear association, supporting its potential role as a readily available metabolic correlate of skeletal status.