Endothelial activation and stress index and bone mineral density in a cross-sectional study

ObjectiveReduced Bone Mineral Density (BMD) is influenced by multiple factors, including muscle status, chronic inflammation, and micro-circulatory alterations. Practical indicators derived from routine laboratory tests are needed to facilitate risk identification in real-world settings. This study aimed to investigate the association between the Endothelial Activation and Stress Index (EASIX) and BMD, and to explore the potential utility of this composite index in reflecting bone health status.MethodsThis cross-sectional study was based on the National Health and Nutrition Examination Survey (NHANES) 2011-2018. BMD was measured by dual-energy X-ray absorptiometry (DXA). Weighted multi-variable linear regression models and smooth curve fitting were used to examine linear and nonlinear associations of EASIX with total BMD, trunk BMD, and lumbar BMD. Subgroup analyses and tests for interaction were additionally performed.ResultsA total of 8,101 participants were included. After categorization by EASIX quartiles, higher EASIX quartiles were associated with higher BMD levels in the fully adjusted model. In the highest quartile (Q4), EASIX was positively associated with total BMD (β=0.025, 95% CI: 0.013-0.036), lumbar BMD (β=0.028, 95% CI: 0.008-0.048), and trunk BMD (β=0.027, 95% CI: 0.015-0.040). Subgroup analyses indicated significant interactions of age, smoking status, physical activity, and hypertension status on the association between EASIX and total BMD; physical activity and hypertension status also significantly modified the associations of EASIX with lumbar BMD and trunk BMD (all P for interaction < 0.05).ConclusionThis study reports a complex, nonlinear association between EASIX and BMD. Longitudinal studies are warranted to validate the temporal relationship between EASIX and bone health outcomes.