White Blood Cell to HDL ‐C Ratio and Sarcopenia: A Dual‐Cohort Analysis Including Exploratory Insights on Hepatitis B History

Abstract

ABSTRACT Background Sarcopenia, driven by inflammation and lipid dysregulation, lacks inexpensive screening tools. The white blood cell to HDL‐C ratio (WHR) integrates these pathways, but its utility for sarcopenia screening remains unvalidated. Objective This study evaluated the WHR‐sarcopenia association in dual cohorts, validated it using machine learning, and explored potential effect modification of hepatitis B virus (HBV) status. Methods We analyzed 10 131 NHANES (2011–2018) and 7872 KNHANES (2010–2011) adults. Sarcopenia was defined via DXA using FNIH/AWGS criteria. Weighted logistic regression, restricted cubic splines, and machine learning (LASSO, XGBoost) were applied. Results Higher ln(WHR) was independently associated with sarcopenia in NHANES (adjusted OR = 2.50; 95% CI: 2.01–3.10) and consistently validated in KNHANES (OR = 1.85; 95% CI: 1.49–2.29). WHR ranked among the top predictive features across machine learning models. Exploratory stratified analysis suggests that the association between ln(WHR) and sarcopenia appears to be stronger in the HBV‐exposed subgroup. However, although the formal interaction test was not significant ( p = 0.270), these findings are hypothesis‐generating results. Conclusion WHR, a cost‐free routine metric, is robustly linked to sarcopenia. Integrating it into geriatric assessments could facilitate early high‐risk identification for timely interventions, while exploratory findings suggesting a possible modifying role of HBV history require prospective validation.