Cardiometabolic index as a predictor of sarcopenia in U.S. adults aged 20–59: results from a cross-sectional study

Abstract

Background Sarcopenia, characterized by progressive loss of skeletal muscle mass and strength with pathophysiological changes that may originate in early life, and the Cardiometabolic Index (CMI) ‒ a reliable marker for lipid metabolic dysfunction and central adiposity ‒ have associations that are insufficiently studied. This study aimed to investigate the association between CMI and sarcopenia in U.S. adults aged 20–59 and to evaluate the predictive value of CMI for sarcopenia. Methods Utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2011–2018, which initially encompassed 39,156 participants, the authors applied age-based screening and exclusion of cases with missing data, resulting in a final analytical cohort of 4784 participants for statistical analysis. Sarcopenia was defined per the Foundation for the National Institutes of Health (FNIH) criteria: Appendicular Lean Mass (ALM) adjusted for BMI < 0.512 in men and < 0.461 in women. CMI was calculated as [triglycerides (mg/dL) / high-density lipoprotein cholesterol (mg/dL)] × [waist circumference (cm) / height (m)] / body mass index (kg/m2). Multivariate logistic regression, subgroup analysis (sex, age, race and clinical conditions), Generalized Additive Models (GAM), piecewise regression, Propensity Score Matching (PSM), Inverse Probability Weighting (IPW), and Receiver Operating Characteristic (ROC) curves were employed. Analyses were adjusted for three categories of confounders: sociodemographic factors, behavioral factors, and clinical factors. Results Among the 4784 participants, 425 (8.88%) had sarcopenia. Descriptive analysis showed that the median CMI of sarcopenia participants was higher (0.82 vs. 0.43; p < 0.001) compared with non-sarcopenia participants, and they had unfavorable demographic/clinical characteristics (e.g., older age, higher prevalence of diabetes). In the full sample, after adjusting for all confounding factors, Elevated CMI correlated with an increased odds of presenting sarcopenia (Odds Ratio [OR = 1.39], 95% CI = 1.05–1.91, p = 0.005). The multi-dimensional model incorporating CMI demonstrated superior predictive ability (AUC = 0.819). GAM revealed a non-linear association with a threshold of 0.899, which was strongest in males, individuals aged 20–39 years, non-Hispanic Blacks, those with hypertension, and non-obese or non-diabetic individuals. Conclusion Cardiometabolic Index (CMI) has a non-linear positive association with sarcopenia in U.S. young and middle-aged adults, with a threshold of 0.899. The multi-dimensional predictive model incorporating CMI demonstrates superior performance in assessing odds of presenting sarcopenia compared to traditional anthropometric indicators, indicating its potential as a novel clinical biomarker for such evaluations.