Albumin-bilirubin score is independently associated with sarcopenia in U.S. adults: evidence from a national cross-sectional survey.

Background: the liver-muscle axis has been increasingly recognized as a critical pathway in age-related muscle decline. The albumin-bilirubin (ALBI) score, a simple and objective indicator of liver function, may be associated with sarcopenia, yet evidence from population-based studies remains limited. Methods: this cross-sectional study included 4,082 adult participants from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. Sarcopenia was defined using skeletal muscle index (SMI) derived from dual-energy X-ray absorptiometry. ALBI scores were calculated using serum albumin and total bilirubin. Weighted multivariable logistic regression and restricted cubic spline models were employed to evaluate the association between ALBI and sarcopenia. Subgroup analyses were conducted to explore potential effect modification. Results: participants with sarcopenia exhibited a higher mean ALBI score (-2.91 ± 0.28) compared to those without sarcopenia (-2.99 ± 0.26; p = 0.002). In the fully adjusted model, each one-unit increase in ALBI score was associated with a 2.41-fold increase in the odds of sarcopenia (95 % CI: 1.22 to 4.77; p = 0.012). A significant linear trend was observed across ALBI quartiles (p for trend = 0.033), and restricted cubic spline analysis confirmed a linear dose-response relationship (p for non-linearity > 0.05). Subgroup analyses showed that the association was more pronounced among individuals with obesity, elevated triglycerides, and current smoking status, with significant interaction effects. Conclusions: higher ALBI scores are independently associated with increased risk of sarcopenia in the general adult population. Given its accessibility and clinical utility, the ALBI score may serve as a practical biomarker for early identification of individuals at elevated risk of muscle loss, particularly among metabolically vulnerable subgroups.