Correlation between albumin–bilirubin score and comorbidity of cardiovascular disease and chronic kidney disease: insights from NHANES 2011–2018

BACKGROUND: Growing evidence indicates that cardiovascular disease (CVD), chronic kidney disease (CKD), and liver dysfunction share common pathophysiological pathways and constitute an interconnected syndrome. The albumin-bilirubin (ALBI) score, originally developed to assess liver function, has shown prognostic value in various nonhepatic diseases. However, its association with the comorbidity of CVD and CKD remains unclear. This study aimed to investigate the association between ALBI score and CVD-CKD comorbidity and to explore potential intermediate factors in a nationally representative US adult population. METHODS: A cross-sectional analysis of 15,681 adults from the National Health and Nutrition Examination Survey (NHANES) 2011-2018 was conducted. The ALBI score was calculated as: (log10 bilirubin [μmol/L] × 0.66) + (albumin [g/L] × - 0.085). Weighted multivariable logistic regression, restricted cubic spline, threshold effect, subgroup, and mediation analyses were performed. RESULTS: After fully adjusting for confounders (age, sex, race, education level, poverty-income ratio, body mass index, hypertension, smoking, alcohol use, and diabetes), each one-unit increase in the ALBI score was associated with more than a 4.38-fold higher prevalence of cardiovascular disease-chronic kidney disease (CVD-CKD) comorbidity (OR = 5.38, 95% CI 3.84-7.54; P < 0.001). A nonlinear relationship was observed (nonlinearity test P < 0.001), with an inflection point at approximately - 3.436. Exploratory mediation analyses indicated that diabetes and the body roundness index (BRI) statistically accounted for about 5%-6% and 0.5% of the association, respectively. However, the proportion explained by reverse mediation (diabetes → ALBI → CVD-CKD) was larger, reaching up to 6.3%. CONCLUSION: Higher ALBI score is independently associated with increased odds of CVD-CKD comorbidity. The association appears to be largely driven by shared metabolic disturbances rather than liver dysfunction being upstream of diabetes or obesity. ALBI may serve as a simple, objective marker for early risk stratification in the cardiovascular-kidney-metabolic axis.