Albumin-corrected anion gap and mortality risk in cardiorenal syndrome: Insights from a nationally representative cohort study

The prognostic significance of the albumin-corrected anion gap (ACAG) in patients with cardiorenal syndrome (CRS) remains unclear. This study aimed to examine the association between ACAG and all-cause and cardiovascular mortality in a nationally representative cohort. We identified 1783 patients with CRS from the National Health and Nutrition Examination Survey 2005 to 2018 cycles and categorized them into terciles based on ACAG levels. Associations between ACAG and mortality were assessed using Cox regression, Kaplan–Meier survival curves, and restricted cubic spline analyses, with subgroup analyses across demographic and clinical strata. Among 1783 CRS patients, with a median follow-up time of 72 months, 859 deaths occurred, of which 36% were cardiovascular. Higher ACAG was independently associated with increased risks of all-cause mortality (hazard ratio [HR] = 1.14, 95% confidence interval [CI]: 1.09–1.18) and cardiovascular mortality (HR = 1.14, 95% CI: 1.08–1.21). A linear dose–response relationship was observed, and associations were consistent across subgroups. Elevated ACAG is significantly associated with higher risks of all-cause and cardiovascular mortality in CRS patients. To our knowledge, this is the first study to demonstrate the prognostic value of ACAG in CRS, highlighting its potential as a simple, inexpensive, and widely available marker for risk stratification in nephrology practice.