Associations Between Albumin-Corrected Anion Gap and Mortality in Heart Failure Patients with Chronic Obstructive...

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are common comorbidities in intensive care unit (ICU) patients. The albumin-corrected anion gap (ACAG) has shown utility in predicting mortality across various populations; however, its impact on HF patients with COPD remains unclear. This study investigated the relationship between ACAG and mortality in this population.

We conducted a retrospective cohort study using the Medical Information Mart for Intensive Care (MIMIC)-IV database. A total of 1283 patients with heart failure and chronic obstructive pulmonary disease were included from the MIMIC-IV database. ACAG levels were assessed within 24 hours of admission. The association between ACAG and in-hospital and 30-day mortality was analyzed using Kaplan-Meier analysis, multivariate Cox regression, restricted cubic spline (RCS) analysis, subgroup analysis, and receiver operating characteristic (ROC) curve analysis.

Among 1283 HF patients with COPD (54.6% male), in-hospital and 30-day mortality rates were 11.2% and 13.7%, respectively. Kaplan-Meier analysis demonstrated significantly increased mortality risk in patients with higher ACAG levels (log-rank P<0.001). In fully adjusted Cox models, compared to the lowest ACAG group (T1), the highest group (T3) showed hazard ratios of 2.04 (95% CI: 1.18-3.54; p=0.011) for in-hospital mortality and 1.83 (95% CI: 1.12-2.97; p=0.015) for 30-day mortality. RCS analysis revealed a linear relationship between ACAG and mortality risk, consistent across subgroups. ROC analysis demonstrated superior discriminatory ability of ACAG for in-hospital mortality (AUC=0.693) compared to anion gap (AUC=0.571) and albumin (AUC=0.640), with similar findings for 30-day mortality.

ACAG is closely associated with the risk of mortality in HF patients with COPD. It appears to be a potential prognostic predictor for HF patients with COPD, aiding in risk stratification for this population. However, further prospective studies are needed to consolidate our findings.