Associations between diuretic efficiency and mortality outcomes in cardiac intensive care unit patients

BACKGROUND: Diuretic efficiency (DE) is a measure of the urinary response to diuretics. Poor DE, or diuretic resistance (DR), is linked to adverse outcomes, but limited quantitative information exists for cardiac intensive care unit (CICU) patients. OBJECTIVE: Investigate the association between DE and mortality outcomes in CICU patients. METHODS: This historical cohort study included 3229 adult CICU patients (2007-2018) who received diuretics on day 1 of admission. Patients with a CICU stay <1 day or oliguria were excluded. DE was defined in increments of urine output (UOP) (mL) per 40 mg oral furosemide equivalent (FSE), and DR as <500 mL UOP per 40 mg FSE. Multivariable regression models were adjusted for confounders. RESULTS: Median DE was 760 (370, 1460) mL/40 mg PO FSE; 1098 (34.0%) patients had DR. In-hospital mortality was 9.8%. DE was continuously and inversely associated with in-hospital (adjusted OR 0.96 [0.94-0.98] per 100 mL/40 mg PO FSE, p < 0.001) and one-year mortality (adjusted HR 0.97 [0.97-0.98] per 100 mL/40 mg PO FSE, p < 0.001). DR was independently associated with higher in-hospital (adjusted OR 2.00 [1.51-2.64], p < 0.001) and one-year mortality (adjusted HR 1.64 [1.44-1.88], p < 0.001), and higher prevalence and severity of acute kidney injury (AKI). Patients with both AKI and DR had the highest mortality during and after hospitalization. These associations persisted in the heart failure subgroup. CONCLUSION: Reduced DE and DR independently predict higher in-hospital and one-year mortality in CICU patients, including those with heart failure. DE demonstrates potential as a readily available and valuable risk stratification tool.