Absolute lymphocyte count as a predictor of mortality and readmission in heart failure hospitalization.

Background: There is renewed interest in pursuing frugal and readily available laboratory markers to predict mortality and readmission in heart failure. We aim to determine the relationship between absolute lymphocyte count (ALC) and clinical outcomes in patients with heart failure hospitalization. Methods: This was a retrospective cohort study of patients with heart failure. Patients were divided into two groups based on ALC, less than or equal to 1500 cells/mm3 and > 1500 cells/ mm3. The primary outcome was all-cause mortality. We did subgroup analysis based on ejection fraction and studied the association between ALC categories and clinical outcomes. Both ALC groups are matched by propensity score, outcomes were analyzed by Cox regression, and estimates are presented in hazard ratios (HR) and 95% confidence intervals (CI). Results: We included 1029 patients in the pre-matched cohort and 766 patients in the propensity-score matched cohort. The median age was 64 years (IQR, 54-75), and 60.78% were male. In the matched cohort, ALC less than or equal to 1500 cells/mm3 had a higher risk of mortality compared with ALC > 1500 cells/mm3 (HR 1.51, 95% CI: 1.17-1.95; P = 0.002). These results were reproducible in subgroups of heart failure. When ALC was divided into four groups based on their levels, the lowest group of ALC had the highest risk of mortality. Conclusions: In patients with heart failure and both subgroups, ALC less than or equal to 1500 cells/mm3 had a higher risk of mortality. Patients in lower groups of the ALC categories had a higher risk of mortality.