The relationship between the length of hospital stay and innate cell function at admission or discharge

Abstract

This prospective observational study evaluated the association between length of hospital stay and the production of key macrophage-associated cytokines at admission and discharge in children with severe acute malnutrition (SAM). A total of 142 children aged 6–59 months from hospitals in Zimbabwe and Zambia were consecutively enrolled upon admission, with SAM diagnosed according to World Health Organization criteria. Peripheral blood samples were collected within 24 hours of admission and at discharge. Whole blood cultures were stimulated with three conditions: unstimulated control medium, lipopolysaccharide (LPS), and heat-killed Salmonella typhimurium. Concentrations of interleukin-1 beta (IL-1β), interleukin-4 (IL-4), interleukin-10 (IL-10), interferon gamma (IFN-γ), and vascular endothelial growth factor (VEGF) were measured by ELISA. Non-parametric tests, Spearman’s correlations, and logistic regression adjusted for confounders were applied. Lower pro-inflammatory responses (IL-1β, IFN-γ) and reduced VEGF production at admission were significantly associated with longer hospital stays (>17 days), while higher IL-10 responses correlated with prolonged recovery. IL- 4 showed a weaker, non-significant association. These findings suggest that immune profiles at admission may serve as early prognostic biomarkers for recovery time in pediatric SAM, supporting the integration of bedside immunological assessments into clinical triage and targeted care strategies