Association between admission undernutrition and mortality rates and adverse outcomes in a pediatric intensive care unit in India: a prospective cohort study.

Background: Undernutrition is common in critically ill children in resource-limited settings. However, it remains unclear whether its association with pediatric intensive care unit (PICU) outcomes persists after rigorous adjustment for illness severity, particularly with the use of mortality prediction scores developed in high-income populations. Therefore, in this study, we examined whether undernutrition at admission was associated with mortality and adverse outcomes in an Indian tertiary care PICU. Methods: We conducted a prospective cohort study between August 2022 and June 2024 in a 16-bed mixed medical-surgical PICU at a tertiary university hospital in India. The study included 331 critically ill children aged 1 month to 18 years with complete data. Undernutrition was defined using the World Health Organization and Indian Academy of Pediatrics growth standards (z-score < -2 SD) measured within 24 h of admission. The primary outcome was PICU mortality rate. Adjusted risk ratios (aRRs) were estimated using modified Poisson regression, adjusting for Pediatric Index of Mortality (PIM-3)-predicted mortality, sepsis, age, and chronic comorbidities. Results: At admission, 60 (18.1%) children were undernourished. The PICU mortality rate was 13.9% overall, 30.0% among undernourished children, and 10.3% among well-nourished children. After multivariable adjustment, undernutrition was associated with a higher mortality risk [aRR 2.78, 95% confidence interval (CI) 1.58-4.91], corresponding to an adjusted absolute risk difference of 18.6 percentage points. The association persisted in the propensity score-weighted analysis (aRR 2.59, 95% CI 1.34-5.03) but was attenuated when extreme illness severity was excluded from the analysis. Undernutrition was also associated with mechanical ventilation (66.7% vs. 35.4%; aRR 1.84, 95% CI 1.40-2.41), extended PICU stay (61.7% vs. 37.0%; aRR 1.56, 95% CI 1.17-2.09), and the death-or-mechanical ventilation composite (66.7% vs. 36.2%; aRR 1.76, 95% CI 1.35-2.30) in full-cohort analyses designed to avoid survivor-restriction bias. The observed mortality substantially exceeded the PIM-3 predictions (standardized mortality ratio, 4.63), particularly in undernourished children (standardized mortality ratio, 7.90). Conclusion: In this Indian cohort, undernutrition at admission was associated with higher PICU mortality and adverse outcomes after adjusting for illness severity. In high-burden, resource-limited settings, anthropometric screening may aid risk stratification. However, causal inference remains limited by the observational design and substantial miscalibration of the illness severity score.