Prognostic value of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in critically ill children – a retrospective cohort study from a tertiary care pediatric intensive care unit

Background: Early risk stratification is essential in pediatric intensive care. Simple, inexpensive biomarkers are needed, especially in resource-limited settings. We evaluated the prognostic value of trends in neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) for predicting mortality in critically ill children and compared their performance with the pediatric logistic organ dysfunction-2 (PELOD-2) score. Methods: The study consisted of children aged 1 month to 18 years admitted to the pediatric intensive care unit (ICU) of Navodaya Medical College Hospital and Research Centre, Raichur, India from January 2024 to December 2025 with a stay ≥5 days. Various ratios were calculated on days 1 and 5. PELOD-2 was calculated on admission. The primary outcome was PICU mortality. Trends were compared between survivors and non-survivors. Results: Among 100 children (mean age 5.2±3.8 years, 60% male), overall mortality was 20% (n=20). Sepsis was the most common diagnosis (45%). Non-survivors showed a marked increase in NLR (day 1: 6.8±2.2; day 5: 12.5±3.6) and PLR (day 1: 180±55; day 5: 320±80), whereas survivors exhibited decreasing trends (NLR: 4.5±1.8 to 3.2±1.4; PLR: 140±45 to 110±40). Between-group differences in day 5 NLR and PLR were highly significant (p<0.001). PELOD-2 was higher in non-survivors (14.8±4.1 versus 6.2±2.5, p<0.001). ROC analysis yielded AUCs of 0.82 (95% CI 0.73-0.91) for day 5 NLR, 0.79 (95% CI 0.69-0.89) for day 5 PLR, and 0.86 (95% CI 0.78-0.94) for PELOD-2 (p<0.001 for each). Optimal cut-offs (NLR ≥7.2, PLR ≥210) gave sensitivities of 83% and 80%, and specificities of 78% and 75%, respectively. Conclusions: An increase in the PL ratio and the NL ratio over the first five PICU days had a strong association with the outcome in terms of mortality. These simple markers can complement established scores for dynamic risk assessment, particularly in resource-constrained settings.