The Relationship Between Neutrophil-to-Lymphocyte Ratio and Clinical Outcomes in Pediatric Patients After Cardiopulmonary Bypass Surgery: A Retrospective Study

Objectives: This study aimed to evaluate the prognostic utility of the neutrophil-to-lymphocyte ratio (NLR) and the perioperative change in NLR [Neutrophil Change Index (NCI)] in pediatric patients undergoing surgery with cardiopulmonary bypass (CPB) and to assess their correlations with clinical outcomes. Methods: A retrospective observational study was conducted with 416 patients from Children’s Medical Center in Tehran, Iran, spanning November 2021 to November 2022. Perioperative neutrophil and lymphocyte counts were collected, along with data on the presence or absence of complications. The prognostic value of NLR and NCI was evaluated concerning the length of ICU stay and mechanical ventilation among three groups: A no-complications survival group, a complications survival group, and a mortality group. Results: All patients showed an average rise in NLR postoperatively. The postoperative NLR magnitude did not significantly differ among the groups (P = 0.237) and was only correlated with mechanical ventilation duration (P = 0.0497), not with ICU stay length. However, the NCI was significantly lower in the mortality group compared to both the no-complication and surviving-complication groups (P < 0.001 and P = 0.032). Neutrophil Change Index also showed a statistically significant correlation with ICU stay and mechanical ventilation duration (P = 0.004 and P = 0.002). ROC analysis indicated that NCI had some ability to discriminate mortality cases, with an AUC of 0.734. Conclusions: While NLR showed perioperative changes, its magnitude alone was not correlated with clinical outcomes. In contrast, the NCI demonstrated a significant relationship with outcomes, with surviving-complication patients having a higher perioperative NCI than those in the mortality group. A higher NCI was associated with shorter ICU stays, reduced mechanical ventilation time, and lower mortality risk in pediatric patients undergoing CPB surgery. Overall, NCI proved to be a more effective tool than NLR in predicting adverse outcomes in this patient population.