Association of monocyte to lymphocyte ratio with length of stay in intensive care unit in neonatal apnea modified by treatment.

Background: Apnea is a common condition among neonates admitted to the intensive care unit (ICU), often leading to prolonged hospitalization and increased healthcare burden. This study aimed to investigate the association between monocyte to lymphocyte ratio (MLR) and length of stay (LOS) in the ICU among neonates diagnosed with apnea.

Methods: Data were extracted from the Medical Information Mart for Intensive Care III (MIMIC III) database. Collinearity analysis excluded variables with a variance inflation factor >2. Generalized additive models (GAM) explored the nonlinear relationship between MLR and ICU LOS. Three generalized linear models (GLMs) assessed associations between MLR and LOS, adjusting for various factors. Mediation analysis evaluated MLR's role between intraventricular hemorrhage (IVH)/caffeine/mechanical ventilation and LOS in the ICU.

Results: A total of 1,120 neonates with apnea were included in this study. Neonates in the high MLR group had a significantly longer LOS in the ICU compared to the low MLR group. GAM analysis indicated a non-linear relationship between MLR and LOS in the ICU. In adjusted GLM analyses, higher MLR levels were positively correlated with increased LOS in the ICU {β=5.576 [95% confidence interval (CI): 2.270, 8.881], P=0.001} and LOS in the hospital [β=5.529 (95% CI: 2.237, 8.820), P=0.001]. Subgroup analyses revealed that MLR's association with LOS in the ICU was influenced by IVH and treatments such as caffeine and mechanical ventilation, with mediation analysis confirming MLR as a mediator in these contexts.

Conclusions: MLR is significantly associated with increased LOS in the ICU among neonates with apnea, with treatment factors modifying this relationship.