Platelet-to-Lymphocyte ratio (PLR) is a Novel Independent Risk Factor for Newborn Patients in the Neonatal Intensive Care Unit (NICU)

Abstract Objective: To investigate the prognostic significance of the platelet-to-lymphocyte ratio (PLR) for newborn patients in the neonatal intensive care unit (NICU).Design: A retrospective cohort study.Setting and participants: Data on 5240 newborn patients in the NICU extracted from the Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC III) database.Methods: Spearman correlation was used to analyze the association of PLR with length of hospital and ICU stays. The chi-square test was used to analyze the association of PLR with mortality rate. Multivariable logistic regression was used to determine whether the PLR was an independent prognostic factor of mortality. The area under the receiver operating characteristic (ROC) curve was used to assess the predictive ability of models combining PLR with other variables.Results: PLR was negatively associated with length of hospital stay and ICU stay (hospital stay: Spearman’s rho=-0.416, P<0.0001; ICU stay: Spearman’s rho=-0.442, P<0.0001). PLR was significantly correlated with hospital mortality (P<0.0001). Lower PLR was associated with higher hospital mortality (OR=0.85, 95% CI=0.75-0.95, P=0.005) and 90-day mortality (OR=0.85, 95% CI=0.76-0.96, P=0.010). The prognostic predictive ability of models combining PLR with other variables for hospital mortality was moderately good (AUC for Model 1=0.804; AUC for Model 2=0.964).Conclusion: PLR is a novel independent risk factor for newborn patients in the NICU.