Neutrophil To Lymphocyte Ratio And Lactate Dehydrogenase Predict The Postoperative Pneumonia Following Aneurysmal Subarachnoid Hemorrhage

Objective: Although a variety of risk factors of postoperative pneumonia(POP)in patients with aneurysmal subarachnoid hemorrhage(aSAH)have been studied,the predictive model of POP after aSAH has still been not well established,and more objective and easily accessible markers are still needed.Lactate dehydrogenase(LDH)is a non-specific inflammatory biomarker,and has been reported to be a useful predictor of community acquired pneumonia and mycoplasma pneumoniae pneumonia.However,the connection between LDH level and postoperative pneumonia(POP)in patients with aneurysmal subarachnoid hemorrhage(aSAH)is still unclear.The aim of this study was to assess the feasibility of using admission neutrophil to lymphocyte ratio(NLR)and lactate dehydrogenase(LDH)to predict occurrence of POP in aSAH patients.Methods: Information of aSAH patients administrated between January 2013 and June 2018 to the Department of Neurosurgery of the First Affiliated Hospital of Fujian Medical University was retrospectively reviewed.Among them,711 consecutive patients with aSAH had admitted neutrophil to lymphocyte ratio(NLR)data,647 consecutive patients with aSAH had admitted lactate dehydrogenase(LDH)data,which met the inclusion criteria.NLR was calculated as absolute neutrophil counts divided by absolute lymphocyte counts.The relationship between NLR?LDH at admission and POP was analyzed.Candidate pool of multivariate predictors included all available demographics and baseline variables that had univariate association P<0.10 with the occurrence of POP.The final model was created by performing backward stepwise multivariate regression to remove the least nonsignificant variables one by one,until all remaining variables had P<0.05.Best thresholds were derived from the receiver operating characteristic(ROC)curve analyses and used to calculate the corresponding sensitivities,specificity and Youden index of the predictive factors.Area under the curve(AUC)model performance was tested using the Z test.The percentage of patients surviving POP for 30 days after surgical treatment was calculated using Kaplan–Meier method,the survival curves were drawn and compared using the log-rank test.P ? 0.05 was considered significant.Results: 1.The study of the relationship between NLR at admission and POP included 711 aSAH patients,of which 219 patients(30.4%)had POP.Patients with POP had significantly higher NLR than those without(14.11±8.90 vs.8.80±5.82,P<0.001).After adjusting for possible confounding factors,multivariate analysis revealed that NLR remained a significant factor independently associated with POP following aSAH [OR=1.078(1.042-1.116),P<0.001].Moreover,the age,World Federation of Neurosurgical Societies(WFNS)grade,interventional treatment,and ventilator use were also significant predictors of POP,independent of NLR.Receiver operating characteristic curve analysis showed that NLR had a sensitivity of 63.5% and a specificity of 70.7% for predicting POP based on the best threshold of 10.04.The predictive value of WFNS grade was significantly increased after NLR was combined with WFNS grade [interaction: WFNS grade × ln(NLR)] [AUC=0.798(0.761-0.835)vs.AUC=0.838(0.816–0.859),Z=2.030,P=0.042].Post-hoc log-rank testing revealed that good grade patients having NLR > 10 had significantly worse POP survival rate than good grade patients having NLR ? 10;and a similar result was found in the poor grade patients.2.The study of the relationship between LDH at admission and POP included 647 aSAH patients,of which 187 patients(28.90%)had POP.Patients with POP had significantly higher LDH level than those without(261.26±126.51 U/L vs.189.00±69.20 U/L,P<0.001).Multivariate analysis showed that LDH level remained a significant independent factor associated with POP in aSAH patients,even after adjusting for possible confounding factors.Receiver operating characteristic curve analysis showed that LDH level had a sensitivity of 63.6% and a specificity of 71.3% for predicting POP based on the best threshold of 203.5U/L.When patients were classified by WFNS or MV use,regardless the WFNS grade(WFNS<3 or ?3)or length of MV use(0-24 hours or ?24 hours),the POP free survival rate of patients having admission LDH>=250U/L was significantly worse than those with LDH<250 UL.Conclusions: NLR and LDH at admission might be helpful as a predictor of POP in aSAH patients,and when NLR used in combination with the clinical grade of the severity can improve its predictive power.