Risk Factors And Prognosis Analysis Of Acute Kidney Injury In Traumatic Brain Injury Patients

BackgroundsMannitol is widely used because of its osmotic diuretic action,however,it may accumulate leading to potentially kidney injury which hasn't been paid full attention. In recent decades,more and more cases were reported who developed acute renal failure(ARF) following massive mannitol infusion,but there was few of large-scale study to access the relationship between mannitol and kidney injury.Patients with traumatic brain injury,who are commonly prolonged high-dose mannitol,are the high-risk group of acute kidney injury(AKI).Recently,AKI has taken place of ARF and a new definition and the RIFLE staging criteria of AKI recommended by Acute Dialysis Quality Initiative(ADQI) Group have been used for early diagnosis of AKI. However,there was few study about the risk factors and prognosis of AKI defined by this criteria in traumatic brain injury patients,which will also help to get a better understanding of mannitol intoxication to kidney.We retrospectively studied this cohort,aiming to determine the risk factors of AKI complicated by traumatic brain injury,and to establish the predictive model of AKI in traumatic brain patients and especially the role of mannitol.Besides,we tried to analyze the prognosis and evaluate the link between AKI and the outcome.methods(1)We retrospectively studied a random cohort of traumatic brain injury patients who were admitted to Neurosurgical emergency center of Huashan Hospital,Fudan University from January 2006 to December 2008.AKI was determined using the RIFLE staging criteria for changes in creatinine,and the control group was random selected from the patients admitted in the same period without AKI.By means of logistic regression analysis,we investigated the risk factors of AKI,and established a predictive model.We assessed the discrimination of our model using the receiver operating characteristic(ROC) curve.The relationship between the single independent risk factor and AKI was depicted with an ROC curve.Adjustment for selection bias was further assessed using Propensity Score Match(PSM) to evaluate the role of mannitol in the development of AKI.(2)Kaplan-Meier survival curves were used to investigate the relationship between AKI stages and survival rate.The COX regression model was used in multivariate analysis to identify the prognosis factors for survival. The predictive value for prognosis by the RIFLE stage was evaluated with an ROC curve.Results(1)We retrospectively studied a random cohort of 171 patients who were admitted because of traumatic brain injury,with 53 patients in AKI group and 118 patients without AKI as control group.The number of male was 131,which was 3.275-fold more than which of female.The average age of the 171 patients was 45.92±16.50 years.Univariate analysis revealed that age,hypertension,emergent surgery,systemic inflammatory response syndrome(SIRS),Glasgow Coma Score(GCS),Sequential Organ Failure Assessment(SOFA) Score,the respiration component of the SOFA score,the coagulation component of the SOFA score,the cardiovascular component of the SOFA score,mechanical ventilation time,red blood cell transfusion,plasma transfusion,the accumulative dose of furosemide,the accumulative dose of torasemide and the accumulative dose of mannitol were significantly related to AKI in traumatic brain injury patients.Logistic multivariate regression analysis showed that SOFA score (OR=1.516,95%CI 1.222-1.881,P＜0.001),the accumulative dose of torasemide (OR=0.016,95%CI 1.002-1.031,P=0.016),the accumulative dose of mannitol (OR=2.687,95%CI 1.062-6.800,P=0.037) were independent risk factors of AKI.This model had a good discrimination for AKI with an area under the ROC curve of 0.901 (P＜0.001).PSM method were tested,and the accumulative dose of mannitol as a risk factor of AKI was identified.(2)The prognosis of traumatic brain injury with AKI was poor,with the 28 days mortality of non-AKI group,Injury group,Risk group and Failure group was 2.5%,21.7%,30.0%and 70.0%,respectively.The Kaplan-Meier analysis showed that the 28 days survival was significant different among the four group(P＜0.001).The hospital mortality of non-AKI group,Injury group,Risk group and Failure group was 3.4%,26.1%,30.0%and 90.0%,respectively.The Kaplan-Meier analysis also showed that the hospital survival was significant different among the four group(P＜0.001).Univariate analysis revealed that age,hypertension, emergent surgery,serum creatinine on admission,GCS,SOFA score,the respiration component of the SOFA score,the coagulation component of the SOFA score,the cardiovascular component of the SOFA score,plasma transfusion,the accumulative dose of furosemide,the accumulative dose of mannitol and the RIFLE stage of AKI were significantly related to 28 days mortality.The COX regression analysis showed that the cardiovascular component of the SOFA score(HR=1.551,95%CI 1.174-2.049, P=0.002) and the RIFLE stage(HR=2.219,95%CI 1.412-3.212,P＜0.001) were risk factors of 28 days mortality.The RIFLE stage of AKI had a good predictive value for 28 days mortality with an area under the ROC curve of 0.848(P＜0.001).ConclusionAKI is a common complication in traumatic brain injury patients,and the accumulative dose of mannitol is an independent risk factor of AKI.AKI is related directly to the prognosis of traumatic brain injury patients,and even small changes in Scr concentration are associated with increased mortality.The 28 days mortality and hospital mortality are both inceased with the progression of the RIFLE stage.The RIFLE stage have a good predictive value for 28 days mortality.