Association between hyperglycemia at ICU admission and postoperative acute kidney injury in patients undergoing cardiac surgery:Analysis of the MIMIC-IV database

Background:This study aimed to explore the correlation between hyperglycemia at intensive care unit(ICU)admission and the incidence of acute kidney injury(AKI)in patients after cardiac surgery.Methods:We conducted a retrospective cohort study,in which clinical data were extracted from the Medical Information Mart for Intensive Care(MIMIC)-IV database.Adults(≥18 years)in the database who were admitted to the cardiovascular intensive care unit after cardiac surgery were enrolled.The primary outcome was the incidence of AKI within 7 days following ICU admission.Secondary outcomes included ICU mortality,hospital mortality,ICU length of stay,and the 28-day and 90-day mortality.Multivariable Cox regression analysis was used to assess the association between ICU-admission hyperglycemia and AKI incidence within 7 days of ICU admission.Different adjustment strategies were used to adjust for potential confounders.Patients were divided into three groups according to their highest blood glucose levels recorded within 24 h of ICU admission:no hyperglycemia(<140 mg/dL),mild hyperglycemia(140-200 mg/dL),and severe hyperglycemia(≥200 mg/dL).Results:Of the 6905 included patients,2201(31.9%)were female,and the median(IQR)age was 68.2(60.1-75.9)years.In all,1836(26.6%)patients had severe hyperglycemia.The incidence of AKI within 7 days of ICU admission,ICU mortality,and hospital mortality was significantly higher in patients with severe admission hyperglycemia than those with mild hyperglycemia or no hyperglycemia(80.3%vs.73.6% and 61.2%,respec-tively;2.8%vs.0.9% and 1.9%,respectively;and 3.4%vs.1.2% and 2.5%,respectively;all P<0.001).Severe hyperglycemia was a risk factor for 7-day AKI(Model 1:hazard ratio[HR]=1.4809,95%confidence interval[CI]:1.3126 to 1.6707;Model 2:HR=1.1639,95%CI:1.0176 to 1.3313;Model 3:HR=1.2014,95%CI:1.0490 to 1.3760;all P<0.050).Patients with normal glucose levels(glucose levels<140 mg/dL)had a higher 28-day mortality rate than those with severe hyperglycemia(glucose levels≥200 mg/dL)(4.0%vs.3.8%,P<0.001).Conclusions:In post-cardiac surgery patients,severe hyperglycemia within 24 h of ICU admission increases the risk of 7-day AKI,ICU mortality,and hospital mortality.Clinicians should be extra cautious regarding AKI among patients with hyperglycemia at ICU admission after cardiac surgery.