Association between preoperative level of hemoglobin A1c and the incidence of acute kindey injury after coronary artery bypass grafting surgery: a cohort study

Abstract

Background The development of acute kidney injury (AKI) is an important indicator of clinical outcomes after cardiac surgery. Elevated preoperative hemoglobin A1c level may be associated with acute kidney injury in patients undergoing coronary artery bypass grafting. This study will investigate the association of preoperative HbA1c levels with AKI after isolated coronary artery bypass grafting (CABG). Results Forty patients undergoing elective CABG were enrolled in this cohort study. Patients are divided into 2 equal groups who underwent isolated coronary artery bypass grafting (CABG): patients with preoperative HbA1c 5.7–6.4% (group A) (prediabetics) and patients with preoperative HbA1c > or = 6.5% (group B) (diabetics). Acute kidney injury according to the Kidney Disease: Improving Global Outcomes criteria developed in 11 patients (27.5%). There was a significant difference between the two groups as regards postoperative urinary NGAL, creatinine level on the 1st day, creatinine level on the 2nd day, urine output on the 1st day, and urine output on the 2nd day (p value was 0.001, 0.002, 0.006, 0.0002, and 0.012 respectively). Postoperative ICU stay duration was statistically significant in the diabetic group (P value 0.009). The need for renal replacement therapy was higher in the diabetic group, but it was not statistically significant between the two groups. Roc analysis shows AUC 0.922 with a significant p value (< 0.0001) and cut of value (≥ 7) with sensitivity 81.82 and specificity 93.10. Conclusion This study revealed that elevated preoperative HbA1c level above 7% showed an increase in incidence of post CABG acute kidney injury along with increase length of postoperative ICU stay.