Use of a lower cut-off value for HbA1c to predict postoperative renal complication risk in patients undergoing coronary artery bypass grafting.

ABSTRACT

OBJECTIVE: There is an increasing interest in reexamining the relationship between glucose levels and postoperative complications. Threshold levels of HbA1c below those currently recommended may be additional indicators of risk for renal and cardiovascular dysfunction. In this study, the authors analyzed the perioperative outcomes of coronary artery bypass graft (CABG) operations to evaluate the association of HbA1c levels and renal complications. DESIGN: Retrospective. SETTING: Research and training hospital, single institution. PARTICIPANTS: The prospectively collected data of 510 coronary bypass patients with documented HbA1c levels were analyzed. INTERVENTIONS: The relationship of HbA1c with postoperative renal morbidity was evaluated with logistic regression analysis with lower threshold value (5.9%) for elevated levels. MEASUREMENTS AND MAIN RESULTS: Two hundred ninety-three patients (57.5%) had elevated HbA1c values. Patients with high HbA1c levels (>5.9%) had higher incidences of atherosclerotic vascular diseases. The incidence of acute kidney injury was higher in the high HbA1c group (11.9% v 1.8%; p = 0.0001). The high HbA1c group had higher incidence of renal morbidity (odds ratio = 4.608), and every 1% increase over 5.9% increased risk of renal complications by 23.6%. The other factors associated with renal morbidity were known history of diabetes, chronic renal disease, and performance of any concomitant procedure. CONCLUSIONS: The elevated levels of HbA1c are associated with increased renal complications and the cut-off values of HbA1c could be lowered to the upper range of normal limits.