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Kidney Week

Abstract: SA-OR018

Hemoglobin A1c and Major Adverse Kidney Events After Cardiac Surgery

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention


  • Short, Samuel, Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Hundemer, Gregory L., Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Rawn, James, Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Axtell, Andrea L., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Leaf, David E., Brigham and Women''s Hospital, Boston, Massachusetts, United States

Diabetes mellitus (DM) is a well-known risk factor for acute kidney injury (AKI). However, nearly all prior studies in the setting of AKI assessed DM as a dichotomous variable. We investigated whether hemoglobin A1c, assessed categorically and continuously, associates monotonically and independently with AKI following cardiac surgery.


We performed a retrospective cohort study in 15,892 patients who underwent cardiac surgery at two medical centers in Boston, MA, between 2008-2018. The primary exposure was the most recent A1c within 6 months prior to surgery. We assessed A1c in 6 categories: low (<5%), reference (5–5.6%), prediabetes (5.7–6.4%), well-controlled DM (6.5–6.9%), moderately-controlled DM (7–8.9%), and poorly-controlled DM (≥9%). The primary endpoint was any Major Adverse Kidney Event occurring within 7 days of surgery (MAKE7), defined as an increase in serum creatinine ≥50%, dialysis, or death. We used multivariable logistic regression to adjust for potential confounders.


The incidence of MAKE7 was 12%. Compared to the reference group, we observed a monotonic increase in the risk of MAKE7 with higher A1c categories. Patients with an A1c ≥9 vs. 5–5.6% had a nearly two-fold higher risk of MAKE7 in unadjusted models (odds ratio, 1.99; 95% CI, 1.56 to 2.53). We found similar results in multivariable adjusted models that included 13 key variables (Figure). We also found similar results in models that assessed higher stages of AKI. When assessed as a continuous variable, the adjusted odds ratio for MAKE7 per 1-percent increase in A1c was 1.10 (95% C, 1.05 to 1.15). Finally, patients with an A1c <5% also appeared to be at increased risk of MAKE7.


Both higher and lower hemoglobin A1c values are independently associated with higher risk of MAKE7 following cardiac surgery.


  • NIDDK Support