Kidney Week

Abstract: SA-OR018

Hemoglobin A1c and Major Adverse Kidney Events After Cardiac Surgery

Session Information

• AKI: Risk Factors, Biomarkers, and Predictors
  November 09, 2019 | Location: Salon C, Walter E. Washington Convention Center
  Abstract Time: 05:54 PM - 06:06 PM

Category: Acute Kidney Injury

• 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

• Short, Samuel, Brigham and Women''s Hospital, Boston, Massachusetts, United States

Samuel Short



A native of Mukilteo, Washington, Sam Short is a first year medical student at the University of Vermont Larner College of Medicine. Sam became interested in nephrology while conducting clinical research at Brigham & Women's Hospital under the mentorship of Drs. David Leaf, Finnian McCausland, and Sushrut Waikar. Though he is not yet certain about his career path, he is excited to continue exploring nephrology as his training continues.

• Hundemer, Gregory L., Brigham and Women''s Hospital, Boston, Massachusetts, United States

Gregory L. Hundemer,

• Rawn, James, Brigham and Women''s Hospital, Boston, Massachusetts, United States

James Rawn,

• Axtell, Andrea L., Massachusetts General Hospital, Boston, Massachusetts, United States

Andrea L. Axtell,

• Leaf, David E., Brigham and Women''s Hospital, Boston, Massachusetts, United States

David E. Leaf,

Background

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.

Methods

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.

Results

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.

Conclusion

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

Funding

• NIDDK Support