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Kidney Week

Abstract: TH-PO059

Hemoglobin Is a Strong and Independent Predictor of Major Adverse Kidney Events

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Short, Samuel, Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Chander, Subhash, Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Waikar, Sushrut S., Brigham and Women''s Hospital, Boston, Massachusetts, United States
  • Allegretti, Andrew S., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Leaf, David E., Brigham and Women''s Hospital, Boston, Massachusetts, United States
Background

Anemia is an established risk factor for acute kidney injury (AKI). However, most prior studies assessed anemia as a dichotomous variable, and were further limited by modest sample sizes, incomplete adjustment for confounders, and failure to account for dialysis and death as competing risks.

Methods

We performed a retrospective cohort study of patients who underwent cardiac surgery (CS) or were admitted to an ICU at two medical centers in Boston, MA, between 2005-2018. We excluded patients with ESRD and those who already had AKI. Our final cohort included 18,784 CS and 30,633 ICU patients. The primary exposure was the most proximal Hgb before surgery or ICU admission. The primary endpoint was any Major Adverse Kidney Event within 7 days (MAKE7) after CS or ICU admission. MAKE7 was defined as an increase of serum creatinine (SCr) ≥100%, dialysis, or death. We used multivariable logistic regression to adjust for potential confounders.

Results

The incidence of MAKE7 was 6% in the CS cohort and 14% in the ICU cohort. In both cohorts, we observed a monotonic increase in risk of MAKE7 with lower Hgb values. Patients who underwent CS with a Hgb<9 vs. 12-15 g/dL had a 7.3-fold (95% CI, 5.7-9.4) higher risk of MAKE7 in a model adjusted for preoperative SCr, urgent/emergent surgery, and 11 additional key variables. Additionally, each 1 g/dL decrease in Hgb associated with a 1.6-fold higher risk of MAKE7 in adjusted models (95% CI, 1.5-1.7). ICU patients with a Hgb<6 vs. 12-15 g/dL had a 2.3-fold (95% CI, 1.9-2.9) higher risk of MAKE7 in a model adjusted for baseline SCr, sepsis, shock, mechanical ventilation, and 13 additional key variables.

Conclusion

Lower Hgb associates monotonically, independently, and strongly with higher risk of MAKE7 in patients undergoing CS and in those admitted to the ICU.

Funding

  • NIDDK Support