The following article features coverage from Kidney Week 2019. Click here to read more of Renal & Urology News’ conference coverage.

WASHINGTON—Lower hemoglobin levels independently predict an elevated risk of a major adverse kidney event among patients undergoing cardiac surgery or who are admitted to an intensive care unit (ICU), according to study findings presented at the American Society of Nephrology’s 2019 Kidney Week conference. Decreasing hemoglobin levels are associated with increases in these events.

Anemia is a well-known risk factor for acute kidney injury (AKI), but all prior studies have examined anemia as a dichotomous (yes or no) variable, first author Samuel Short, BA, a medical student at the University of Vermont Larner College of Medicine, told Renal & Urology News.

“We examined the effect of hemoglobin both categorically and continuously in the settings of cardiac surgery and critical illness to further examine the role that degree of anemia plays in AKI risk,” Short said. “In both of these settings, hemoglobin was monotonically and independently associated with a composite end point, including AKI, need for dialysis, or death.”

AKI risk stratification models should include continuous hemoglobin value rather than the presence or absence of anemia to best identify high-risk patients, he and his colleagues concluded.

The study included 21,598 cardiac surgery patients and 74,557 ICU. The main study outcome was a major adverse kidney event within 7 days (MAKE7) of cardiac surgery or ICU admission. Of the cardiac surgery and ICU patients, 1322 (6.1%) and 6343 (8.5%) experienced MAKE7, respectively. The investigators defined MAKE7 as 100% or greater increase in serum creatinine, dialysis, or death.

Among patients who had cardiac surgery, a hemoglobin level below 9 g/dL was significantly associated with 7.3-fold greater odds of a major adverse kidney event within 7 days (MAKE7) compared with a hemoglobin level of 13g/dL or higher after adjusting for preoperative serum creatinine level and other potential confounding variables, Short and colleagues reported in a poster presentation. Each 1 g/dL decrease in hemoglobin level was significantly associated with 1.4-fold higher odds of MAKE 7 in adjusted analyses.

Among ICU patients, a hemoglobin level below 7 g/dL was significantly associated with a 3.3-fold increased odds of MAKE 7 compared with a level of 13 g/dL or higher after adjusting for baseline serum creatinine and other potential confounding variables. Each 1 g/dL decrease in hemoglobin levels was significantly associated with 1.1-fold increased odds of MAKE7.

“Future studies should examine whether strategies to raise hemoglobin could prevent or attenuate the effects of AKI in these settings,” Short said.

Read more of Renal & Urology News’ coverage of Kidney Week 2019 by visiting the conference page.

Reference

Short S, Chander S, Waikar SS, et al. Hemoglobin is a strong and independent predictor of  major adverse kidney events. Presented at the American Society of Nephrology’s 2019 Kidney Week conference held November 5 to 10 in Washington, DC. Abstract TH-PO059.