Anemia prior to cardiac surgery is associated with adverse outcomes among patients with chronic kidney disease (CKD), new findings suggest.

In a prospective observational study of 788 CKD patients undergoing open heart surgery, researchers found that each 1 g/dL decrement in preoperative hemoglobin was associated with a 38%, 31%, 31%, and 38% increased risk of death, sepsis, cerebrovascular accident (CVA), and acute kidney injury (AKI) requiring hemodialysis, respectively.

The study, led by Linda Shavit, MD, of Shaare Zedek Medical Center in Jerusalem, Israel, also showed that, compared with a preoperative hemoglobin level above 14 g/dL, levels below 12 g/dL were independently associated with a significant 2.5 times increased risk of death. Preoperative hemoglobin levels below 11 g/dL were independently associated with a significant 3.8 times increased risk of sepsis. Preoperative hemoglobin levels below 12, 11, and 10 g/dL were independently associated with a 2.7, 4.5, and 4.7 times increased risk of kidney failure.

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“Similar to the general population, preoperative anemia is associated with adverse postoperative outcomes in patients with CKD,” the investigators wrote in a paper published online ahead of print in the Clinical Journal of the American Society of Nephrology. Whether outcomes could be improved by therapeutically targeting higher preoperative hemoglobin levels before cardiac surgery in patients with underlying CKD remains to be determined.”

Of the 788 patients in the study, 22.5% had preoperative hemoglobin in the normal range (men: 14–18 g/dL; women: 12–16 g/dL). Twenty-three patients (2.8%) experienced postoperative AKI requiring dialysis, 20 (2.5%) had a CVA, 74 (9.2%) experienced sepsis, and 96 (12%) died.

Dr. Shavit’s group acknowledged that their study was limited by the use of observational data, so they could not entirely rule out known or unknown confounding factors in explaining their results. In addition, data on the preoperative use and dose of erythropoiesis-stimulating agents were not recorded consistently and could not be analyzed.