Keeping Kidneys Safe
Kidney injury during surgery linked to long-term risk of cardiovascular disease
By Karin Lillis
When patients undergo surgery, they are at risk for kidney injury, which can occur when kidneys suddenly can’t filter waste from blood. UF Health researchers have found that when patients experience this type of kidney injury, they also stand an increased long-term risk of dying from cardiovascular disease.
The researchers hope their findings will lead to improved prevention, treatment and follow-up care for patients who sustain acute kidney injury during or after vascular surgery.
Chronic kidney disease is a well-known risk factor for cardiovascular mortality, the researchers noted. The current study, however, found that the risk of cardiovascular mortality among patients with acute kidney injury during vascular surgery was on par with that of patients who were diagnosed with chronic kidney disease.
Third-year UF College of Medicine student Matthew Huber is the first author on the paper, which appears in print and online in the journal JAMA Surgery.
“Anything that blocks the blood flow to the kidney, or blocks the flow of urine, can put a patient at risk for acute kidney injury,” said Charles Hobson, M.D., one of Huber’s mentors and a surgical intensivist at the Malcom Randall VA Medical Center in Gainesville. That can include preexisting kidney disease, diabetes and high blood pressure, as well as drugs that are toxic to the kidneys, or heavy and unexpected bleeding.
Specifically, the UF team linked acute kidney injury to an increased risk of dying from cardiovascular disease — even in cases where acute kidney injury was successfully treated and resolved after surgery. Among the 1,577 patients in the study who died, heart disease was the most prevalent cause — 53.6 percent, or 845 patients.
“There is a long-term risk of death from cardiovascular disease that is associated with acute kidney injury during vascular surgery, even if it has responded to treatment. Even patients who develop less severe acute kidney dysfunction and do not progress to complete kidney failure have an increased risk of heart disease,” Huber explained.
He participated in the project during the Medical Student Research Program fellowship in 2015 under the mentorship of Azra Bihorac, M.D., an associate professor of anesthesiology, medicine and surgery at UF College of Medicine. The study involved 3,646 patients who underwent inpatient vascular surgery between January 2000 and November 2010 at a large academic medical institution. The UF researchers noted that nearly half of those patients were diagnosed with acute kidney injury during surgery.
“What’s unique about this paper is that Matt and Dr. Bihorac are able to look at the long-term outcomes of perioperative acute kidney injury in patients who have had vascular surgery. We’ve always looked at patients with renal disease or acute kidney injury and thought they were markers for long-term outcomes — but there might be more to it,” said Salvatore Scali, M.D., an assistant professor of surgery in the division of vascular surgery and endovascular therapy at the UF College of Medicine.
He is one of the paper’s authors, as was Hobson.
“This is another study in a growing body on literature on the importance of mild and moderate acute kidney injury — conditions that were not even appreciated as disease until recently,” said Hobson.
The current paper builds on research by Bihorac and Hobson.
“We already know from our past work among patients undergoing different types of surgical procedures — and specifically among patients undergoing vascular surgery — that acute kidney injury is more common and has greater morbidity and mortality than has been appreciated in the past,” Bihorac explained.
There are two implications to this study: better prevention, treatment and follow-up care for patients who have acute kidney injury and improved cardiovascular follow-up after vascular surgery, Scali said. He hopes this study — and others like it — will increase awareness among both providers and patients and lead to improved standards of care.
“We have been able to show that it’s applicable in all surgical settings — there is an association between acute kidney injury and cardiovascular mortality independent of primary diagnosis,” Bihorac added.
Her team recently published a study that links acute kidney injury after all types of major surgical procedures with increase in cardiovascular mortality. That paper is published online ahead of the print edition in the journal Annals of Surgery.