Author: Michael Vlessides
Perioperative acute injury to the kidney is associated with the development and progression of chronic kidney disease in the year following non-cardiac surgery, a study has concluded.
The team of researchers at Duke University Medical Center did not observe a dose-response relationship between acute kidney injury (AKI) severity and subsequent risk for chronic kidney disease.
“The association between postoperative acute kidney injury and the progression of chronic kidney disease has been shown in the cardiac surgery literature,” said Mohammad R. Rasouli, MD, a clinical fellow in anesthesia critical care at Duke, in Durham, N.C. “Nevertheless, there is a lack of data in the non-cardiac surgery population.
“The idea came from our friends in Iceland,” Dr. Rasouli said. “So, we started a collaboration with them and used their database to help test this potential relationship.”
Dr. Rasouli and his colleagues identified all patients who underwent cardiac and non-cardiac surgeries between 1997 and 2015 at a university hospital in Iceland. “There are slightly more than 300,000 people in Iceland,” he said, “and most patients are referred to one of two big centers. This particular database comprises approximately 200,000 cases.”
As part of the study, serum creatinine levels were used to identify AKI stage within seven days of surgery, using criteria from the Kidney Disease: Improving Global Outcome (KDIGO) guidelines (Table). The primary outcome was one-year progression of chronic kidney disease of at least one stage in patients with preexisting chronic kidney disease. The development of new chronic kidney disease in patients without preexisting kidney disease also was examined.
Perioperative AKI Linked to Chronic Disease
The study involved 69,419 cases that met inclusion criteria, of whom 1,696 developed perioperative AKI (2.4%). Of those patients, 1,358 were AKI class 1 (80%), 197 were AKI class 2 (12%), and 141 (8%) were AKI class 3 (8%).
Moreover, the study showed that 342 of 1,023 patients (33.4%) who did not have pre-existing chronic kidney disease developed the condition within a year of AKI.
“It wasn’t necessarily high-grade chronic kidney disease that required renal replacement therapy,” Dr. Rasouli said in an interview with Anesthesiology News at the 2019 annual meeting of the International Anesthesia Research Society (abstract C134). “But we still feel it’s very important that new chronic kidney disease developed in these patients.”
Similarly, 269 of 673 patients (39.9%) with pre-existing chronic kidney disease saw their disease worsen within a year of AKI development.
Perhaps not surprisingly, perioperative AKI was found to be significantly associated with the progression of chronic kidney disease at one year after surgery (P<0.05). Nevertheless, the analysis did not reveal a dose-response relationship between the level of preoperative renal function and hazard ratio for development of chronic kidney disease one year after surgery.
“You might expect that if there’s more severe AKI then you are more likely to have chronic kidney disease progression,” Dr. Rasouli said. “But we were surprised that we didn’t see anything like that.”
Although the investigators were confident in their findings, Dr. Rasouli was quick to point out that the study population is unique. “Icelandic people may have slightly different genetics than North Americans. They don’t have quite as much genetic diversity. But considering the lack of data in this patient population, we still believe the findings are surprising and interesting.”
Assuming the findings are applicable to a broader population, Dr. Rasouli believes they indicate that maintaining healthy kidney function throughout surgery—both cardiac and non-cardiac—is paramount to long-term patient well-being. “Obviously we know that we have to maintain blood pressure at optimal levels during surgery, as well as in the postoperative period,” he explained. “We also have to make sure we hydrate our patients enough, while making sure not to overhydrate or underhydrate, as both have been associated with poor outcomes. Finally, we need to be really careful with any potentially nephrotoxic drugs our patients may be taking or contrast imaging we may use in the perioperative period.
“But at the end of the day,” Dr. Rasouli said, “the message from these data is that any perioperative AKI is associated with increased risk of chronic kidney disease progression.”
The findings came as little surprise to Nader D. Nader, MD, PhD, whose 2018 study yielded similar results (Curr Med Res Opin 2018;34:1829-1837). “In our study, we examined the Veterans Affairs Surgical Quality database, and we found that not only is perioperative AKI a risk factor for chronic renal insufficiency later, but it also increases the chance of mortality,” he told Anesthesiology News.
Certain risk factors can play a role in the development of AKI, Dr. Nader said, offering clinicians an opportunity to stem the development of chronic kidney disease. “One of these risk factors is preoperative hemoglobin level,” said Dr. Nader, a professor of anesthesiology and research professor of pathology at the State University of New York at Buffalo. “We should make sure patients are not anemic when they undergo surgery.
“Other strategies include maintaining patients’ mean arterial pressure, as well as avoiding transfusion and certain vasoconstrictors such as vasopressin, which decrease blood flow to the kidneys,” Dr. Nader added.