The rate of acute dialysis after elective major surgery tripled in Ontario between 1995 and 2009, new findings suggest. The increase was primarily among patients undergoing cardiac and vascular surgery.

The investigators, led by Amit Garg, MD, PhD, of the London Health Sciences Centre in London, Ontario, said they believe the cause may be an increase in proportion of individuals with preoperative chronic kidney disease who undergo major surgery. They are now testing interventions aimed at reducing the post-operative rates of acute kidney injury (AKI), particularly among patients with compromised kidney function before the surgery.

“One of our trials, which are all funded by the CIHR [Canadian Institutes of Health Research], is looking at the spice turmeric for the prevention of AKI in the elective abdominal aortic aneurysm repair setting, where there are high rates of AKI,” Dr. Garg told Renal & Urology News.

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Dr. Garg and his colleagues used data on hospital admissions from the Canadian Institute for Health Information’s discharge-abstract database, information on inpatient and outpatient services from the Ontario Health Insurance Plan, and vital statistics on all permanent Ontario residents from the Registered Persons Database.

They analyzed data from 552,672 adults admitted to hospital for an overnight stay for elective major surgery between January 1, 1995 and December 31, 2009.

“We wanted to restrict our analysis to people who had major surgery,” Dr. Garg said. “Day surgery procedures are much less invasive, and the complication rate there, particularly for acute kidney injury—whether it requires dialysis or not—has not been an important medical concern.”

The study showed that 50.6% of patients were 65 years and older in 2006-2009, compared with 39.5% in 1995-1997, according to a report published in the Canadian Medical Association Journal (2012;184:1237-1245). In addition, the researchers found an increase in the proportions of diseases associated with postoperative acute dialysis, such as diabetes and chronic kidney disease.

The incidence of post-operative acute dialysis increased steadily from 0.2% in 1995 to 0.6% in 2009. The increase occurred in all age groups, but primarily among those who underwent cardiac and vascular surgery. Dr. Garg’s team noted that “in recent years, as many as one in 80 patients had their cardiac surgery complicated by acute dialysis, compared to one in 390 in 1995.”

In addition, the time to the start of acute dialysis post-operatively grew shorter: In 1995, the first dialysis treatment was done a median of five days after surgery, and in 2009 it was two days.

The type of dialysis used also changed over time. After 1998, the researchers observed a shift almost completely away from peritoneal dialysis and toward continuous renal replacement therapy.

Among the 2,231 patients who receive post-operative acute dialysis, 937 deaths occurred within 90 days of surgery. The study did not show a significant change over time in 90-day post-operative mortality among those who received acute dialysis.