For reasons doctors don’t completely understand, this complication, which is called acute kidney injury (AKI) or acute renal failure, is on the rise, and it dramatically increases a patient’s risk of dying during recovery.
The study looked at rates of kidney injury in more than 200,000 senior surgical patients in Canada over 14 years. Researchers found that people who took statin medications had about a 16% reduced risk of renal failure and a 21% lower risk of dying after their surgeries, compared to people who weren’t taking the drugs.
“Our study suggests that statin use in older persons results in less kidney injury following major elective surgery and reduces the risk of premature death after surgery,” study researcher Amber O. Molnar, MD, a nephrologist at the University of Western Ontario in London, Canada, says in a news release.
Statins and Kidney Injury
For the study, researchers looked at the medical records of all seniors who had elective surgery in Ontario, Canada, from 1995 through 2008, a group of 213,347 men and women over age 65.
Elective procedures included heart or lung operations, vascular surgery, or surgery in the abdomen, or procedures on the bladder, ureter, or kidneys -- except transplants or removal of the kidneys. About half of patients in the study had heart surgeries.
Nearly one-third of these patients were taking statin medications before going under the knife.
Overall, about 2% of patients experienced renal failure within two weeks of their procedures.
For those taking statins, however, that risk of AKI was modestly reduced, by about 16%, even after researchers accounted for a host of other things that might have affected their results, like differences in age, sex, other kinds of heart medications, and complicating illnesses like diabetes.
Statin users also had a lower risk of death after surgery, about 20% less, compared to those who weren’t on the medications.
To see if the relationship between statins and kidney injury got stronger if patients were on stronger statin medications, researchers classified different statins as either high or low potency drugs.
People were classified as being on more potent statins if they were taking a drug or dose that had been proven in other studies to reduce LDL cholesterol by 45% or more.
People on these high-potency regimens saw their risk of kidney failure cut by 24% compared to those who weren’t taking statins. And compared to those on less powerful statins, those on high-potency prescriptions saw their risk of renal failure cut by an additional 15%.
Statins appeared to be protective even if patients had been on them a relatively short time, as little as a month or less before surgery.
How Statins May Protect the Kidneys
Acute kidney injury is a common complication after surgery. Depending on how researchers define it, studies have shown that it may occur in up to 40% of patients.
It’s more common in older patients and with heart procedures that require heart and lung bypass.
Though doctors don’t exactly know how or why it happens, it’s thought that the kidneys become deprived of oxygen, which causes a cascade of damage that in some cases may become serious enough to require dialysis.
Studies in animals suggest that statins may help by blocking some of the inflammatory damage that ultimately results in kidney failure.
But the study’s authors point out that more research will be needed before doctors can recommend using statins as a protective measure before an operation.
The study is published in the Journal of the American Society of Nephrology.