Statin use does not reduce risk of acute kidney injury following cardiac surgery

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Adults who received atorvastatin before, during and after cardiac surgery did not have a reduction in the risk of acute kidney injury compared with a placebo group, according to a double-blinded, placebo-controlled, randomized trial.

The researchers defined acute kidney injury as an increase of 0.3mg/dL in serum creatinine concentration within 48 hours of surgery. Previous studies found that acute kidney injury following cardiac surgery leads to higher rates of postoperative arrhythmias, respiratory failure, systemic infection and MI.

Lead researcher Frederic T. Billings IV, MD, of the Vanderbilt University School of Medicine in Nashville, Tenn., and colleagues published their results online in JAMA on Feb. 23.

The study included 615 adults who underwent elective CABG, valvular heart surgery or ascending aortic surgery at the Vanderbilt University Medical Center from November 2009 to October 2014. Of the patients, 199 were naïve to statin treatment and 416 were already taking a statin.

The patients who were naïve to statin treatment were randomly assigned to receive 80 mg of atorvastatin the day before surgery, 40 mg of atorvastatin the morning of surgery (at least three hours before surgery) and 40 mg of atorvastatin at 10 a.m. each day following surgery for the duration of their hospital stay or matching placebo. Patients who were already taking a statin continued on treatment until the day of the surgery and resumed that regimen after the procedure.

The median age of patients was 67, while 30.6 percent were women and 32.8 percent had diabetes.

The researchers found that 20.8 percent of patients who received atorvastatin and 19.5 percent of patients who received placebo had acute kidney injury. The median serum creatinine concentration levels increased by 0.07 mg/dL in both groups.

Of the patients who were naïve to statin treatment, 21.6 percent of patients who received atorvastatin and 13.4 percent of patients who received placebo had acute kidney injury. Of the patients who were already taking a statin, 20.4 percent and 22.4 percent of patients, respectively, had acute kidney injury.

In addition, of the patients with chronic kidney disease at baseline, 35.7 percent of patients who received atorvastatin and 32.6 percent of patients who received placebo had acute kidney injury.

Further, 1.6 percent of patients in the atorvastatin group and 1.0 percent of patients in the placebo group required dialysis following acute kidney injury.

Of the 124 cases of acute kidney injury, 85.4 percent were classified as stage 1; 4.8 percent were stage 2; and 9.7 percent were stage 3. The researchers defined stage 1 acute kidney injury as an increase of 0.3 mg/dL or 50 percent in serum creatinine; stage 2 as a 100 percent increase; and stage 3 as a 200 percent increase or initiation of renal replacement therapy.

The researchers mentioned that 1.9 percent of patients in the atorvastatin group and 1.6 percent of patients in the placebo group had proximal muscle myalgias during the first three days following surgery. They added that there was no increase in creatinine kinase and aspartate aminotransferase concentrations on the first day following surgery.

The study had a few limitations, according to the researchers, including that it was only conducted at one center and that the patient population was at low risk for stage 2 or 3 acute kidney injury or other severe clinical outcomes. They also used used the Acute Kidney Injury Network (AKIN) criteria for diagnosing acute kidney injury, but they did not use the urine output AKIN criteria.