Although patients with chronic kidney disease (CKD) who present for surgery are often instructed to stop certain medications preoperatively, a study from New York University Langone Medical Center has concluded that such cessation may be largely unnecessary. The researchers found that five common agents—angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blockers, diuretics, statins, insulin and calcium channel blockers—do not have a significant effect with respect to preventing postoperative complications. In contrast, β-blockers increase the likelihood of readmission.
“Here at NYU Langone, we have a robust presurgical testing clinic, and we’re in the process of trying to identify the highest-risk population that comes through the clinic,” said Samir Kendale, MD, assistant professor of anesthesiology at the New York City institution. “While we were doing this, we discovered that chronic kidney disease patients tend to have a greater number of complications across the board.
“Our next thought was to help these patients,” he continued. “Are there perioperative protocols that we can perform that may reduce these outcomes? Along those lines, we thought that we would see how medication management may affect postoperative outcomes.” Indeed, the perioperative effects of medications commonly prescribed to slow the progression of CKD are unclear.
To help shed some light on the issue, Dr. Kendale and his colleagues used a cohort of patients with reduced estimated glomerular filtration rate (<60 mL/1.73 m2/min) from a database of adult patients who underwent elective surgery at the institution between June 2011 and July 2013. Patients’ prescribed medications at the time of surgery were also taken from the database.
Patients were identified as either taking or not taking ACE inhibitors, angiotensin receptor blockers, diuretics, statins, β-blockers, insulin or calcium channel blockers. Logistic regression was used to analyze outcomes including acute kidney injury (AKI), myocardial infarction, infection, venous thromboembolism and readmission within 30 days.
In all, 2,865 patients were included in the analysis. Propensity matching created 250 to 1,100 pairs, depending on the medication. Analysis found no association between preoperative medications and outcomes of interest, except for a statistically significant association between β-blocker use and readmission within 30 days (Table).
“The most common complication we observed is acute kidney injury,” Dr. Kendale said in an interview with Anesthesiology News. “It turns out that it doesn’t matter if patients are taking a diuretic, calcium channel blocker or ACE inhibitor. It doesn’t have an effect whatsoever on whether they develop AKI or not.”
As Dr. Kendale reported at the 2015 annual meeting of the International Anesthesia Research Society (abstract S-308), the results proved surprising to the investigators. “We had supposed that there would be some effect,” he noted. “For example, we supposed that a diuretic would more likely lead to a higher incidence of AKI, because patients’ kidneys are damaged to begin with. But that was not the case, and that sort of pattern held true for all of these medications.”
Given these results, the researchers said there was little evidence that medications should be altered before surgery. “However, we have to be careful with the interpretation of our data,” he added. “It’s a retrospective study, so we can’t say a lot about actually stopping the medications in these patients. But we can say there is no real evidence to discontinue one medication or add another solely for the perioperative period. Currently, in our institution, we tell all our patients to continue their meds up to and including the day of surgery.”
Of note, the investigators also found a significant percentage of patients with CKD who were not diagnosed as such. “So not only are they at risk, but there’s a large percentage of them that we’re not capturing preoperatively,” Dr. Kendale explained.
Although there may be little association between medication use and outcomes, the issue does not end there. Indeed, identifying factors that are modifiable by medication management or lifestyle interventions is a critical step toward developing protocols to enhance patient safety and postoperative recovery in patients with CKD.
“That’s where we’re moving next,” Dr. Kendale said. “Is there something that needs to be done in the perioperative period or is it just a matter of medical management, wherein we identify these patients early on and make sure that their disease is managed properly?”
Further investigation, he added, is needed to determine the effect of factors such as surgical severity and smoking status on postoperative outcomes to define optimal management protocols.
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