The choice to use regional anesthesia rather than general anesthesia for total knee arthroplasty correlates strongly with an anesthesiologist’s board-certification status, new research shows.

The study found that, compared with their board-certified counterparts, non–board-certified anesthesiologists were more likely to use general anesthesia than neuraxial anesthesia or peripheral nerve blocks. A growing body of evidence shows that neuraxial anesthesia leads to better outcomes for patients than general anesthesia in joint replacement procedures, although the authors of the latest study cautioned that this is not universally agreed on.

Previous studies also suggested that the disparity in treatment choices might exist between board-certified and non–board-certified practitioners. None, however, had been conducted on such a large scale.

“The results are what we had hypothesized, but there are many factors that can contribute to the decision regarding the anesthetic technique,” said Peter M. Fleischut, MD, assistant professor in the Department of Anesthesiology at NewYork-Presbyterian Hospital/Weill Cornell Medical College, in New York City, and a co-author of the study. “For example, in this dataset non–board-certified anesthesiologists tended to take care of older patients” with a higher American Society of Anesthesiologists (ASA) surgical status.

The results do not warrant drawing any conclusions about individual practitioners based on their board certification status, but rather raise questions about these larger-scale practice patterns that merit further investigation, according to the researchers, who presented their findings at the ASA’s 2013 annual meeting (abstract 1001).

Emerging Findings From AQI

The study is one of the first to use data in the National Anesthesia Clinical Outcomes Registry (NACOR), collected by the Anesthesia Quality Institute (AQI). Researchers examined approximately 97,000 NACOR records for patients who underwent total knee arthroplasty surgery between 2010 and 2013 in which the anesthesiologist’s board certification status was available. Board-certified anesthesiologists attended to 82% of these patients. Board-certified anesthesiologists provided general anesthesia for this procedure less frequently than non–board-certified anesthesiologists (36% vs. 62%, respectively). Board-certified anesthesiologists used either neuraxial or regional anesthesia in 41% of the procedures, whereas non–board-certified anesthesiologists used these techniques 21% of the time.

Regardless of why a given anesthesiologist might choose general over regional anesthesia for a knee replacement procedure, patients are entitled to care that leads to the best possible outcomes, said Stavros Memtsoudis, MD, PhD, clinical professor of anesthesiology and of public health at Weill Cornell Medical College, and the study’s senior author.

Dr. Memtsoudis said previous work, including a recent study of his own published inAnesthesiology (2013;118:1046-1058), found that using regional anesthesia for total knee replacements is associated with better outcomes, including decreased blood loss, lower risk for blood clots, fewer organ-specific complications and decreased mortality.

“These population-based database studies that we provide don’t really allow us to establish a causal relationship. We can’t account for all covariates that may play a part when it comes to outcomes,” Dr. Memtsoudis said. “What I always clarify is that our data provide information on associations. Thus, we can conclude that patients who received a neuraxial anesthetic in this cohort did better across a wide range of outcomes.

“However, can we conclusively say that it was because of the neuraxial anesthetic? Not for sure; it may be, for example, that the performance of neuraxial anesthetics is a marker of a certain type of practice in a certain hospital,” he added. “For example, it may reflect that staff at these hospitals may be better trained to care for a particular patient group, they may be more involved, or may be part of a comprehensive perioperative practice that overall promotes better outcomes. Therefore, the question regarding what factors may contribute to the specific practice pattern is something we are looking into right now.”

Dr. Memtsoudis and his colleagues will be publishing a study in Regional Anesthesia and Pain Medicine assessing whether neuraxial anesthesia is equally effective in reducing complications in patient subpopulations of different age and comorbidity burden.

“From a patient perspective, it may not matter as much if the effects are due to cause or represent just an association,” Dr. Memtsoudis said. “Because if a patient chooses a place that provides neuraxial anesthesia for their cases, and they know that it is associated with better outcomes, then patients may not care whether it’s because neuraxial anesthesia is a marker of better care, or it’s because of the neuraxial anesthetic itself that better outcomes are achieved.”

Perhaps more significant than the findings regarding practice patterns, at least from a research perspective, were the methods used to conduct this study, Dr. Fleischut said.

“The most significant feature of this study was the large volume of data available to test the proposed hypothesis. As with other big data studies, having a wealth of information available permits an accurate identification of factors contributing to the outcome under investigation,” he said. In addition, the benefit of AQI data is that the data are from so many practices and providers throughout the country, even if some data are missing.”

Richard Dutton, MD, MBA, executive director of the AQI, agreed, saying that NACOR opens up valuable opportunities for anesthesiologists to better understand and examine practice patterns in their discipline.

“The whole purpose of NACOR is to inform us about ourselves—what we do and how we do it,” Dr. Dutton said. “And this was a particular study that demonstrated a substantial variability in practice. I think we’re going to see a lot more studies showing that variations in practice have important consequences for patients.”

John Laur, MD, MS, medical director of the ambulatory surgery center at the University of Iowa Hospitals and Clinics in Iowa City, said he expects the study to generate some valuable hypotheses. For instance, smaller hospitals may hire nurse anesthetists rather than anesthesiologists, for financial reasons, or the non–board-certified anesthesiologists in the study may be recent graduates who are unfamiliar with the use of neuraxial anesthesia.

“One thing about these large database studies is that the methodology continues to improve for using them appropriately,” Dr. Laur said. “I think that people do need to understand the caveats of these types of studies, in that they’re more for helping to create understanding of possible causes that we could design a more thorough study to look into.”