Surgeon Volume Impacts Mortality in Aneurysm Repair

A new study reveals that for open repair of intact elective abdominal aortic aneurysms (AAAs), surgeon annual volume rather than institutional volume is more strongly associated with decreased in-hospital mortality.

Researchers at the University of Massachusetts Medical School (Worcester, USA) reviewed the US Nationwide Inpatient Sample (2003-2007) to identify all patients who underwent open repair (5,972 patients) or endovascular aneurysm repair (EVAR, 1,821 patients) for nonruptured AAAs, in 11 participating US states that record a unique physician identifier for each procedure. Surgeon and institution volume were defined as low, medium, and high; stratification by institution volume and then by surgeon volume was performed to analyze the relative effects of both procedures' in-hospital mortality.

The researchers found a significant mortality reduction was associated with both annual institution volume and surgeon volume; high surgeon volume conferred a greater mortality reduction than did high institution volume. When low and medium volume institutions were stratified by surgeon volume, mortality after open AAA repair was inversely proportional to surgeon volume (8.7%, 3.6%, and 0% for low-, medium-, and high-volume surgeons at low-volume institutions, respectively; and 6.7%, 4.8%, and 3.3% for low-, medium-, and high-volume surgeons at medium-volume institutions). High-volume institutions stratified by surgeon volume demonstrated the same trend; however, this finding was not statistically significant. The study was published in the March 2011 issue of the Journal of Vascular Surgery.

"We believe that it is a shortcoming of publicly reported data and volume-based studies to consider EVAR and open AAA repair together, as it can be misleading,” said study coauthor Andres Schanzer, MD, a surgeon at the division of vascular and endovascular surgery. "For example, from an open surgical perspective, it is inappropriate to categorize a center as a high volume AAA institution based on the fact that they perform 50 EVAR's per year and 5 open AAA repairs per year. The reverse also is true, from an EVAR perspective, at a center that performs 50 open AAA repairs per year and 5 EVARs per year.”

According to the researchers, an important finding of the study is that the data indicated that elective EVAR of intact AAAs show universally low mortality rates (2%), regardless of surgeon or hospital experience.

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