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Open AAA repair mortality rates doubled for very-low-volume surgeons



NEW YORK – If New York State is representative, the risk of bad outcomes in patients undergoing open abdominal aortic aneurysm repair (OAR) or carotid endarterectomy (CEA), including death in the case of OAR, is about double when performed by very low- versus higher-volume surgeons, according to data presented at a symposium on vascular and endovascular issues sponsored by the Cleveland Clinic Foundation.

Dr. Jack L. Cronenwett, professor of surgery, Geisel School of Medicine at Dartmouth, Hanover, N.H.

Dr. Jack L. Cronenwett

“What should we do to fix the problem? We could require surgeons to track their outcomes in quality improvement registry,” suggested Jack L. Cronenwett, MD, professor of surgery, Geisel School of Medicine at Dartmouth, Hanover, N.H.

The outcomes were evaluated from inpatient data gathered from patients undergoing OAR or CEA in an all-payer database involving every hospital discharge in New York State. Surgeons were defined as very-low-volume for a given procedure if they averaged one or less per year, though the results held true if very-low-volume was defined as less than three cases per year, according to Dr. Cronenwett.

The database had outcomes on 8,781 OAR procedures and 68,896 CEA procedures performed from 2000 to 2014.

Of the 614 surgeons who performed one or more OARs over this period, 318 (51.8%) were defined as low-volume surgeons. Despite their substantial representation, they performed just 7.6% of the procedures.

When outcomes from procedures performed by very-low-volume surgeons were compared to those done by higher-volume surgeons, the mortality rates without adjustments were nearly double (6.7% vs. 3.5%; P less than .001). Procedures performed by low-volume surgeons were associated with far higher rates of sepsis or shock (5.7% vs. 3.7%; P = .008), and patients treated by low-volume surgeons were more likely to spend 9 or more days in the hospital (39.3% vs. 30.1%; P less than .001).

When fully adjusted for other variables, “low-volume surgeons had twofold higher odds [OR 2.09] of postoperative death,” Dr. Cronenwett reported.

Of the 1,071 surgeons who performed CEA over this period, 512 (47.8%) were low-volume. They performed 1.3% of the procedures.

Mortality and sepsis or shock following CEA were less than 1% in procedures performed by either low- or higher-volume surgeons without significant differences. However, procedures performed by low-volume surgeons were associated with a three-times higher rate of myocardial infarction (1.5% vs. 0.5%; P less than .001) and a 65% higher rate of stroke (3.5% vs. 2.1%; P = .003).

In addition, patients who underwent CEA performed by a low-volume surgeon had a significantly higher rate of 30-day readmission (11.5% vs. 8.5%; P = .002) and a significantly longer median length of stay (2 days vs. 1 day; P less than .001) than did those treated by a higher-volume surgeon.

Whether OAR or CEA, patients treated by a low-volume surgeon were more likely to have Medicaid coverage. The fact that procedures by low-volume surgeons were more likely to be performed in New York City than other areas of the state suggest that access to care was not a variable, according to Dr. Cronenwett.

Surgeon volume was calculated in this study by dividing the total number of OAR or CEA procedures performed by the number of years that the surgeon was in practice in New York State. Surgeons were classified as vascular surgeons if 75% or more of their surgical practice involved vascular procedures, cardiac surgeons if more than 20% of their surgical practice involved cardiac procedures, and general surgeons if they did not meet either of these criteria.

Of OAR procedures were done by a higher-volume surgeon, approximately 65% were by vascular specialists, 5% were by cardiac specialists, and the remaining were by general surgeons.

Of OAR procedures were done by a low-volume surgeon, approximately 25% were by vascular surgeons, 20% were by cardiac surgeons, and the remaining were by general surgeons. For CEA, there was a somewhat greater representation of general surgeons in both categories, but the patterns were similar.

Dr. Cronenwett argued that more rigorous steps should be taken to ensure that those with proven skills perform OAR and CEA and that open abdominal aortic aneurysm repair should be performed only by high-volume surgeons and hospitals. He suggested there are a variety of incentives or disincentives that could help, but he stressed the importance of tracking results and making them available to referring physicians and to patients.

“Some of the low-volume surgeons are probably not tracking their results so are not even aware of these bad outcomes,” he added.

Dr. Cronenwett reported that he had no relevant disclosures.

SOURCE: Cronenwett JL et al. 2018; VEITHsymposium.

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