From the Journals

Very-low-volume vascular surgery practice linked to worse outcomes

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Choosing volume thresholds

The delineation of a threshold number of cases of OAR and CEA below which surgeons should not be credentialed remains unclear, despite much discussion of the volume-outcome relationship in vascular surgery.

In the current endovascular era, OAR in particular has become increasingly less frequent, with a dramatic effect on trainee experiences. It is often proposed that these cases be limited to high-volume surgeons. Some are concerned, however, that this action will leave rural surgeons unprepared to deal with ruptured abdominal aortic aneurysm and will force patients to travel long distances.

Dr. Marc Schermerhorn

Dr. Marc Schermerhorn

Researchers have shown that transferring patients from low-volume to high-volume centers can improve outcomes and save lives. But what low volume is too low? Our research on the effect of surgeon volume on mortality after OAR suggests that a threshold of eight or fewer cases may be optimal (J Vasc Surg. 2017;65[3]:626-34). However, it may be more politically acceptable – and therefore more feasible – to work with a threshold that’s much lower. The data that this study presents may be a reasonable place to start.

Sarah E. Deery, MD, and Marc L. Schermerhorn, MD, are in the division of vascular and endovascular surgery at Beth Israel Deaconess Medical Center in Boston. These remarks are adapted from an editorial accompanying the study. They reported having no disclosures.



The very-low-volume practice of surgeons performing no more than one open abdominal aortic aneurysm repair (OAR) or carotid endarterectomy (CEA) per year has persisted in New York State and was associated with worse postoperative outcomes and longer lengths of stay in a cohort study of statewide hospital data.

The study examined inpatient data on elective OARs and CEAs performed from 2000 to 2014 in every hospital in the state.

While the numbers and proportions of very-low-volume surgeons decreased (44.6%-23% for OAR and 35.2%-18.1% for CEA) and the number of procedures performed by these surgeons also decreased (QAR, 346-47; CEA, 395-90), the data are “concerning” and elucidate the “persistence” of very-low-volume practice in open vascular surgery, said Jialin Mao, MD, of Cornell University, New York, and associates (JAMA Surg. doi: 10:1001/jamasurg.2017.1100).

Very-low-volume surgeons were significantly less likely to be vascular surgeons, compared with higher-volume surgeons for both OAR (23.9% vs. 63.9%) and CEA (14.6% vs. 51.7%), they reported.

Compared with patients treated by higher-volume surgeons, those whose OAR was performed by very-low-volume surgeons had a twofold higher risk of postoperative death (6.7% vs. 3.5%) after adjusting for patient risk factors, surgeon specialty, and facility characteristics. Patients of very-low-volume surgeons also had significantly higher odds of sepsis or shock (odds ratio, 1.45), prolonged length of stay (OR, 1.37) and 30-day readmission (OR, 1.19), although the latter was not significant.

Similarly, patients whose CEA was performed by very-low-volume surgeons had a significant 1.8-fold higher odds of experiencing postoperative acute myocardial infarction (1.5% vs. 0.5%) and stroke (3.5% vs. 2.1%). They also were significantly more likely to have 30-day readmission (OR, 1.30).

With both procedures, patients treated by very-low-volume surgeons tended to be younger and healthier (less likely to have two or more comorbidities). They also were more likely to be nonwhite or insured by Medicaid.

“It is reasonable to speculate,” the researchers wrote, “that those treated by very-low-volume surgeons were more likely to be socioeconomically disadvantaged.”

Notably, 30% of the very-low-volume practice occurred in New York City, “where accessibility to high-volume practitioners should generally be higher,” they said.

The findings “indicate the need to eliminate this type of practice, to restrict the practice of these very-low-volume surgeons or to force referrals to higher-volume and specialized surgeons, and to improve disparity in access to high-quality care for all patients,” they said.

The study was funded in part by the U.S. Food and Drug Administration. The researchers reported having no relevant conflicts of interest.

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