Surgeon specialization may predict 30-day operative mortality following cardiac procedures

A surgeon’s degree of specialization helped predict 30-day operative mortality in some common cardiology procedures, according to a retrospective analysis of Medicare data.

The researchers calculated surgeon specialization by dividing the number of times the surgeon performed the specific procedure by his or her total number of operations for all procedures.

Surgeons who were in the top quarter of specialization for carotid endarterectomy, CABG, valve replacement and abdominal aortic aneurysm repair had a significant relative risk reduction in operative mortality compared with those in the bottom quarter of specialization. The results were independent of the number of times the surgeon performed the procedure.

Lead researcher Nikhil R. Sahni, MD, MPH, of Harvard University, and colleagues published their results online in BMJ on July 21.

This analysis included 25,152 surgeons who performed one of the following eight procedures between 2008 and 2013: carotid endarterectomy, CABG, valve replacement, abdominal aortic aneurysm repair, lung resection, cystectomy, pancreatic resection or esophagectomy. They performed the procedures on 695,987 patients who were at least 66 years old and were continuously enrolled in fee-for-service Medicare from 12 months before the hospital admission through four months after the admission.

The mean surgeon specialization ranged from 6 percent for esophagectomy to 40 percent for CABG. Within the procedures, the difference in specialization among the surgeons ranged from 43 percentage points for esophagectomy to 94 percentage points for CABG.

The relative risk reduction in 30-day operative mortality between the bottom and top quarters of surgeon specialization was 15 percent with CABG, 28 percent with carotid endarterectomy, 42 percent with abdominal aortic aneurysm repair and 46 percent with valve replacement.

Based on procedure volume, the relative risk reduction in 30-day operative mortality between the bottom and top quarters of surgeons was 35 percent with CABG, 18 percent with carotid endarterectomy, 74 percent with abdominal aortic aneurysm repair and 22 percent with valve replacement.

The researchers identified a few possible explanations for the association between specialization and outcomes. They said that repeating the surgery may help surgeons improve their muscle memory and dexterity and become more familiar with the medical devices. In addition, by concentrating on one procedure, they become more of an expert in that area and do not have other distractions.

They added that there were some potential limitations of the study, including that surgeons might choose certain patients who are healthier than others. They also did not account for the surgeon’s technical skill, age, experience or training history. In addition, the study was limited to Medicare fee-for-service beneficiaries, so they did not know all of the procedures that the surgeons performed.

“We have been careful not to suggest that surgeons should specialize more, as that would require establishment of a causal relation,” the researchers wrote. “In all of our examples, surgeons’ specialization is used as a surrogate for surgeons’ quality, much like procedure specific volume is used as a proxy for surgeons’ quality. Whether the degree of specialization causally improves surgical quality remains a topic for future work.”