Increased market competition linked to higher odds of revascularization among asymptomatic patients with moderate carotid stenosis

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Caitlin W. Hicks and Rebecca Sorber

A vascular surgery research team with a growing reputation for its work investigating appropriateness in care in the peripheral vascular bed recently uncovered an association between increased regional market competition among proceduralists and higher odds of revascularization being carried out for moderate- versus high-grade asymptomatic carotid stenosis. The investigators detected no similar impact among symptomatic patients, leading Rebecca Sorber, MD, a general surgery resident at The Johns Hopkins University School of Medicine in Baltimore, and colleagues to conclude that a more competitive marketplace, or more physicians in a given region offering such carotid procedures, “may influence more aggressive behavior” when treating asymptomatic carotid disease patients who may otherwise be good candidates for surveillance. 

Senior author Caitlin W. Hicks, MD, associate professor of surgery at Johns Hopkins, told Vascular Specialist in an interview: “We do a lot of really important procedures and a lot of great care for patients but I also think we do too many procedures, or things that are not necessarily in patients’ best interests.” 

This latest project probing the contentious space of asymptomatic carotid intervention through the lens of market competition follows a body of work on atherectomy practice patterns and the appropriateness of its use, and was recently presented at the 2022 winter annual meeting of the Vascular and Endovascular Surgery Society (VESS), held in Snowmass, Colorado ( Jan. 27–30). 

“This one is a unique take on [that type of work], and it looks at the regional market competition characteristic, which is an interesting way to understand market influences, perhaps, in practice patterns,” Hicks explained. 

To arrive at their findings, Sorber, Hicks and colleagues plumbed the Vascular Quality Initiative (VQI) database for all patients undergoing first-time carotid revascularization for carotid artery stenosis of 50–99% between 2016–2020, stratifying them by symptomatology and degree of stenosis (moderate: 50–<80%; high grade: ≥80%). They then used 10 U.S. Health and Human Services (HHS) designated regions to measure competition amongst physicians, ultimately looking at nearly 150,000 patients. 

Competition by region was overall “quite high,” Sorber told VESS, which she said reflected the large number of proceduralists offering carotid revascularization in the U.S. The most competitive was the Great Lakes/Chicago region, with the least competitive identified as Denver/Rocky Mountains. Sorber revealed how a 10-point decrease in the Herfindahl-Hirschman Index (the measure the research team used to calculate physician market competition)— which corresponded to increased competition—was associated with an odds ratio of 1.02 increased likelihood of revascularization in moderate grade asymptomatic carotid stenosis versus those with high grade (95% confidence interval [CI] 1.01–1.03).

“As expected, an identical analysis in symptomatic patients showed no significant association between competition and revascularization threshold,” she told VESS. Furthermore, in-hospital outcomes showed that the moderate grade asymptomatic patients had a significantly higher likelihood of stroke and stroke-death following revascularization compared to their high-grade asymptomatic patients counterparts, Sorber said.

“Again, an identical analysis among symptomatic patients did not demonstrate this relationship, instead showing a slightly increased risk of mortality for high-grade patients.” Multivariable analysis demonstrated that moderate grade revascularization was independently associated with the composite adverse outcome of stroke-death among asymptomatic patients, Sorber added. 

Sitting alongside Hicks later, Sorber detailed how much of her mentor’s work has focused on disease processes that have clearer guidelines of what physicians should be carrying out. In those cases, she said, “we can really make judgments on whether what people are doing is appropriate,” she said. “With asymptomatic carotid disease, we don’t necessarily have that—a lot of the new trials are still in progress. So, this is the right time to do this project and look at this data, but it’s a difficult time to contextualize the results.”

The bottom line though, Sorber told Vascular Specialist, is that the project uncovered data showing physicians surrounded by a lot more competitors who are also treating carotid disease were “more likely to offer an operation to somebody with a lower percentage of stenosis.” That was consistent with results derived from other analyses of surgical behavior in more competitive markets, she said. 

Summing up the group’s findings during VESS, Sorber pointed to “the small but significant increases in adverse perioperative outcomes demonstrated for moderate-grade asymptomatic patients” as highlighting a need for “critical reflection” about factors motivating decisions to offer revascularization to asymptomatic patients with less than 80% stenosis. “At a minimum,” she said “there is room for improvement in ensuring patients with asymptomatic carotid stenosis and symptomatic stenosis are on best medical therapy prior to revascularization” as the carotid space awaits results from trials such as CREST-2. 

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