Background
Revascularization practices with respect to asymptomatic carotid stenosis (ACAS) are
known to vary widely among proceduralists. In addition, regional market competition
has been previously shown to drive more aggressive practices in a number of surgical
procedures. The aim of our study was to examine the association of regional market
competition with revascularization thresholds for ACAS.
Methods
All patients undergoing carotid revascularization in the Vascular Quality Initiative
carotid endarterectomy and stenting databases (2016–2020) were included. High-grade
carotid stenosis was defined as ≥80%. We calculated the Herfindahl-Hirschman Index
(HHI; a measure of physician market competition) for each U.S region as defined by
the U.S Department of Health and Human Services. Logistic regression was used to examine
the association of degree of carotid stenosis at revascularization with HHI stratified
by symptomatology, adjusting for age, sex, race, insurance, and revascularization
modality.
Results
Of 92,243 carotid interventions, 57,094 (61.9%) were performed for ACAS and 35,149
(38.1%) were performed for symptomatic carotid stenosis (SCAS). ACAS patients undergoing
revascularization for moderate-grade stenosis were significantly less likely to be
aspirin (85.6% vs. 86.3%), clopidogrel (41.3% vs. 45.1%), dual anti-platelet therapy
(35.9% vs. 39.2%) and systemic anticoagulants (10.9 vs. 11.7%) compared to high-grade
stenosis (all P < 0.05). Multivariable analysis demonstrated that decreased local market competition
was independently associated with a lower odds of revascularization for moderate versus
high-grade ACAS (odds ratio OR: 0.99 per 10 point increase in HHI, 95% confidence
interval CI: 0.98–0.99). There was no association of local market competition with
degree of carotid stenosis at time of revascularization among patients with SCAS (OR:
1.00 per 10 point increase in HHI, 95% CI: 0.99–1.00). Among ACAS patients, patients
with moderate-grade stenosis had a higher odds ratio of in-hospital stroke or death
compared to patients with high-grade stenosis (OR: 1.22, 95% CI 1.03–1.45). This association
was not redemonstrated in the SCAS group (OR: 0.92, 95% CI: 0.80–1.06).
Conclusions
Increased local market competition is associated with a lower threshold for revascularization
of ACAS. There is no association between regional market competition and revascularization
threshold for SCAS. These findings, combined with the significantly increased risk
of perioperative stroke/death among moderate-grade ACAS patients, suggest that competition
among proceduralists may result in a higher tolerance for increased operative risk
in patients who might otherwise be reasonable candidates for surveillance.
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Article Info
Publication History
Published online: August 04, 2022
Accepted:
July 11,
2022
Received:
March 20,
2022
Publication stage
In Press Journal Pre-ProofFootnotes
Prepared for the 2022 Vascular and Endovascular Surgical Society Winter Meeting, Snowmass, CO.
Conflicts of interest: The authors declare that they have no conflicts of interest or relevant financial relationships to disclose. This work did not receive specific grant funding from any public or private institution or individual.
Author contributions: RS and CWH conceived and designed the study. Statistical analysis was carried out by CMH, and the results analyzed and interpreted by RS, CMH, DZ, CA, JB, GW and CWH. The article was written by RS and all authors approved the final manuscript. Overall responsibility for this work is assumed by CWH as senior author.
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