Cardiologists Perform Bulk of Carotid Stenting Procedures
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In many areas of the country, cardiologists perform far more carotid artery stenting (CAS) procedures than surgeons and neurologists, according to a study published online August 8, 2011, ahead of print in the Archives of Internal Medicine. Differences also exist in the characteristics of patients treated by the various specialties, and higher stenting rates are seen in hospital referral regions where cardiologists predominate.
For the study, investigators led by Brahmajee K. Nallamothu, MD, MPH, of the University of Michigan Medical School (Ann Arbor, MI), examined national data from the Centers for Medicare and Medicaid Services on elderly Medicare beneficiaries who underwent CAS between 2005 and 2007 in 306 hospital referral regions.
Patient Characteristics, Regional Use Vary
Overall, 2,588 operators performed 28,700 CAS procedures. While cardiologists accounted for approximately one-third of all operators, they were responsible for 52% of total procedures. They were followed by surgeons (27.3%) and radiologists (17.8%), with the few remaining procedures (3.2%) performed by other specialties largely represented by neurology and internal medicine. Among surgeons, vascular surgeons made up the largest group (62.4%), followed by general surgeons (20.8%), neurosurgeons (7.9%), and cardiothoracic surgeons (7.9%).
Over the study period, CAS procedures increased annually across all specialties but the growth was most prominent for cardiologists and surgeons. Although the patients treated by cardiologists did not differ by sex or race compared with those seen by other specialists, they tended to be slightly younger.
Cardiologists also were more likely than the other specialists to perform procedures in patients with at least 1 comorbidity related to cardiovascular conditions but less likely to do so in those with neurological conditions. In addition, rates of cardiac catheterization (with or without concomitant carotid X-ray angiography) and coronary intervention in the 180 days prior to CAS were significantly higher in procedures performed by cardiologists. However, recent diagnosis of acute stroke or transient ischemic attack (TIA) during the same period prior to carotid stenting was less common in this group (table 1).
Table 1. CAS Patient Characteristics Across Specialties
|
Cardiologists |
Surgeons |
Radiologists |
Other |
Cardiac Comorbidity |
69.1% |
62.8% |
61.2% |
63.7% |
Neurological Comorbidity |
15.9% |
21.1% |
25.8% |
22.7% |
Cardiac Catheterization ≤ 180 Days |
27.0% |
12.6% |
11.0% |
17.1% |
Catheterization + |
14.1% |
3.0% |
2.0% |
5.7% |
Coronary Intervention ≤ 180 Days |
10.0% |
3.8% |
3.7% |
6.1% |
Stroke or TIA ≤ 180 Days |
44.1% |
53.2% |
56.1% |
64.2% |
P < 0.001 for all endpoints.
The proportion of carotid stenting performed by cardiologists within hospital referral regions varied substantially across the United States, ranging from none in 2 regions to 100% in 1 region (mean 45.5%). Cardiologists performed most procedures in 42.3% of the regions, whereas surgeons held the lead in 15.1% and radiologists in 13.6%. Referral regions where cardiologists dominated were more frequently located in the Midwest and South and had a higher number of operators performing carotid stenting per 100,000 Medicare enrollees. They also had significantly higher adjusted utilization rates than those where cardiologists performed 25% or fewer procedures (4.3 per 10,000 enrollees vs. 2.5 per 10,000 enrollees; P < 0.001).
After accounting for the number of operators, geographic region, and baseline rates of carotid endarterectomy in 2004, regions where cardiologists performed most CAS procedures still showed higher utilization rates relative to regions where most were performed by other specialists or a mix of specialists. There were no differences in risk-standardized outcomes, however.
Overutilization or Natural Development?
Although their data are limited, Dr. Nallamothu and colleagues say, they suspect that cardiologist-dominated areas are overutilizing CAS or that markets where surgeons or radiologists predominate have important barriers that limit access, leading to underutilization.
According to the study authors, the findings suggest “an important role for physician specialty in the choice to use carotid stenting.” They add that further research is needed “to better understand the specific nature of this relationship and whether multidisciplinary decision making by teams of specialists could optimize the use of this innovative technology.” The latter, they say, also may be a way to reduce unwanted variation in the adoption of CAS.
But Christopher J. White, MD, of the Ochsner Heart and Vascular Institute (New Orleans, LA), and president of the Society for Cardiovascular Angiography and Interventions, took issue with that stance.
“It’s unrealistic, and it’s a way of rationing health care,” Dr. White told TCTMD in a telephone interview. “You create bottlenecks where patients at risk for stroke have to sit and wait for approval.”
Dr. White also cautioned that the findings do not indicate that the CAS field is being overrun by cardiologists. “We were the first to use embolic protection devices and to become actively involved in research and clinical trials in this area,” he said. “In that sense, the dominance of cardiologists is appropriate to the way this technology was developed.”
During the study period, asymptomatic patients were actively being enrolled in trials like CREST, CABANA, and SAPPHIRE, he pointed out. Therefore, Dr. White said, there is no basis for concluding that cardiologists were selecting asymptomatic patients for CAS on their own without oversight.
Merely a ‘Snapshot’
According to William A. Gray, MD, of Columbia University Medical Center (New York, NY), the study primarily represents a “snapshot in time” that captures how CAS was being utilized around the country 4 to 6 years ago. As such, it may be somewhat dated. Still, he noted, it leaves open for speculation why cardiologists dominate CAS in some areas of the country and not others.
“Utilization can be looked at in several different ways, so it’s hard to tell exactly what these data mean,” he told TCTMD in a telephone interview. “There may be higher levels of surveillance in some areas and therefore higher treatment rates.” Another issue is that the data do not indicate the degree of stenosis, which may have affected how patients were referred, he added.
But Dr. Gray said the study does point out that the higher rates of CAS after coronary angiography or intervention within the cardiology group may be cause for concern.
“In my opinion, it’s not a good thing,” he said. “Engaging the carotids twice is really not something we should be doing and it should be avoided unless there is a clear indication of stenosis that would require going back and doing CAS.”
Source:
Nallamothu BK, Lu M, Rogers MAM, et al. Physician specialty and carotid stenting among elderly Medicare beneficiaries in the United States. Arch Intern Med. 2011;Epub ahead of print.
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L.A. McKeown is a Senior Medical Journalist for TCTMD, the Section Editor of CV Team Forum, and Senior Medical…
Read Full BioDisclosures
- Drs. Nallamothu, White, and Gray report no relevant conflicts of interest.
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