Geographic Variation and Trends in Carotid Imaging
Among Medicare Beneficiaries, 2001 to 2006
Lesley H. Curtis, PhD; Melissa A. Greiner, MS; Manesh R. Patel, MD; Pamela W. Duncan, PhD, PT;
Kevin A. Schulman, MD; David B. Matchar, MD
Background—Diagnostic imaging among Medicare beneficiaries is an important contributor to rising health care costs. We
examined temporal trends and geographic variation in the use of carotid ultrasound, carotid magnetic resonance
angiography (MRA), and carotid x-ray angiography.
Methods and Results—Analysis of a 5% national sample of claims from the Centers for Medicare and Medicaid Services
for 1999 through 2006. Patients were 65 years or older and underwent carotid ultrasound, carotid MRA, carotid x-ray
angiography, or a carotid intervention. The main outcome measures were annual age-adjusted rates of carotid imaging
and interventions and factors associated with the use of carotid imaging. Rates of imaging increased by 27%, from 98.2
per 1000 person-years in 2001 to 124.3 per 1000 in 2006. Rates of carotid ultrasound increased by 23%, and rates of
MRA increased by 66%. Carotid intervention rates decreased from 3.6 per 1000 person-years in 2001 to 3.1 per 1000
person-years in 2006. In 2006, rates of carotid ultrasound were lowest in the New England, Mountain, and West North
Central regions and highest in the Middle Atlantic and South Atlantic regions. Regional differences persisted after
adjustment for patient demographic characteristics, history of vascular disease and other comorbid conditions, and study
Conclusions—From 2001 through 2006, there was substantial growth and variation in the use of carotid imaging, including
a marked increase in the use of MRA, and a decrease in the overall rate of carotid intervention. (Circ Cardiovasc Qual
Key Words: carotid arteries ? diagnosis ? imaging ? stenosis
strokes result from carotid atherosclerosis.1Although athero-
sclerosis is common among older persons and increases with
age,2the prevalence of clinically important stenosis is low.
Routine screening generally is not recommended in asymp-
tomatic patients, because fewer than 1% are likely to have
clinically important atherosclerosis3–5and because the risk of
complications outweighs the benefits.6,7Nevertheless, the
prevalence of clinically important carotid stenosis is higher
among older patients with a history of peripheral vascular
disease or coronary stenosis, so diagnostic imaging in these
patients may be warranted.8Other common indications for
carotid imaging include hemispheric stroke, transient ische-
mic attack with localizing symptoms or findings including
amaurosis fugax, and follow-up of previously diagnosed
Common methods of evaluating carotid stenosis include
ultrasound, magnetic resonance angiography (MRA), and
x-ray angiography (including noninvasive computed to-
pproximately 780 000 people in the United States each
year have a new or recurrent stroke, and 10% of these
mography [CT] angiography and invasive angiography).
The benchmark method, digital subtraction cerebral an-
giography, is associated with some risk. Noninvasive tests
such as ultrasound and MRA carry less risk but may not be
as accurate and, in the case of MRA, are more expensive.
Since 2000, diagnostic imaging among Medicare beneficia-
ries has increased 5.9% per year, and expenditures for diagnostic
imaging have increased more than 11% per year.9Together,
nonechocardiography ultrasound, CT, and magnetic resonance
imaging (MRI) accounted for almost 50% of imaging expendi-
tures under the Medicare physician fee schedule in 2005.10
Diagnostic imaging among Medicare beneficiaries is an impor-
tant contributor to rising health care costs.11However, little is
known about recent trends in the use of carotid imaging.
Moreover, evidence of benefit for asymptomatic patients with
carotid stenosis12and the recent introduction of alternative
revascularization methods such as carotid stenting may have
altered the thresholds for the appropriateness of diagnostic
imaging. Therefore, we examined trends and geographic varia-
tion in the use of carotid imaging from 2001 through 2006.
Received March 1, 2010; accepted August 31, 2010.
From the Duke Clinical Research Institute (L.H.C., M.A.G., M.R.P., K.A.S.), Departments of Medicine (L.H.C., M.R.P., K.A.S., D.B.M.) and
Community and Family Medicine (P.W.D.), and Center for Clinical Health Policy Research (L.H.C., P.W.D., K.A.S., D.B.M.), Duke University School
of Medicine, Durham, NC; and Program in Health Services Research (D.B.M.), Duke-NUS Graduate Medical School Singapore.
Correspondence to Lesley H. Curtis, PhD, Duke Clinical Research Institute, PO Box 17969, Durham, NC 27715. E-mail firstname.lastname@example.org
© 2010 American Heart Association, Inc.
Circ Cardiovasc Qual Outcomes is available at http://circoutcomes.ahajournals.org DOI: 10.1161/CIRCOUTCOMES.110.950279
19. Berens ES, Kouchoukos NT, Murphy SF, Wareing TH. Preoperative
carotid artery screening in elderly patients undergoing cardiac surgery.
J Vasc Surg. 1992;15:313–321.
20. Salasidis GC, Latter DA, Steinmetz OK, Blair JF, Graham AM.
Carotid artery duplex scanning in preoperative assessment for
coronary artery revascularization: the association between peripheral
vascular disease, carotid artery stenosis, and stroke. J Vasc Surg.
21. Obuchowski NA, Modic MT, Magdinec M, Masaryk TJ. Assessment of
the efficacy of noninvasive screening for patients with asymptomatic
neck bruits. Stroke. 1997;28:1330–1339.
22. Fabris F, Zanocchi M, Bo M, Fonte G, Poli L, Bergoglio I, Ferrario E,
Pernigotti L. Carotid plaque, aging, and risk factors: a study of 457
subjects. Stroke. 1994;25:1133–1140.
23. Sutton-Tyrrell K, Alcorn HG, Wolfson SK Jr, Kelsey SF, Kuller LH.
Predictors of carotid stenosis in older adults with and without isolated
systolic hypertension. Stroke. 1993;24:355–361.
24. Oddone EZ, Horner RD, Sloane R, McIntyre L, Ward A, Whittle J,
Passman LJ, Kroupa L, Heaney R, Diem S, Matchar D. Race, presenting
signs and symptoms, use of carotid artery imaging, and appropriateness of
carotid endarterectomy. Stroke. 1999;30:1350–1356.
25. Goldstein LB, Matchar DB, Hoff-Lindquist J, Samsa GP, Horner RD.
Veterans Administration Acute Stroke (VASt) Study: lack of race/
ethnic-based differences in utilization of stroke-related procedures or
services. Stroke. 2003;34:999–1004.
26. Patel MR, Spertus JA, Brindis RG, Hendel RC, Douglas PS, Peterson ED,
Wolk MJ, Allen JM, Raskin IE; American College of Cardiology Foun-
dation. ACCF proposed method for evaluating the appropriateness of
cardiovascular imaging. J Am Coll Cardiol. 2005;46:1606–1613.
606 Circ Cardiovasc Qual Outcomes