From the New England Society for Vascular Surgery
National trends in utilization and postprocedure
outcomes for carotid artery revascularization
2005 to 2007
Mohammad H. Eslami, MD,aJames T. McPhee, MD,bJessica P. Simons, MD,aAndres Schanzer, MD,a
and Louis M. Messina, MD,aWorcester, Mass
Objective: This study compared, at a national level, trends in utilization, mortality, and stroke after carotid angioplasty
and stenting (CAS) and carotid endarterectomy (CEA) from 2005 to 2007.
Methods: The Nationwide Inpatient Sample (NIS) was queried for patient discharges with International Classification of
Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes for CAS and CEA. The primary outcomes were
in-hospital mortality, stroke, hospital charges, and discharge disposition. Subgroup analyses were performed to evaluate
these outcomes by neurologic presentation using ?2and multivariable logistic regression.
Results: Of the 404,256 discharges for carotid revascularization, CAS utilization was 66% higher in 2006 than in 2005
(9.3% vs 14%, P ? .0004). Crude mortality, stroke, and median charges remained higher for CAS than for CEA; discharge
to home was more common after CEA. Results improved from 2005 to 2007. By logistic regression of the total cohort
from 2005 to 2006, CAS was independently predictive of mortality (odds ratio [OR], 1.47; 95% confidence interval [CI],
1.08-2.00; P < .0001). Independent predictors of stroke included CAS (OR, 1.43; 95% CI, 1.18-1.73; P < .0001) and
symptomatic disease (OR, 2.4; 95% CI, 2.06-2.93;P < .0001). Among subgroups based on neurological presentation,
regression showed that CAS significantly increased the odds of stroke in asymptomatic patients (OR, 1.6; 95% CI,
1.2-2.0; P ? .0003). Among symptomatic patients, CAS increased the odds of in-hospital death (OR, 3.0; 95% CI,
1.7-5.1, P < .0001) and trended toward significance for stroke (OR, 1.7; 95% CI, 1.0-2.8; P ? .0569).
Conclusion: Utilization of CAS has increased from the years 2005 to 2007 with some improvements in the outcome.
Despite improvements in outcome, resource utilization remains significantly higher for CAS than CEA. (J Vasc Surg
Since the endovascular technique was first described in
the early 1990s,1,2proponents of carotid artery stenting
(CAS) have cited its less invasive nature as an alternative to
without a clear definition of such patients. Several studies
have compared the postprocedure results of CAS and ca-
rotid endarterectomy (CEA) in both symptomatic and
asymptomatic patients.3-7Results are conflicting and de-
bate persists about the role of CAS in the treatment of
carotid artery stenosis. Previous work by our group com-
paring CAS with CEA shortly after CAS approval by the
Food and Drug Administration (FDA) in March of 2004,
demonstrated higher morbidity and mortality associated
with CAS.8,9However, discrepancies in the risk-adjusted
clinical outcomes have not tempered enthusiasm for this
procedure which is performed often outside of Center for
Medicare and Medicaid Services (CMS) guidelines8,9and
by different specialties.10
In addition to the risk-adjusted clinical outcome dis-
crepancies between the two procedures, cost and resource
utilization must be compared. Two procedures are consid-
ered to achieve clinical equipoise once outcomes, resource
utilizations, and procedural costs are similar. Previous stud-
ies have demonstrated that CAS may be associated with
increased charges when compared directly to CEA.11-13
Using a Markov type decision model, studies14,15have
suggested CAS to be more costly given the current clinical
outcomes. At the national level, we have shown that CAS
was associated with higher cost utilization in 2005, the first
year after this procedure was approved.9However, as pro-
viders gain familiarity with new techniques, results often
improve and this may lead to the CAS becoming more
The purpose of this study was to perform a national,
population-based, observational study to evaluate the out-
comes and resource utilization for CAS and CEA during
the years 2005 to 2007 using the specific International
Classification of Diseases Ninth Revision, Clinical Modifica-
tion (ICD-9-CM) code for CAS that became available in
2004 after FDA approval. We sought to compare trends in
the most recent available data, examining whether utiliza-
tion of CAS has increased since US FDA approval. We also
evaluated whether such an increase in utilization had led to
From theaDivision of Vascular and Endovascular Surgery andbDepartment
of General Surgery, University of Massachusetts Medical School, Worces-
Competition of interest: none.
Presented at the Thirty-sixth Annual Meeting of the New England Society
for Vascular Surgery, Boston, Mass, October 2-4, 2009.
Reprint requests: Mohammad H. Eslami, MD, University of Massachusetts
Medical School, Division of Vascular and Endovascular Surgery, 55 Lake
Avenue North, Worcester, MA 01655 (e-mail: EslamiM@ummhc.org).
The editors and reviewers of this article have no relevant financial relationships
to disclose per the JVS policy that requires reviewers to decline review of any
manuscript for which they may have a competition of interest.
Copyright © 2011 by the Society for Vascular Surgery.
improved outcomes or decreased resource utilization. The
postprocedure outcomes (death and stroke) and resource
utilization may ultimately determine the best treatment for
patients with carotid artery stenosis.
The Nationwide Inpatient Sample (NIS) was queried
for calendar years 2005 to 2007, the most recent available
data, for patient discharges after carotid revascularization.
This represents a stratified sample of 20% of nonfederal US
community hospitals from participating states, containing
information for approximately 7 million hospital dis-
methodology is similar to that used in our previously pub-
lished studies.8,9Briefly, the database was first queried to
identify all patients undergoing carotid revascularization for
carotid artery stenosis using ICD-9-CM codes for either CAS
(ICD-9-CM procedure code 00.63) or CEA (38.12)17and
of neurological symptoms (433.11).18If a patients’ dis-
charge diagnosis (diagnostic fields 1-15) was “carotid ar-
tery without mention of stroke” with no accompanying
secondary diagnosis for transient ischemic attack (TIA),
they were classified as “asymptomatic.” Patients were con-
sidered symptomatic if they had either a secondary diagno-
sis of stroke or TIA. Patients who had a combined CAS and
CEA codes, less than 1% of patients, were excluded from
this study to allow for homogeneity of the cohorts and
better comparison between the two groups.
Demographic information including age at admission,
gender, and race was collected. Race information was ex-
cluded from all explanatory analyses because of the high
rate (?20%) of missing values. Records for patients’ age
?18 or ?100 years old were also excluded. Comorbid
conditions were identified using the Elixhauser method.19
The identified cohort of patient discharges was ana-
lyzed for codes for in-hospital death and postprocedure
stroke, the primary outcome measures of this analysis.
assigned as death due to any cause at any point in time
during the index hospitalization. Postprocedure stroke was
identified among secondary discharge diagnoses using a
specific ICD-9-CM code (997.02) for this complication.18
The secondary outcome measures for this study included
resource utilization, namely length of stay (LOS) during
the index hospital admission stay, total hospital charges,
and discharge disposition similar to our prior publication.9
Detailed specific procedure cost information is lacking in
the NIS, therefore, the total hospital charges were used as a
surrogate for cost information. Discharges of the surviving
patients during the index admissions were dichotomized
into either discharge to home (with or without services), or
“other” that included discharges to another facility, includ-
ing a skilled nursing facility or nursing home.
To comment on trends in both utilization of CAS for
carotid artery revascularization and in outcomes after CAS,
we compared the primary and secondary outcomes be-
and specialty hospitals
tween CAS and CEA during the first complete 3 calendar
years (2005-2007), which is the most currently available
Statistical analysis. Univariate analyses according to
procedure type and year were conducted using Rao-Scott
for categorical data and survey-weighted analysis of vari-
ance for continuous data for all specified end points, with
P ? .05 considered statistically significant. As previously
described, the Elixhauser comorbidity software was used to
identify patient comorbidities for univariate and multivari-
ate analyses.19This is a very powerful software tool that
allows for accurate identification of pre-existing medical
comorbidities. Admittedly, comprehensible risk stratifica-
tion is not possible, as we have previously noted.8,9Sub-
group analyses according to neurologic presentation were
carried out in an analogous fashion.
mine which factors were independently predictive of post-
operative stroke and death. Covariates controlled for in this
model included gender, age, comorbid conditions, presen-
tation type, procedure type, and year of the procedure,
hospital teaching status, and hospital bed size. Predictors of
in-hospital death were evaluated in an analogous fashion,
but with presence of a postprocedure stroke used as an
additional covariate in these models. Statistical analyses
were performed with advanced survey procedures when-
ever possible, using SAS (v9.1, Cary, NC). Data are pre-
sented in their weighted frequencies, as previously de-
scribed, and the missing data were excluded by SAS from
Patient discharge characteristics. From the years
2005 to 2007, an estimated 404,256 patient discharges
after carotid revascularization occurred in the United
States. Each year contributed equally to the patient sample.
The majority of carotid revascularization was performed by
CEA (88.6% vs CAS, 11.4%). Overall, 54% of these revas-
cularizations were performed at non-teaching institutions
(P ? .05). A proportionately higher percentage of CAS
procedures were performed at the teaching hospitals com-
pared to the non-teaching institutions (60.7% vs 39.3%;
P ? .001). Large hospitals, as defined by the American
Hospital Association’s annual survey of hospitals, per-
formed the majority of carotid revascularizations but no
statistically significant difference across the procedure type
was noted among the large hospitals; 73.3% of CAS proce-
dures and 67.7% of CEA procedures (P ? .18) were per-
formed at these hospitals. There was an initial significant
increase for CAS utilization for carotid revascularization
comparing 2005 to 2006 (9.3% vs 14% absolute values of
the total procedures; P ? .004) but no such increase was
noted from 2006 to 2007 (Fig 1). Detailed characteristics
of the cohort can be found in Table I. Asymptomatic
disease was far more common, comprising 91.8% of the
cohort. Median age and age distribution was similar be-
tween the two procedures with an equal number of octo-
genarians represented in both groups. Overall, 57.8%
JOURNAL OF VASCULAR SURGERY
308 Eslami et al
Conception and design: ME
Analysis and interpretation: JM, JS
Data collection: JM, JS
Writing the article: ME, JM
Critical revision of the article: LM, AS
Final approval of the article: ME
Statistical analysis: JM
Obtained funding: Not applicable
Overall responsibility: ME
1. Marks MP, Dake MD, Steinberg GK, Norbash AM, Lane B. Stent
placement for arterial and venous cerebrovascular disease: preliminary
experience. Radiology 1994;191:441-6.
2. Yadav JS, Roubin GS, Iyer S, Vitek J, King P, Jordan WD, Fisher WS.
Elective stenting of the extracranial carotid arteries. Circulation 1997;
3. Yadav JS, Wholey MH, Kuntz RE, Fayad P, Katzen VT, Mishkel GJ, et
al. Protected carotid-artery stenting versus endarterectomy in high-risk
patients. N Engl J Med 2004;351:1493-501.
4. Golledge J, Mitchell A, Greenhalgh RM, Davies AH. Systematic com-
parison of the early outcome of angioplasty and endarterectomy for
symptomatic carotid artery disease. Stroke 2000;31:1439-43.
5. SPACE Colaborative Group, Ringleb PA, Allenberg J, Brückmann H,
Eckstein HH, Fraedrich G, et al. 30 day results from the SPACE trial of
stent-protected angioplasty versus carotid endarterectomy in symptomatic
patients: a randomised non-inferiority trial. Lancet 2006;368:1239-47.
6. [No authors listed] Endovascular versus surgical treatment in patients
with carotid stenosis in the Carotid and Vertebral Artery Transluminal
Angioplasty Study (CAVATAS): a randomised trial. Lancet 2001;357:
7. Naylor AR, Bolia A, Abbott RJ, Pye IF, Smith J, Lennard N, et al.
Randomized study of carotid angioplasty and stenting versus carotid
endarterectomy: a stopped trial. J Vasc Surg 1998;28:326-34.
8. McPhee JT, Hill JS, Ciocca RG, Messina LM, Eslami MH. Carotid
endarterectomy was performed with lower stroke and death rates than
carotid artery stenting in the United States in 2003 and 2004. J Vasc
9. McPhee JT, Schanzer A, Messina LM, Eslami MH. Carotid artery
J Vasc Surg 2008;48:1442-50.
10. Steppacher R, Csikesz N, Eslami M, Arous E, Messina L, Schanzer A.
and Florida (2005-2006): procedure indication, stroke rate, and mor-
tality rate are equivalent for vascular surgeons and non-vascular sur-
geons. J Vasc Surg 2009;49:1379-85; discussion 1385-6.
11. Park B, Mavanur A, Dahn M, Menzoian J. Clinical outcomes and cost
comparison of carotid artery angioplasty with stenting versus carotid
endarterectomy. J Vasc Surg 2006;44:270-6.
12. Pawaskar M, Satiani B, Balkrishnan R, Starr JE. Economic evaluation of
carotid artery stenting versus carotid endarterectomy for the treatment
of carotid artery stenosis. J Am Coll Surg 2007;205:413-9.
13. Jordan WD Jr, Roye GD, Fisher WS 3rd, Redden D, McDowell HA. A
cost comparison of balloon angioplasty and stenting versus endarterec-
tomy for the treatment of carotid artery stenosis. J Vasc Surg 1998;27:
16-22; discussion 22-4.
14. Kilaru S, Korn P, Kasirajan K, Lee TY, Beavers FP, Lyon RT, et al. Is
carotid angioplasty and stenting more cost effective than carotid end-
arterectomy? J Vasc Surg 2003;37:331-9.
15. Janssen MP, de Borst GJ, Mali WP, Kappelle LJ, Moll FL, Ackerstaff
RG, et al. Carotid stenting versus carotid endarterectomy: evidence
basis and cost implications. Eur J Vasc Endovasc Surg 2008;36:258-64;
16. Nationwide Inpatient Sample (NIS). Overview available at http://
www.hcup-us.ahrq.gov/nisoverview.jsp. Accessed October 10, 2009.
17. Centers for Medicare and Medicaid Service. Updates and Revisions to
ICD-9-CM Procedure Codes (Addendum). http://www.cms.hhs.
pdf. Accessed October 10, 2009.
18. US Department of Health and Human Services, International Classifi-
cation of Diseases, Ninth Revision, Clinical Modification. US Govern-
ment Printing Office, Washington, DC; 1998.
19. Elixhauser A, Steiner C, Harris DR, Coffey RM. Comorbidity measures
for use with administrative data. Med Care 1998;36:8-27.
20. Kotwall CA, Maxwell JG, Brinker CC, Koch GG, Covington DL.
National estimates of mortality rates for radical pancreaticoduodenec-
tomy in 25,000 patients. Ann Surg Oncol 2002;9:847-54.
21. Hobson RW 2nd, Howard VJ, Roubin GS, Brott TG, Ferguson RD,
Popma JJ, et al. Carotid artery stenting is associated with increased
complications in octogenarians: 30-day stroke and death rates in the
CREST lead-in phase. J Vasc Surg 2004;40:1106-11.
22. Mas JL, Chatellier G, Beyssen B, Branchereau A, Moulin T, Becquemin
JP, et al. Endarterectomy versus stenting in patients with symptomatic
severe carotid stenosis. N Engl J Med 2006;355:1660-71.
23. Gray WA, Hopkins LN, Yadav S, Davis T, Wholey M, Atkinson R, et al.
Protected carotid stenting in high-surgical-risk patients: the ARCHeR
results. J Vasc Surg 2006;44:258-68.
H, Eckstein HH, Fraedrich G. 30 day results from the SPACE trial of
stent-protected angioplasty versus carotid endarterectomy in symptom-
atic patients: a randomised non-inferiority trial. Lancet 2006;368:
25. Goodney PP, Travis LL, Malenka D, Bronner KK, Lucas FL, Cronen-
wett JL, et al. Regional variation in carotid artery stenting and endar-
terectomy in the Medicare population. Circ Cardiovasc Qual Outcomes
26. van der Vaart MG, Meerwaldt R, Reijnen MM, Tio RA, Zeebregts CJ.
Endarterectomy or carotid artery stenting: the quest continues. Am J
27. Brott TG, Hobson RW 2nd, Howard G, Roubin GS, Clark WM,
Brooks W, et al. Stenting versus endarterectomy for treatment of
carotid-artery stenosis. N Engl J Med 2010;363:11-23.
28. White RA, Sicard GA, Zwolak RM, Sidawy AN, Schermerhorn ML,
Shackelton RJ, et al. Society of Vascular Surgery Vascular Registry com-
parison of carotid artery stenting outcomes for atherosclerotic vs nonath-
erosclerotic carotid artery disease. J Vasc Surg 2010;51:1116-23.
29. Sayeed S, Stanziale SF, Wholey MH, Makaroun MS. Angiographic
lesion characteristics can predict adverse outcomes after carotid artery
stenting. J Vasc Surg 2008;47:81-7.
30. Tseng JF, Pisters PW, Lee JE, Wang H, Gomez HF, Sun CC, et al. The
learning curve in pancreatic surgery. Surgery 2007;141:694-701.
31. Iezzoni LI, Foley SM, Daley J, Hughes J, Fisher ES, Heeren T.
Comorbidities, complications, and coding bias. Does the number of
diagnosis codes matter in predicting in-hospital mortality? JAMA 1992;
Submitted Apr 23, 2010; accepted Aug 26, 2010.
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