Article

Carotid endarterectomy was performed with lower stroke and death rates than carotid artery stenting in the United States in 2003 and 2004

Department of Surgery, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Journal of Vascular Surgery (Impact Factor: 3.02). 01/2008; 46(6):1112-1118. DOI: 10.1016/j.jvs.2007.08.030
Source: PubMed
ABSTRACT
Although carotid endarterectomy (CEA) is the gold standard for the treatment of carotid artery stenosis, the recent United States Food and Drug Administration approval of carotid artery stenting (CAS) may have led to its widespread use outside of clinical trials and registries. This study compared in-hospital postoperative stroke and mortality rates after CAS and CEA at the national level.
The Nationwide Inpatient Sample (NIS) was queried to identify all patient-discharges that occurred for revascularization of carotid artery stenosis. The International Classification of Diseases, 9th Revision, Clinical Modification procedure codes for CEA (38.12), CAS (00.63), and insertion of noncoronary stents (39.50, 39.90) were used in conjunction with the diagnostic codes for carotid artery stenosis, with (433.11) and without (433.10) stroke. Primary outcome measures included in-hospital postoperative stroke and death rates. Multivariate logistic regressions were performed to evaluate independent predictors of postoperative stroke and mortality. Adjustment was made for age, sex, medical comorbidities, admission diagnosis, procedure type, year, and hospital type.
During the calendar years 2003 and 2004, an estimated 259,080 carotid revascularization procedures were performed in the United States. CAS had a higher rate of in-hospital postoperative stroke (2.1% vs 0.88%, P < .0001) and higher postoperative mortality (1.3% vs 0.39%) than CEA. For asymptomatic patients (92%), the postoperative stroke rate was significantly higher for CAS than CEA (1.8% vs 0.86%, P < .0001), but the mortality rate was similar (0.44% vs 0.36%, P = .36). For symptomatic patients (8%), the rates for postoperative stroke (4.2% vs 1.1%, P < .0001) and mortality (7.5% vs 1.0%, P < .0001) were significantly higher after CAS. By multivariate regression, CAS was independently predictive of postoperative stroke (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.91 to 3.25). CAS was also associated with in-hospital postoperative mortality for asymptomatic (OR, 2.37; 95% CI, 1.46 to 3.84) and symptomatic (OR, 2.64; 95% CI, 1.89 to 3.69) patients.
As determined from a large representative national sample including the years 2003 and 2004, the in-hospital stroke rate after CAS for asymptomatic patients was twofold higher than after CEA. For symptomatic patients, the respective in-hospital stroke and mortality rates were fourfold and sevenfold higher. These unexpected results indicate that further randomized controlled trials with homogenous symptomatic and asymptomatic patient groups should be performed.

Full-text

Available from: Louis Messina
From the Society for Vascular Surgery
Carotid endarterectomy was performed with lower
stroke and death rates than carotid artery stenting
in the United States in 2003 and 2004
James T. McPhee, MD,
a
Joshua S. Hill, MD, MS,
b
Rocco G. Ciocca, MD,
b
Louis M. Messina, MD,
b
and Mohammad H. Eslami, MD,
b
Worcester, Mass
Objective: Although carotid endarterectomy (CEA) is the gold standard for the treatment of carotid artery stenosis, the
recent United States Food and Drug Administration approval of carotid artery stenting (CAS) may have led to its
widespread use outside of clinical trials and registries. This study compared in-hospital postoperative stroke and mortality
rates after CAS and CEA at the national level.
Methods: The Nationwide Inpatient Sample (NIS) was queried to identify all patient-discharges that occurred for
revascularization of carotid artery stenosis. The International Classification of Diseases, 9th Revision, Clinical Modification
procedure codes for CEA (38.12), CAS (00.63), and insertion of noncoronary stents (39.50, 39.90) were used in
conjunction with the diagnostic codes for carotid artery stenosis, with (433.11) and without (433.10) stroke. Primary
outcome measures included in-hospital postoperative stroke and death rates. Multivariate logistic regressions were
performed to evaluate independent predictors of postoperative stroke and mortality. Adjustment was made for age, sex,
medical comorbidities, admission diagnosis, procedure type, year, and hospital type.
Results: During the calendar years 2003 and 2004, an estimated 259,080 carotid revascularization procedures were
performed in the United States. CAS had a higher rate of in-hospital postoperative stroke (2.1% vs 0.88%, P < .0001) and
higher postoperative mortality (1.3% vs 0.39%) than CEA. For asymptomatic patients (92%), the postoperative stroke rate
was significantly higher for CAS than CEA (1.8% vs 0.86%, P < .0001), but the mortality rate was similar (0.44% vs
0.36%, P .36). For symptomatic patients (8%), the rates for postoperative stroke (4.2% vs 1.1%, P < .0001) and
mortality (7.5% vs 1.0%, P < .0001) were significantly higher after CAS. By multivariate regression, CAS was
independently predictive of postoperative stroke (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.91 to 3.25).
CAS was also associated with in-hospital postoperative mortality for asymptomatic (OR, 2.37; 95% CI, 1.46 to 3.84) and
symptomatic (OR, 2.64; 95% CI, 1.89 to 3.69) patients.
Conclusions: As determined from a large representative national sample including the years 2003 and 2004, the
in-hospital stroke rate after CAS for asymptomatic patients was twofold higher than after CEA. For symptomatic
patients, the respective in-hospital stroke and mortality rates were fourfold and sevenfold higher. These unexpected
results indicate that further randomized controlled trials with homogenous symptomatic and asymptomatic patient
groups should be performed. ( J Vasc Surg 2007;46:1112-8.)
Carotid artery stenting (CAS) was introduced in the
early 1990s as a potentially safer, less invasive alternative to
carotid endarterectomy (CEA) for the treatment of symp-
tomatic and asymptomatic patients with carotid artery ste-
nosis. Despite its approval by the United States Food and
Drug Administration in 2004 for use in symptomatic pa-
tients judged to be high risk for CEA,
1
the role of CAS in
the management of patients with carotid artery stenosis
remains disputed. Although CEA has been shown conclu-
sively to reduce the risk of stroke more than optimal med-
ical therapy alone for patients with symptomatic
2,3
and
asymptomatic
4,5
carotid artery stenosis, similar results from
prospective studies of CAS are lacking.
The minimally invasive nature of CAS makes it an
appealing treatment option for severe carotid artery steno-
sis. This fact may lead to increased usage over time
6
beyond
its currently approved indications specifically because of
varying interpretations of what constitutes “high” surgical
risk.
Because high-surgical-risk patients were excluded
from the landmark studies that showed CEA is superior
to optimal medical therapy alone for symptomatic
2
and
asymptomatic
5
carotid artery stenosis, controversy has
emerged about the appropriate intervention for this
high-risk patient population. This is partly due to the
results of certain industry-based trials,
7,8
the designs and
outcomes of which have been critiqued by others,
9-12
which have concluded that CAS is not an inferior modal-
ity to CEA in terms of composite stroke, death, or
myocardial infarction (MI) rates
7,8
despite recent pub-
licly funded randomized trials that have concluded the
contrary.
13,14
From Department of Surgery
a
and the Division of Vascular Surgery,
b
University of Massachusetts Medical School.
Competition of interest: none.
Podium presentation at the annual meeting of the Society for Vascular
Surgery, Baltimore, Md, Jun 7-10, 2007.
Additional material for this article may be found online at www.jvascsurg.org.
Reprint requests: Mohammad H. Eslami, MD, University of Massachusetts
Medical School, Department of Vascular Surgery, 55 Lake Ave N,
Worcester, MA 01655 (e-mail: eslamim@ummhc.org).
0741-5214/$32.00
Copyright © 2007 by The Society for Vascular Surgery.
doi:10.1016/j.jvs.2007.08.030
1112
Page 1
The Center for Medicare Services (CMS) recently ap-
proved reimbursement for carotid stenting in high-risk
symptomatic patients. Because of the conflicting results
from nonrandomized trials and the absence of a compara-
tive analysis at the national level of the morbidity and
mortality for CAS and CEA, it is difficult for physicians to
make definitive recommendations for their patients. For
this reason, we undertook a retrospective observational
population-based study to determine current in-hospital
postprocedural stroke and mortality rates after CAS and
CEA in symptomatic and asymptomatic patients in the
United States.
METHODS
To evaluate outcomes for CAS and CEA at the national
level, data were obtained from the Nationwide Inpatient
Sample (NIS) for the calendar years 2003 and 2004, the
most recent years available. The NIS is the most compre-
hensive database of its kind and includes 100% of abstracted
discharge data from a national survey of 20% of all nonfed-
eral acute-care hospitals in the United States.
15
These data
are linked to the American Hospital Association’s (AHA)
annual survey of hospitals by corresponding year to allow
analyses of hospital level factors such as bed size, teaching
status, and geographic location. The NIS provides a
weighting strategy to allow estimates to be made at the
national level. Each NIS sample hospital’s weight is equal to
the number of hospitals it represents during the year.
Because 20% of the AHA’s hospitals are sampled each year,
the given hospital’s weight is approximately five.
15
To
calculate national estimates, these sample weights are incor-
porated into the analyses, a technique described by other
authors.
16-18
All statistical analyses are based on these
survey weights; therefore, all data provided in the results
section represent weighted frequencies.
All CAS and CEA procedures performed during the
2-year period were identified by linking the International
Classification of Diseases Ninth Revision, Clinical Modifica-
tion (ICD-9CM)
19
procedural codes for CEA and CAS to
the appropriate primary diagnostic codes for carotid artery
stenosis with and without mention of stroke. Before 2004,
because the ICD-9CM procedure code specific to CAS
(00.63) did not exist, patients were coded under other less
specific procedural codes (Appendix, online only). Carotid
stent patients were identified by first querying the database
for the procedural codes for “angioplasty or atherectomy of
non-coronary vessel (39.50)” and “insertion of non-coronary
artery stent (39.90).” These less specific procedure codes
were then linked to only those patients with a principal
discharge diagnosis of carotid artery stenosis.
To more accurately analyze the primary outcome mea-
sures of postoperative stroke and mortality for the two
techniques, patients were classified as symptomatic or
asymptomatic. If a patient’s principal discharge diagnosis
was “carotid artery stenosis without mention of stroke”
with no accompanying secondary diagnoses for transient
ischemic attack (TIA), they were classified as asymptomatic.
If a patient’s principal discharge diagnosis was “carotid
artery stenosis with stroke” or if there was no mention of
stroke but a secondary diagnosis code included that for
TIA, patients were classified as symptomatic.
The primary outcome measures for this retrospective
study were in-hospital postoperative stroke and death. Post-
operative stroke was defined as carrying an ICD-9CM second-
ary diagnostic code of “post-operative stroke (997.02).” Post-
operative death was defined as any death during the same
hospital stay regardless of postoperative interval.
All statistical analyses were performed using the ad-
vanced survey procedures in the SAS 9.1 software (SAS
Institute, Cary, NC). Categoric variables were analyzed by
Rao-Scott
2
, and continuous variables were analyzed by
survey-weighted analysis of variance (ANOVA), with a
value of P .05 considered statistically significant.
Separate multivariate logistic regressions were per-
formed to determine which factors independently affected
postoperative stroke and mortality. The logistic regressions
were performed with adjustments made for the covariates
of patient age, gender, hospital teaching type, year of
procedure, presentation type (symptomatic vs asymptom-
atic), procedure type (CEA vs CAS), and payer status, as
well as the specific comorbid medical conditions of coro-
nary artery disease/previous MI, congestive heart failure,
valvular heart disease, diabetes mellitus, chronic lung dis-
ease, hypertension, renal failure, and obesity, with the use
of comorbidity software previously designed for use with
national databases.
20
An interaction term between the
treatment method (CAS vs CEA) and symptom status was
evaluated and found to be significant for postoperative
death; therefore, separate odds ratios (OR) and 95% confi-
dence intervals (CI) of postoperative death are provided
according to the presence or absence of symptoms.
RESULTS
Patient characteristics. In the United States during
the calendar years 2003 and 2004, an estimated 259,080
patient discharges occurred after CEA or CAS. Of these,
245,045 patients underwent CEA (94.6%) and 14,035
underwent CAS (5.4%). The mean age was 71.1 years
[standard error of the mean, 0.08], and 57% were men.
Almost all patients (92%) underwent treatment for asymp-
tomatic carotid artery stenoses. Of those that underwent
treatment for symptomatic stenoses, 62% were for symp-
toms of transient ischemic attack (TIA), and 38% were for
symptoms of stroke (Table I). The percentage of asymp-
tomatic and symptomatic patients treated at teaching vs
nonteaching hospitals was similar. Of those treated at
teaching hospitals, 8.1% were symptomatic compared with
7.9% at nonteaching hospitals (P .69).
Clinical presentation. On average, patients present-
ing with symptoms of TIA and stroke were older than the
asymptomatic patients (74.8 vs 71.6 years, P .0001). The
distribution of comorbid conditions was not uniform by
clinical presentation (Fig 1).
Univariate analysis of asymptomatic patient
characteristics. The characteristics of the patients under-
going CEA and CAS were comparable in terms of median
JOURNAL OF VASCULAR SURGERY
Volume 46, Number 6
McPhee et al 1113
Page 2
age (72 years for both) and certain comorbid conditions,
specifically, diabetes (P .62), coronary artery disease/
previous MI (P .94), valvular heart disease (P .44), and
obesity (P .15). Patients undergoing CEA had a higher
mean age (71.2 vs 70.5 years, P .0001) and a greater
prevalence of hypertension (P .011) and chronic lung
disease (P .0004). In contrast, patients undergoing CAS
had a higher prevalence of congestive heart failure (P
.0001) and renal failure (P .038) than the CEA group
and were more likely to be treated at a teaching hospital (P
.0001; Table II).
Univariate analysis of postoperative morbidity and
mortality. For asymptomatic patients with carotid artery
stenosis, the postoperative stroke rate was twofold higher
after CAS compared with CEA (1.8 vs 0.86%, P .0001),
but the crude in-hospital mortality rate after CEA and CAS
was similar (.34% vs 0.44%, P .36). The two procedures
were similar in terms of postoperative MI (2.0% vs 1.7%, P
.31; Table III).
Univariate analysis of symptomatic patient
characteristics. Patients undergoing CEA had a higher
mean age (70.1 vs 68.6 years, P .0001) and a greater
prevalence of the comorbid conditions of hypertension
(67.3% vs 60.3%, P .023) and chronic lung disease
(21.2% vs 14.1%, P .001). In contrast, the CAS patients
had a higher prevalence of renal failure (8.6% vs 2.4%, P
.0001). The two groups had similar rates of diabetes (P
.19), coronary artery disease (P .37), congestive heart
failure (P .37), valvular heart disease (P .93), and
obesity (P .35; Table II).
Univariate analysis of postoperative morbidity and
mortality. For symptomatic patients with carotid artery
stenosis, the postoperative stroke rate after CAS was nearly
fourfold higher than that for CEA (4.2% vs 1.1%, P
.0001). Similarly, the CAS patients had a sevenfold higher
postoperative mortality rate than the CEA patients (7.5% vs
1.0%, P .0001). The postoperative MI rate was similar for
CAS (2.2%) and CEA (2.0%; P .73; Table III).
Outcomes for octogenarians. By separate analysis,
the percentage of octogenarians in the two procedure
groups was similar. Of the open repair group, 19.7% of
patients were aged 80 year compared with 18.9% in the
endovascular group (P .42). The postoperative stroke
rate for octogenarians was increased in the endovascular
group compared with the open repair group (3.0% vs 1.0%,
P .0001), but the mortality rates were similar (1.2% vs
0.8%, P .19).
Multivariate analysis of postoperative stroke.
Carotid artery stenting had higher odds of being compli-
cated by postoperative stroke than did CEA (OR, 2.49;
95% CI 1.91 to 3.25). Other variables that independently
predicted stroke included older patient age group: 70 vs
60 years (OR, 1.56; 95% CI, 1.10 to 2.25), chronic lung
disease (OR, 1.31; 95 % CI, 1.07 to 1.61), congestive heart
failure (OR, 2.25; 95% CI, 1.70 to 2.98), the presence of
symptoms (OR, 1.47; 95% CI, 1.11 to 1.95), and postop-
erative MI (OR, 2.42; 95% CI, 1.52 to 3.84; Table IV,
Fig 2).
Multivariate analysis of postoperative mortality.
By multivariate logistic regression, which included adjust-
ments for multiple covariates, the performance of CAS was
independently predictive of increased postoperative mor-
Table I. Carotid revascularization patient characteristics,
2003 and 2004*
Factor Overall, No. (%) Mortality, % P
Patients, No. 259,080 (100) 0.44 NA
Age, y .0002
Mean (SEM) 71.1 (0.08)
Median (range) 72 (21-97)
60 32,287 (13) 0.29
60-69 73,001 (28) 0.31
70 153,792 (59) 0.53
Sex .52
Men 148,455 (57) 0.46
Women 110,395 (43) 0.42
Presentation type .0001
Asymptomatic 238,390 (92) 0.34
Symptomatic 20,690 (8) 1.6
TIA 12,900 (5) 0.43 .96
Stroke 8,003 (3) 3.4 .0001
Procedure type .0001
CEA 245,045 (95) 0.39
CAS 14,035 (5) 1.3
Hospital type .49
Nonteaching 142,352 (55) 0.42
Teaching 116,728 (45) 0.47
Payer .23
Private/Medicare 246,466 (95) 0.49
Medicaid/self-pay 12,370 (5) 0.29
CEA, Carotid endarterectomy; CAS, carotid artery stenting; NA, not appli-
cable; SEM, standard error of the mean; TIA, transient ischemic attack.
*Univariate analysis of overall in-patient mortality is included.
Fig 1. This bar graph compares the patient characteristics of
those presenting as asymptomatic (black) or symptomatic (grey)
carotid artery stenosis, 2003 and 2004. CEA, Carotid endarterec-
tomy; HTN, hypertension; DM, diabetes mellitus; COPD, chronic
obstructive pulmonary disease; CAD, coronary artery disease;
CHF, congestive heart failure; *P .05.
JOURNAL OF VASCULAR SURGERY
December 2007
1114 McPhee et al
Page 3
tality for asymptomatic patients (OR, 2.37; 95% CI 1.46 to
3.84) and symptomatic patients (OR, 2.64; 95% CI, 1.89
to 3.69; Table IV, Fig 3). Other independent predictors of
in-hospital mortality included presenting with symptoms of
TIA or stroke (OR, 4.01; 95% CI, 2.93 to 5.51), older
patient age (OR, 1.50; 95% CI, 1.09-2.06), a history of
congestive heart failure (OR, 3.74; 95% CI, 2.58 to 5.42),
obesity (OR, 2.23; 95% CI, 1.17 to 4.26), and renal failure
(OR, 2.50; 95% CI, 1.45 to 4.31). Similarly, certain post-
operative complications were strongly associated with in-
hospital mortality, including MI (OR, 4.61; 95% CI, 2.62
to 8.12) and stroke (OR, 31.0; 95% CI, 21.5 to 44.7).
DISCUSSION
This large population-based study has demonstrated
that during the calendar years 2003 and 2004, CEA con-
tinued to be associated with lower overall rates of postop-
erative stroke (0.88% vs 2.1%, P .0001) and mortality
(0.39% vs 1.3%, P .0001) than CAS. For asymptomatic
patients, the mortality rate for CEA and CAS was similar
(0.36% vs 0.44%, P .36); however, the postoperative
stroke rate of 1.8% for CAS was more than twofold higher
than the 0.86% rate for CEA (P .0001). Patients with
symptomatic stenoses who underwent CAS had a sevenfold
higher postoperative mortality rate (7.5% vs 1.0%, P
.0001) and nearly fourfold higher postoperative stroke rate
(4.2% vs 1.1%, P .0001) than those undergoing CEA.
These observations were confirmed by multivariate logistic
regression, which demonstrated that CAS was indepen-
dently predictive of postoperative mortality and stroke
(OR, about 2.4 for both), despite adjustment for comorbid
conditions, postoperative complications, and presentation
of “symptomatic” vs “asymptomatic” carotid artery ste-
nosis.
Studies with conflicting results have been published
comparing outcomes for CAS and CEA. The observations
from this administrative study compare favorably with
other population-based series limited to in-hospital values,
with similar CEA mortality and stroke rates
21
as well as an
Table II. Patient characteristics for revascularization of asymptomatic and symptomatic carotid artery stenosis
Factor Overall
Asymptomatic Symptomatic
CEA CAS P CEA CAS P
Characteristic
Overall No. 259,080 226,111 12,278 NA 18,933 1757 NA
Patient age, y
Mean (SEM) 71.1 (0.08) 71.2 (0.08) 70.5 (0.35) .0001 70.1 (0.19) 68.6 (0.71) .0001
Median (range) 72 (21-97) 72 (21-97) 72 (24-96) 71 (31-97) 70 (27-92)
Age groups, % .039 .20
60 12.5 11.9 13.9 17.5 20.7
60-69 28.2 28.2 29.2 26.8 28.2
70 59.4 59.9 56.9 55.7 51.1
Sex, % .045 .05
Men 57.4 56.9 59.3 61.1 55.8
Women 42.6 43.1 40.7 38.9 44.2
Comorbid conditions, %
Hypertension 70.2 70.8 66.7 .011 67.3 60.3 .023
Diabetes mellitus 25.1 25.4 25.8 .62 21.4 24.5 .19
Chronic lung disease 18.9 19.0 15.0 .0004 21.3 14.1 .001
CAD/MI 11.6 11.8 11.7 .94 9.8 8.4 .37
CHF 6.4 6.2 9.1 .0001 7.5 9.8 .13
Valvular disease 6.1 6.0 6.4 .44 6.9 6.8 .93
Renal failure 2.1 2.1 2.7 .038 2.4 8.6 .0001
Obesity 3.7 3.7 3.0 .15 4.4 3.5 .35
Hospital type, % .0001 .0001
Teaching 45 43.1 81.1 41.6 76.0
Nonteaching 55 56.9 18.9 58.4 24.0
Insurance type, % .002 .017
Private/Medicare 95.2 95.7 92.6 92.5 87.7
Medicaid/self-pay 4.8 4.3 7.4 7.5 12.3
CAD, Coronary artery disease; CAS, carotid artery stenting; CEA, carotid endarterectomy; CHF, congestive heart failure; MI, myocardial infarction; NA, not
applicable; SEM, standard error of the mean.
Table III. Surgical outcomes after carotid
endarterectomy and carotid artery stenting for
asymptomatic and symptomatic patients
Factor Overall
Asymptomatic Symptomatic
CEA CAS P CEA CAS P
Postoperative,
%
Mortality 0.44 0.34 0.44 .36 1.0 7.5 .0001
Stroke 0.95 0.86 1.8 .0001 1.1 4.2 .0001
MI 1.7 1.7 2.0 .31 2.0 2.2 .73
CAD, Coronary artery disease; CAS, carotid artery stenting; CEA, carotid
endarterectomy; MI, myocardial infarction.
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McPhee et al 1115
Page 4
observed increase in perioperative stroke (2.13% vs 1.28%)
and mortality (3% vs 0.5%) rates for CAS compared with
CEA at the national level.
6
Unlike the current work, these
prior studies did not separately analyze outcomes for symp-
tomatic and asymptomatic patient populations. They were
also limited to study years during which CAS was being
evaluated in clinical trials and therefore may have repre-
sented higher than expected stroke and mortality results
than contemporary CAS data.
The observations of the current work also agree with
those observed by the authors of the Endarterectomy ver-
sus Stenting in Patients with Symptomatic Severe Carotid
Stenosis (EVA-3S) study of 527 subjects, which found a
30-day risk of any stroke or death of 9.6% for CAS vs 3.9%
for CEA (relative risk, 2.5).
14
Of note, the EVA-3S study
was stopped early owing to concerns of safety and futility in
the CAS arm. The authors of a recent case–control series of
301 subjects similarly concluded that CAS was predictive of
30-day stroke compared with CEA (hazard ratio, 3.9; 95%
CI, 1.6 to 9.4, P .0002).
22
In contrast, several industry-sponsored registries, in-
cluding the ACCULINK for Revascularization of Carotids
in High-Risk patients (ARCHeR) trial and the Stenting and
Angioplasty with Protection in Patients at High Risk for
Endarterectomy (SAPPHIRE), have concluded that CAS is
a noninferior method to CEA in patients at high risk for
surgery.
7,8
These latter two studies have been criticized by
others because of their methodology, including the heter-
ogeneous population of symptomatic and asymptomatic
case-mix,
12
the power of the study,
10
and the validity of a
noninferiority study performed on nonrandomized data
using a historical control for the surgical arm.
12,23
Table IV. Multivariate analyses of in-hospital mortality
and postprocedural stroke for carotid revascularization,
2003 and 2004
Factor
In-hospital
mortality
Postprocedural
stroke
OR 95% CI OR 95% CI
Sex
Men (vs women) 1.08 .82-1.43 1.0 .83-1.20
Age group
70 (vs 60) 1.56 .93-2.62 1.56 1.10-2.25
70 (vs 60-69) 1.50 1.09-2.06 1.11 .90-1.35
Insurance type
Private (vs
Medicaid/self-
pay)
1.59 .63-4.0 .97 .62-1.53
Co-morbid conditions
(vs none)
Hypertension .66 .50-.89 .85 .70-1.04
Diabetes .70 .49-1.02 1.15 .94-1.41
Chronic lung disease 1.30 .93-1.84 1.31 1.07-1.61
CAD/MI .40 .22-.73 .64 .47-.86
Congestive heart
failure
3.74 2.58-5.42 2.25 1.70-2.98
Valvular heart
disease
.97 .59-1.58 .74 .50-1.10
Obesity 2.23 1.17-4.26 .97 .59-1.61
Renal failure 2.50 1.45-4.31 .83 .46-1.48
Presentation type
Symptomatic (vs
asymptomatic)
4.01 2.93-5.51 1.47 1.11-1.95
CAS vs CEA
Asymptomatic 2.37 1.46-3.84 2.49 1.91-3.25
Symptomatic 2.64 1.89-3.69
Hospital teaching
status
Nonteaching (vs
teaching)
.99 .68-1.28 1.17 .95-1.44
Post-op complications
(vs none)
MI 4.61 2.62-8.12 2.42 1.52-3.84
Stroke 31.0 21.5-44.7 NA NA
Acute renal failure 2.69 0.96-7.56 1.22 .44-3.34
CAD, Coronary artery disease; CAS, carotid artery stenting; CEA, carotid
endarterectomy; CI, confidence intervals; MI, myocardial infarction; NA,
not applicable; OR, odds ratio.
Fig 2. This chart demonstrates the odds ratios with 95% confi-
dence intervals for postoperative stroke after carotid artery revas-
cularization by carotid artery stenting (CAS) or carotid endarter-
ectomy (CEA). CAS was predictive of postoperative stroke by
logistic regression. COPD, Chronic obstructive pulmonary dis-
ease; CHF, congestive heart failure.
Fig 3. The odds ratios with 95% confidence intervals are pre-
sented for postoperative death after carotid artery revascularization
by carotid artery stenting (CAS) or carotid endarterectomy
(CEA). CAS was predictive of postoperative death by logistic
regression. CHF, Congestive heart failure.
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December 2007
1116 McPhee et al
Page 5
The ARCHeR investigators noted a 30-day risk of
stroke after CAS of 4.3% in their mostly (76%) asymptom-
atic patient population, which is similar to the 4.2% post-
operative stroke rate observed for symptomatic patients
undergoing CAS in the current work. The CAS-associated
stroke rate in the ARCHeR study is also substantially higher
than the CEA-associated stroke rate of 1.1% in this work
and others, which typically report values of 1.3% to
2.1%.
24,25
We note that these previous studies typically
report 30-day stroke and mortality rates, whereas the cur-
rent work is limited to in-hospital rates only, which may
reflect falsely lower rates by comparison. Further, the crite-
ria for what constitutes “high-risk” may vary widely based
on the methodology of these studies; likewise, individual
practitioners may have differing definitions of what consti-
tutes “high risk.”
The current data do not explain why symptomatic
patients undergoing CAS had significantly higher rates of
mortality and stroke than those undergoing CEA. This
study found that the CEA patients were older, and with the
exception of renal failure, had either similar (diabetes mel-
litus, coronary artery disease, congestive heart failure, val-
vular heart disease, obesity) or more severe (hypertension,
chronic obstructive pulmonary disease) comorbidity pro-
files than the CAS patients. Of note, characteristics such as
previous neck surgery, radiation, and carotid vessel mor-
phology, and the use of embolic protection device are not
available in this administrative data set.
The asymptomatic patients in this study who under-
went CEA and CAS were similar in age (median, 72 years)
and evenly matched for prevalence of significant medical
comorbid conditions (Table III). Despite this similarity,
overall the postoperative stroke rate was significantly
greater for the CAS group (1.8% vs 0.86%, P .0001). Of
importance, by multivariate logistic regression, which in-
cluded the variable for symptom status and comorbid con-
ditions, CAS remained independently predictive of postop-
erative stroke.
The limitations of analyses based on administrative data
sets such as the NIS in terms of miscoded and missing data
are well known.
26
The analysis in the current study found
the percentage of patients treated for asymptomatic carotid
artery stenosis (92%) was higher than expected, a fact that
warrants further investigation. A patient with a completed
stroke who was admitted without an active stroke could
conceivably have been misclassified into the asymptomatic
cohort. Likewise, if an in-hospital stroke after a procedure
was not properly coded as iatrogenic (997.02), the current
analysis could have potentially missed or misclassified a
percentage of postoperative strokes. It is, however, logical
that any potential misclassifications would occur without
bias toward any particular procedure group.
In addition, evaluating patient case-mix including the
severity of comorbid medical conditions and postoperative
complications is difficult to ascertain at the population
level.
27
Similarly unknown is the severity of complications
such as postoperative stroke and MI. To further compare
CEA and CAS patient groups, this clinical data would be
valuable. In this study, however, the variables of greatest
interest, including diagnosis type, procedure type per-
formed, and in-hospital mortality are reliably coded in the
NIS.
Before October 2004, no dedicated ICD-9CM proce-
dural code for CAS existed, and it was therefore previously
coded under other less-specific codes, which may lead to
some inaccuracy. The deidentification of patients in the
NIS precludes independent coding validation; however, by
linking the codes for endovascular angioplasty and stenting
with the appropriate diagnostic codes for carotid artery
stenosis (primary diagnosis only), the CAS patients should
be appropriately classified. This two-step technique to an-
alyze peripheral stenting procedures was previously de-
scribed by Nowygrod et al.
6
In addition, in-hospital outcomes, including mortality
and stroke, are somewhat limited measures of overall suc-
cess. Ideally, more long-term information such as 30-day
and 1-year follow-up would be used to compare the dura-
bility of one procedure vs another; however, they are not
available in this data set.
With surgical innovation, less invasive therapies with
potential benefits may lead to rapid diffusion of the tech-
nology. In the case of CAS, this issue is complicated by the
multidisciplinary backgrounds of the physicians performing
the procedure, some of whom would not otherwise be
providing care for patients with carotid artery occlusive
disease, as might be the case for cardiologists. Although
the technology for CAS will undoubtedly improve, and one
day it may replace CEA as the treatment of choice for some
patient populations, this paradigm shift should be predi-
cated on superior short- and long-term results of prospec-
tive randomized trials and not technical feasibility and
potential benefit.
CONCLUSION
During the period of this study, 2003 and 2004, within
the limitations of data obtained from administrative data
sets, CEA in the United States was performed with lower
risk of postoperative stroke and death than CAS in symp-
tomatic and asymptomatic patients with carotid artery ste-
nosis. These unexpected differences in observed outcomes
are not readily explained by differences in age or the prev-
alence of medical comorbidities. Further randomized con-
trolled studies with homogenous symptomatic and asymp-
tomatic cohorts should be performed to determine what
role CAS will play in the treatment of patients with carotid
artery stenosis.
We would like to thank Frank Zheng Zhou, MD, PhD,
for his assistance in the review of the statistical methods and
results reported in this manuscript.
AUTHOR CONTRIBUTIONS
Conception and design: JM, JH, LM, ME
Analysis and interpretation: JM, JH, RC, LM, ME
Data collection: JM, JH
Writing the article: JM
JOURNAL OF VASCULAR SURGERY
Volume 46, Number 6
McPhee et al 1117
Page 6
Critical revision of the article: LM, RC, ME
Final approval of the article: JM, ME, LM
Statistical analysis: JM, JH
Obtained funding: Not applicable
Overall responsibility: ME
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JOURNAL OF VASCULAR SURGERY
December 2007
1118 McPhee et al
Page 7
APPENDIX (online only). International Classification of Diseases, 9th Revision, Clinical Modification diagnostic and
procedural codes
Diagnosis Diagnostic code Procedure Procedural code
Carotid artery occlusion and stenosis
without mention of cerebral
infarction
433.10 Carotid endarterectomy 38.12
Carotid artery occlusion and
Stenosis with cerebral infarction
433.11 Angioplasty or atherectomy of noncoronary vessel 39.50
Multiple and bilateral carotid artery
occlusion and stenosis without
mention of cerebral infarction
433.30 Endovascular repair of vessel 39.7
Multiple and bilateral carotid artery
occlusion and stenosis with
cerebral infarction
433.31 Insertion of noncoronary artery stent or stents 39.90
Transient cerebral ischemia 435.9 Percutaneous insertion of carotid artery stent 00.63
Amaurosis fugax 362.34
JOURNAL OF VASCULAR SURGERY
Volume 46, Number 6
McPhee et al 1118.e1
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  • Source
    • "Patients were classified as symptomatic if they carried a diagnosis of amaurosis fugax (ICD-9CM 362.34 and 368.12), transient ischemic attack (TIA, ICD-9CM 435.9 and 781.4), or stroke (ICD9-CM 433.11, 433.31, 433.91, 434.01, 434.11, and 434.91). Patients were alternatively considered symptomatic if they carried a discharge diagnosis of carotid artery stenosis with infarction (ICD-9CM 433.11) or carotid artery stenosis without infarction (ICD-9CM 433.10) but with an accompanying diagnosis of TIA [12]. Patients were considered high risk if they met the criteria of Giles et al. [13]. "
    [Show abstract] [Hide abstract] ABSTRACT: Previous studies have demonstrated an adverse impact of African American race and Hispanic ethnicity on the outcomes of carotid endarterectomy (CEA), although little is known about the influence of race and ethnicity on the outcome of carotid angioplasty and stenting (CAS). The present study was undertaken to examine the influence of race and ethnicity on the outcomes of CEA and CAS in contemporary practice. The nationwide inpatient sample (2005-2008) was queried using International Classification of Diseases-9 codes for CEA and CAS in patients with carotid artery stenosis. The primary outcomes were postoperative death or stroke. Multivariate analysis was performed adjusting for age, gender, race, comorbidities, high-risk status, procedure type, symptomatic status, year, insurance type, and hospital characteristics. Overall, there were 347,450 CEAs and 47,385 CASs performed in the United States over the study period. After CEA, Hispanics had the greatest risk of mortality (P < 0.001), whereas black patients had the greatest risk of stroke (P = 0.02) compared with white patients on univariate analysis. On multivariable analysis, Hispanic ethnicity remained an independent risk factor for mortality after CEA (relative risk 2.40; P < 0.001), whereas the increased risk of stroke in black patients was no longer significant. After CAS, there were no racial or ethnic differences in mortality. On univariate analysis, the risk of stroke was greatest in black patients after CAS (P = 0.03). However, this was not significant on multivariable analysis. Hispanic ethnicity is an independent risk factor for mortality after CEA. While black patients had an increased risk of stroke after CEA and CAS, this was explained by factors other than race. Further studies are warranted to determine if Hispanic ethnicity remains an independent risk factor for mortality after discharge.
    Full-text · Article · Mar 2012 · Journal of Surgical Research
  • Source
    • "The EVA-3S trial has been criticized for the inexperience among its interventionalists and the lack of a standardized technique for PCA, but the flaws that some might find in this trial – the blend of community hospitals as well as referral centers, the mid-course changes to new or improved equipment, and the low procedural volumes or on-the-job training by more experienced colleagues – probably are ubiquitous and may make its results even more relevant to 'real world' practice [28] . The French trial was restricted to symptomatic patients, but another national dataset also showed that PCA/stenting was associated with higher risks for stroke or death than CEA in either symptomatic or asymptomatic patients in the United States during 2003 and 2004 [26]. ICSS An interim analysis of the International Carotid Stenting Study (ICSS), a large trial comprising 1713 symptomatic patients, has reported results at a maximum of 120 days following CEA or PCA (nearly all of the PCAs used stents and cerebral protection devices) [21]. "
    [Show abstract] [Hide abstract] ABSTRACT: Several large randomized clinical trials in North America and Europe concluded over a decade ago that carotid endarterectomy plus medical management was significantly better than medical management alone for stroke prevention in either symptomatic or asymptomatic patients with severe carotid stenosis. Percutaneous carotid angioplasty now represents yet another treatment option that currently appears to have a higher risk than endarterectomy in symptomatic patients as well as in those who are 70 years of age or older. For these reasons, there is a consensus that angioplasty should be used cautiously in such patients and probably remains most appropriate either in the context of ongoing randomized trials or for patients who are at a higher-than-average risk for conventional surgical treatment.
    Full-text · Article · Dec 2010 · F1000 Medicine Reports
  • Source
    • "The EVA-3S trial has been criticized for the inexperience among its interventionalists and the lack of a standardized technique for PCA, but the flaws that some might find in this trial -the mix of community hospitals as well as referral centers, the mid-course changes to new or improved equipment, the low procedural volumes or on-the-job training by more experienced colleagues -are ubiquitous and may make its results more relevant to 'real world' practice [21]. The French trial was limited to symptomatic patients, but another national dataset also has shown that PCA/stenting was associated with higher risks for stroke or death than CEA in both symptomatic and asymptomatic patients in the United States during 2003 and 2004 [19]. "
    [Show abstract] [Hide abstract] ABSTRACT: Several large randomized clinical trials in North America and Europe concluded over a decade ago that carotid endarterectomy plus medical management was significantly better than medical management alone for stroke prevention in either symptomatic or asymptomatic patients with severe carotid stenosis. Percutaneous carotid angioplasty now represents another treatment option that currently seems most appropriate either in the context of prospectively randomized trials or for patients who are at a higher than average risk for conventional surgical treatment.
    Full-text · Article · Feb 2009 · F1000 Medicine Reports
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