Additional Stroke Related and Non Stroke
Additional Stroke-Related and Non–Stroke-Related
Cardiovascular Costs and Hospitalizations in Managed-Care
Patients After Ischemic Stroke
Craig S. Roberts, PharmD, MPA; Philip B. Gorelick, MD, MPH; Xin Ye, PhD;
Carolyn Harley, PhD; George A. Goldberg, MD
Background and Purpose—Prior stroke confers an increased risk of future cardiovascular events. Because the incremental
economic impact of this added risk is unknown, we assessed the additional cardiovascular costs and hospitalizations
associated with ischemic stroke.
Methods—Patients hospitalized for ischemic stroke during 2002 to 2005 were identified from a large US managed-care plan and
matched to control patients hospitalized for a noncardiovascular acute event. Cumulative stroke-related and non–strokerelated cardiovascular medical costs were determined for each group. Stroke and nonstroke cardiovascular hospitalization
rates were calculated with the Kaplan–Meier method; risk of hospitalization was estimated with a Cox regression model.
Results—Stroke patients and matched controls (N⫽11 883) were identified (mean age ⬇58 years; 47.8% female).
Compared with controls, patients hospitalized for ischemic stroke had higher stroke and nonstroke cardiovascular
medical costs at 6 months (stroke: $1756 vs $50, P⬍0.01; nonstroke cardiovascular: $1437 vs $658, P⬍0.01) and 12
months (stroke: $2109 vs $68, P⬍0.01; nonstroke cardiovascular: $2203 vs $1167, P⬍0.01) of follow-up. Among
stroke patients, cumulative stroke and nonstroke cardiovascular hospitalization rates were 9.06% and 5.63% at 6 months,
respectively, and 21.09% and 22.05% at 36 months, respectively. Stroke patients were at significantly increased risk of
repeat stroke hospitalization (hazard ratio⫽12.55; 95% CI, 10.50 to 15.01) and nonstroke cardiovascular hospitalization
(hazard ratio⫽1.95; 95% CI, 1.77 to 2.14).
Conclusions—After ischemic stroke, patients have significantly greater stroke and nonstroke cardiovascular costs and
hospitalizations than do matched controls. Attention to total cardiovascular risk reduction in this population could
potentially reduce downstream costs. (Stroke. 2009;40:1425-1432.)
Key Words: stroke 䡲 health care costs 䡲 hospitalization 䡲 risk factors 䡲 managed care
S
troke represents a major public health problem in the
United States, where it is the third leading cause of
mortality, accounting for ⬎150 000 deaths annually, and is
one of the leading causes of long-term adult disability.1 There
are an estimated 5.8 million survivors of stroke in the United
States alone, and up to one third of stroke patients may be left
permanently disabled or require several months of institutional care after an attack.1
Patients with prior stroke are at increased risk of future
cerebrovascular events: of the ⬇780 000 strokes occurring in
the United States each year, ⬇180 000 are recurrent attacks.1
Ischemic strokes account for 87% of all strokes.1 Although a
repeat stroke is the most common secondary ischemic event
in the years after an ischemic stroke,2– 4 these patients are also
at increased risk of coronary events such as myocardial
infarction (MI) and cardiac death.5–7 The observation that
ischemic stroke may predict future cardiac events is indica-
tive of the shared risk factors and pathophysiologic mechanisms underlying these events and the systemic nature of
atherosclerotic vascular disease.
Owing to the high level of morbidity associated with
stroke, the economic burden of this disease is substantial. For
2008, it is estimated that stroke will cost the US economy
$65.5 billion in health care services, medications, and lost
productivity.1 Few studies have estimated the incremental
health care costs and resource utilization associated with
ischemic stroke, particularly those costs and hospitalizations
that arise from non–stroke-related cardiovascular events
(eg, MI, angina, revascularization, and heart failure) in the
poststroke follow-up period. Therefore, using claims data
from a large US managed-care health plan for 2002 to
2005, we assessed the long-term stroke-related and non–
stroke-related cardiovascular costs and hospitalization risk
in patients hospitalized for ischemic stroke compared with
Received August 12, 2008; accepted September 12, 2008.
From Pfizer Inc (C.S.R.), New York, NY; the University of Illinois at Chicago (P.B.G.); and i3 Innovus, Eden Prairie, Minn (X.Y., C.H.), and Santa
Monica, Calif (G.A.G.).
Correspondence to Craig S. Roberts, PharmD, MPA, Global Outcomes Research, Pfizer Inc, 235 East 42nd St, New York, NY 10017. E-mail
Craig.Roberts@pfizer.com
© 2009 American Heart Association, Inc.
Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.108.534354
1425
Downloaded from http://stroke.ahajournals.org/
by guest on July 4, 2015
1426
Stroke
April 2009
Stroke Cohort
Control Cohort
Patients hospitalized for ischemic stroke,
Jan 1, 2002–Dec 31, 2005
n=45,163
Patients hospitalized for a non-stroke event,
Jan 1, 2002–Dec 31, 2005
n=2,115,881
Patients without HIV/AIDS, cancer,
ESRD, or transplantation
n=1,861,207
Patients without HIV/AIDS, cancer,
ESRD, or transplantation
n=35,150
Patients continuously enrolled for 12 months
prior to index hospitalization
n=866,821
Patients continuously enrolled for 12 months
prior to index hospitalization
n=25,141
Patients ≥18 years of age
n=792,908
Patients ≥18 years of age
n=24,955
Patients without negative/zero costs for the
first inpatient hospitalization
n=763,707
Patients without negative/zero costs for the
first inpatient hospitalization
n=24,686
Patients without unknown gender
n=763,605
Patients without unknown gender
n=24,684
Patients without other exclusionary
ICD-9-CM codes during index hospitalization
n=353,696
Patients continuously enrolled between the
discharge date for the first inpatient
hospitalization and end date
n=24,523
Patients continuously enrolled between the
discharge date for the first inpatient
hospitalization and end date
n=352,419
Stroke patients
n=11,883
No CVD hx
n=8415
Stroke hx
n=958
Patients matched 1:1
on age, gender, month
of index hospitalization,
length of follow-up,
CCI, and CVD history
Other CVD hx Stroke+other CVD hx
n=1398
n=1112
No CVD hx
n=8415
Control patients
n=11,883
Stroke hx
n=958
Other CVD hx Stroke+other CVD hx
n=1398
n=1112
Figure 1. Participant flow through the study cohort selection procedure with final study cohorts stratified by cardiovascular disease history. CCI indicates Charlson Comorbidity Index; ESRD, end-stage renal disease; hx, history.
matched control patients hospitalized for a noncardiovascular event.
Subjects and Methods
Data Source and Claims
This retrospective claims database analysis used anonymous eligibility, pharmacy claims, and medical claims data from a large US
managed-care health plan. This claims database is updated on a
regular basis and included ⱖ15 million enrollees insured through
their employers or as dependents of enrolled employees.
Medical claims are collected from all available sources (eg,
inpatient hospital, outpatient hospital, Emergency Department, physician’s office, and surgery center) for all types of provided services,
including specialty, preventive, and office-based treatments. Ninetyfive percent of medical claims data are captured within ⬇6 months
of payment of the underlying claim. Pharmacy claims are provided
by pharmacies and included drug name, dosage form, drug strength, fill
date, days of supply, and cost, allowing for longitudinal tracking of
medication refill patterns and changes in medications. Incorporation of
pharmacy claims data occurs within ⬇6 weeks of payment of the
underlying claim.
Study Cohorts
The study cohort selection procedure is shown in Figure 1. Patients
hospitalized for ischemic stroke between January 1, 2002 and
December 31, 2005 were identified from the claims database
according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) coding system currently
used to classify medical claims in the United States. Diagnosis codes
in the 433.xx series (where “x” indicates that any number was valid
as the fourth and fifth digit) were used for occlusion and stenosis of
precerebral arteries, and codes in the 434.xx series were used for
occlusion of cerebral arteries. Patients with hemorrhagic stroke were
excluded from the stroke cohort by not including diagnoses with
ICD-9-CM codes 430 to 432.9, which relate to intracranial hemorrhage. Patients with a stroke that had not been specified as ischemic
or hemorrhagic (ICD-9-CM: 436 [acute, but ill-defined, cerebrovascular disease]) were also excluded, as were those with a diagnosis of
transient ischemic attack (ICD-9-CM: 435.x). Patients with chronic
comorbidities that have a high mortality rate (ie, HIV/AIDS, cancer/
chemotherapy, end-stage renal disease, and transplantation) were
excluded from the final stroke cohort. A control cohort of patients
hospitalized during this period for an acute noncardiovascular event
was also identified among those who were not included in the stroke
cohort by: (1) extracting all facility claims with codes indicating
inpatient hospitalization; (2) excluding hospitalizations with diagnoses (primary or secondary position), procedures, and medications
for chronic disorders with a high mortality rate (ie, HIV/AIDS,
cancer/chemotherapy, end-stage renal disease, and transplantation);
(3) assessing the frequency of primary diagnosis and procedure codes on
the claims; (4) reviewing these diagnosis codes and excluding hospitalizations with diagnoses (primary position) associated with cardiovascular disease (CVD), routine or nonspecific visits (eg, pregnancy/childbirth, nausea/vomiting, and diarrhea), and mental disorders; and (5)
reviewing the length of hospital stay and total hospital costs. The final
comparison cohort consisted of those with an index hospitalization
without the codes and medications listed in supplemental Table I,
available online at http://stroke.ahajournals.org.
Downloaded from http://stroke.ahajournals.org/ by guest on July 4, 2015
Roberts et al
Table 1.
1427
Incremental Cardiovascular Costs After Stroke
Baseline Demographic and Clinical Characteristics of the Stroke and Control Cohorts by CVD History
Stroke Cohort
Control Cohort
Subgroups (Based on Prior Disease)
Parameter
All Patients
(n⫽11 883)
No CVD
(n⫽8415)
Stroke
(n⫽958)
Other CVD
(n⫽1398)
Subgroups (Based on Prior Disease)
Stroke⫹Other
CVD
(n⫽1112)
All Patients
(n⫽11 883)
No CVD
(n⫽8415)
Stroke
(n⫽958)
Other CVD
(n⫽1398)
Stroke⫹Other
CVD
(n⫽1112)
Age, mean (SD), y
57.8 (12.9)
55.5 (12.8)
60.9 (11.3)
63.4 (11.6)
65.7 (10.3)
57.7 (12.9)
55.3 (12.7)
60.9 (11.3)
63.3 (11.7)
65.7 (10.4)
Female, %
47.8
49.9
53.4
40.7
35.4
47.8
49.9
53.4
40.7
35.4
Follow-up, mean
(SD), d
550.6 (400.5)
524.1 (398.1)
625.1 (400.4)
602.5 (406.9)
622.1 (387.8)
550.9 (400.5)
524.4 (398.2)
624.8 (400.7)
602.6 (406.8)
622.2 (387.6)
CCI, mean (SD)
0.62 (0.92)
0.31 (0.62)
1.10 (0.76)
1.07 (1.03)
1.97 (1.12)
0.62 (0.92)
0.31 (0.62)
1.10 (0.76)
1.07 (1.03)
1.97 (1.12)
Hypertension
48.2
38.3
62.8
71.5
80.9
44.3
35.0
57.1
65.2
77.2
Lipid metabolism
disorders
37.6
28.1
48.2
60.7
71.1
39.3
31.2
49.9
59.5
66.5
Diseases of the
heart
36.1
19.7
41.0
88.1
90.3
37.2
21.1
45.4
86.7
90.0
24.6
15.7
33.0
43.9
60.7
25.3
17.3
33.5
41.3
58.8
6.0
3.4
6.2
12.7
17.5
6.1
4.0
7.7
10.7
15.0
ACE inhibitors
17.9
13.0
20.7
30.3
36.2
15.7
10.7
20.1
24.7
38.3
ARBs
10.5
8.6
12.5
15.0
17.2
10.2
7.9
14.5
14.1
19.2
CCBs
14.7
11.2
18.8
23.2
27.2
12.9
8.9
19.5
20.0
28.8
Diuretics
17.8
13.5
21.6
28.0
34.2
18.3
13.6
26.0
26.8
36.7
Other
(VDs/BBs)
1.4
1.0
2.4
2.3
2.6
1.3
0.9
2.3
1.9
2.8
11.3
9.7
11.0
15.6
18.1
10.4
7.1
14.2
16.6
24.6
5.9
5.0
4.7
9.3
9.4
5.4
3.5
8.1
8.5
13.7
Comorbidities, %
Medications, %
Antihyperlipidemics
Statins
Other (EZEs/
fibrates/BASs)
Antihypertensives
Antidiabetics
Oral
hypoglycemics
Insulin
ACE indicates angiotensin-converting enzyme; ARBs, angiotensin receptor blockers; BASs, bile acid sequestrants; BBs, -blockers; CCBs, calcium channel blockers;
CCI, Charlson Comorbidity Index; EZE, ezetimibe; VDs, vasodilators.
The first hospitalization during the identification period was
defined as the index hospitalization. A preindex baseline period was
defined as the 12 months preceding the index hospitalization
admission date, and the postindex follow-up period was defined as
the period between the index hospitalization discharge date and the
earliest of disenrollment, death, or June 30, 2006. Inclusion in the
final study sample was dependent on a patient being continuously
enrolled for ⱖ12 months before the index date through to the
discharge date for the index hospitalization, insured with drug and
medical benefits for the entire study, and ⱖ18 years of age in the
year of the index hospitalization.
Patients in the ischemic stroke cohort were paired with matched
controls on the basis of age (⫾1 year), sex, month of index
hospitalization, length of follow-up (⫾30 days), Charlson Comorbidity Index score (⫾1 point), and baseline CVD history. The stroke
and control cohorts were also stratified into subgroups according to
presence or absence of history of prior stroke or other CVD in the
preindex period. Evidence of stroke history was defined as any
medical claim having ICD-9-CM codes 433.xx to 436.xx, or a
pharmacy claim for anticoagulation or antiplatelet therapy. Evidence
of other CVD history was defined as any medical claim with a
diagnosis or procedure code indicating aortic and mitral valve
stenosis, MI, ischemic heart disease, angina pectoris, congestive
heart failure, congenital heart disease, coronary artery disease,
percutaneous transluminal coronary angioplasty, coronary artery
bypass graft, limb bypass surgery, asymmetrical septal hypertrophy,
malfunctioning prosthetic valve, constrictive pericarditis, heart transplant, subarachnoid hemorrhage, or a prescription claim for nitrates.
Cost and Resource Utilization Outcomes
The identification of stroke-related and non–stroke-related cardiovascular costs and resource use was based on the diagnosis and
procedure codes entered on medical claims (listed in supplemental
Table II). Cardiovascular pharmacy claims were identified for the
following drug classes: anticoagulants, antiplatelets, antihypertensives, statins, ezetimibe, bile acid sequestrants, fibrates, insulins, and
oral hypoglycemics. All-cause costs were calculated from all claims
regardless of diagnosis.
Cumulative costs (mean costs per patient within the specified time
window) were calculated for stroke-related, non–stroke-related cardiovascular, and all-cause medical services, as well as for cardiovascular pharmacy costs, for patients in each cohort who were
continuously enrolled for the entire period. All diagnosis and
procedure codes were used in the identification of related costs. Cost
calculations reflected the actual amount paid, including both the
patient liability (in the form of copayment and deductible) and the
health plan liability, to best reflect the true cost of care. Costs are
reported in US dollars and were adjusted for inflation to 2005
according to the medical component of the Consumer Price Index.
Cumulative risk of hospitalization (risk of an event within the
specified time window) was calculated for stroke-related and non–
stroke-related cardiovascular hospitalizations based on ICD-9-CM
Downloaded from http://stroke.ahajournals.org/ by guest on July 4, 2015
1428
Stroke
April 2009
Stroke-Related Costs at 6 Months
A
Stroke Cohort
Control Cohort
2000
Mean Cumulative Stroke-Related
Medical Costs Per Patient (US$)
P
Cardiovascular Costs and Hospitalizations in Managed-Care
Patients After Ischemic Stroke
Craig S. Roberts, PharmD, MPA; Philip B. Gorelick, MD, MPH; Xin Ye, PhD;
Carolyn Harley, PhD; George A. Goldberg, MD
Background and Purpose—Prior stroke confers an increased risk of future cardiovascular events. Because the incremental
economic impact of this added risk is unknown, we assessed the additional cardiovascular costs and hospitalizations
associated with ischemic stroke.
Methods—Patients hospitalized for ischemic stroke during 2002 to 2005 were identified from a large US managed-care plan and
matched to control patients hospitalized for a noncardiovascular acute event. Cumulative stroke-related and non–strokerelated cardiovascular medical costs were determined for each group. Stroke and nonstroke cardiovascular hospitalization
rates were calculated with the Kaplan–Meier method; risk of hospitalization was estimated with a Cox regression model.
Results—Stroke patients and matched controls (N⫽11 883) were identified (mean age ⬇58 years; 47.8% female).
Compared with controls, patients hospitalized for ischemic stroke had higher stroke and nonstroke cardiovascular
medical costs at 6 months (stroke: $1756 vs $50, P⬍0.01; nonstroke cardiovascular: $1437 vs $658, P⬍0.01) and 12
months (stroke: $2109 vs $68, P⬍0.01; nonstroke cardiovascular: $2203 vs $1167, P⬍0.01) of follow-up. Among
stroke patients, cumulative stroke and nonstroke cardiovascular hospitalization rates were 9.06% and 5.63% at 6 months,
respectively, and 21.09% and 22.05% at 36 months, respectively. Stroke patients were at significantly increased risk of
repeat stroke hospitalization (hazard ratio⫽12.55; 95% CI, 10.50 to 15.01) and nonstroke cardiovascular hospitalization
(hazard ratio⫽1.95; 95% CI, 1.77 to 2.14).
Conclusions—After ischemic stroke, patients have significantly greater stroke and nonstroke cardiovascular costs and
hospitalizations than do matched controls. Attention to total cardiovascular risk reduction in this population could
potentially reduce downstream costs. (Stroke. 2009;40:1425-1432.)
Key Words: stroke 䡲 health care costs 䡲 hospitalization 䡲 risk factors 䡲 managed care
S
troke represents a major public health problem in the
United States, where it is the third leading cause of
mortality, accounting for ⬎150 000 deaths annually, and is
one of the leading causes of long-term adult disability.1 There
are an estimated 5.8 million survivors of stroke in the United
States alone, and up to one third of stroke patients may be left
permanently disabled or require several months of institutional care after an attack.1
Patients with prior stroke are at increased risk of future
cerebrovascular events: of the ⬇780 000 strokes occurring in
the United States each year, ⬇180 000 are recurrent attacks.1
Ischemic strokes account for 87% of all strokes.1 Although a
repeat stroke is the most common secondary ischemic event
in the years after an ischemic stroke,2– 4 these patients are also
at increased risk of coronary events such as myocardial
infarction (MI) and cardiac death.5–7 The observation that
ischemic stroke may predict future cardiac events is indica-
tive of the shared risk factors and pathophysiologic mechanisms underlying these events and the systemic nature of
atherosclerotic vascular disease.
Owing to the high level of morbidity associated with
stroke, the economic burden of this disease is substantial. For
2008, it is estimated that stroke will cost the US economy
$65.5 billion in health care services, medications, and lost
productivity.1 Few studies have estimated the incremental
health care costs and resource utilization associated with
ischemic stroke, particularly those costs and hospitalizations
that arise from non–stroke-related cardiovascular events
(eg, MI, angina, revascularization, and heart failure) in the
poststroke follow-up period. Therefore, using claims data
from a large US managed-care health plan for 2002 to
2005, we assessed the long-term stroke-related and non–
stroke-related cardiovascular costs and hospitalization risk
in patients hospitalized for ischemic stroke compared with
Received August 12, 2008; accepted September 12, 2008.
From Pfizer Inc (C.S.R.), New York, NY; the University of Illinois at Chicago (P.B.G.); and i3 Innovus, Eden Prairie, Minn (X.Y., C.H.), and Santa
Monica, Calif (G.A.G.).
Correspondence to Craig S. Roberts, PharmD, MPA, Global Outcomes Research, Pfizer Inc, 235 East 42nd St, New York, NY 10017. E-mail
Craig.Roberts@pfizer.com
© 2009 American Heart Association, Inc.
Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.108.534354
1425
Downloaded from http://stroke.ahajournals.org/
by guest on July 4, 2015
1426
Stroke
April 2009
Stroke Cohort
Control Cohort
Patients hospitalized for ischemic stroke,
Jan 1, 2002–Dec 31, 2005
n=45,163
Patients hospitalized for a non-stroke event,
Jan 1, 2002–Dec 31, 2005
n=2,115,881
Patients without HIV/AIDS, cancer,
ESRD, or transplantation
n=1,861,207
Patients without HIV/AIDS, cancer,
ESRD, or transplantation
n=35,150
Patients continuously enrolled for 12 months
prior to index hospitalization
n=866,821
Patients continuously enrolled for 12 months
prior to index hospitalization
n=25,141
Patients ≥18 years of age
n=792,908
Patients ≥18 years of age
n=24,955
Patients without negative/zero costs for the
first inpatient hospitalization
n=763,707
Patients without negative/zero costs for the
first inpatient hospitalization
n=24,686
Patients without unknown gender
n=763,605
Patients without unknown gender
n=24,684
Patients without other exclusionary
ICD-9-CM codes during index hospitalization
n=353,696
Patients continuously enrolled between the
discharge date for the first inpatient
hospitalization and end date
n=24,523
Patients continuously enrolled between the
discharge date for the first inpatient
hospitalization and end date
n=352,419
Stroke patients
n=11,883
No CVD hx
n=8415
Stroke hx
n=958
Patients matched 1:1
on age, gender, month
of index hospitalization,
length of follow-up,
CCI, and CVD history
Other CVD hx Stroke+other CVD hx
n=1398
n=1112
No CVD hx
n=8415
Control patients
n=11,883
Stroke hx
n=958
Other CVD hx Stroke+other CVD hx
n=1398
n=1112
Figure 1. Participant flow through the study cohort selection procedure with final study cohorts stratified by cardiovascular disease history. CCI indicates Charlson Comorbidity Index; ESRD, end-stage renal disease; hx, history.
matched control patients hospitalized for a noncardiovascular event.
Subjects and Methods
Data Source and Claims
This retrospective claims database analysis used anonymous eligibility, pharmacy claims, and medical claims data from a large US
managed-care health plan. This claims database is updated on a
regular basis and included ⱖ15 million enrollees insured through
their employers or as dependents of enrolled employees.
Medical claims are collected from all available sources (eg,
inpatient hospital, outpatient hospital, Emergency Department, physician’s office, and surgery center) for all types of provided services,
including specialty, preventive, and office-based treatments. Ninetyfive percent of medical claims data are captured within ⬇6 months
of payment of the underlying claim. Pharmacy claims are provided
by pharmacies and included drug name, dosage form, drug strength, fill
date, days of supply, and cost, allowing for longitudinal tracking of
medication refill patterns and changes in medications. Incorporation of
pharmacy claims data occurs within ⬇6 weeks of payment of the
underlying claim.
Study Cohorts
The study cohort selection procedure is shown in Figure 1. Patients
hospitalized for ischemic stroke between January 1, 2002 and
December 31, 2005 were identified from the claims database
according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) coding system currently
used to classify medical claims in the United States. Diagnosis codes
in the 433.xx series (where “x” indicates that any number was valid
as the fourth and fifth digit) were used for occlusion and stenosis of
precerebral arteries, and codes in the 434.xx series were used for
occlusion of cerebral arteries. Patients with hemorrhagic stroke were
excluded from the stroke cohort by not including diagnoses with
ICD-9-CM codes 430 to 432.9, which relate to intracranial hemorrhage. Patients with a stroke that had not been specified as ischemic
or hemorrhagic (ICD-9-CM: 436 [acute, but ill-defined, cerebrovascular disease]) were also excluded, as were those with a diagnosis of
transient ischemic attack (ICD-9-CM: 435.x). Patients with chronic
comorbidities that have a high mortality rate (ie, HIV/AIDS, cancer/
chemotherapy, end-stage renal disease, and transplantation) were
excluded from the final stroke cohort. A control cohort of patients
hospitalized during this period for an acute noncardiovascular event
was also identified among those who were not included in the stroke
cohort by: (1) extracting all facility claims with codes indicating
inpatient hospitalization; (2) excluding hospitalizations with diagnoses (primary or secondary position), procedures, and medications
for chronic disorders with a high mortality rate (ie, HIV/AIDS,
cancer/chemotherapy, end-stage renal disease, and transplantation);
(3) assessing the frequency of primary diagnosis and procedure codes on
the claims; (4) reviewing these diagnosis codes and excluding hospitalizations with diagnoses (primary position) associated with cardiovascular disease (CVD), routine or nonspecific visits (eg, pregnancy/childbirth, nausea/vomiting, and diarrhea), and mental disorders; and (5)
reviewing the length of hospital stay and total hospital costs. The final
comparison cohort consisted of those with an index hospitalization
without the codes and medications listed in supplemental Table I,
available online at http://stroke.ahajournals.org.
Downloaded from http://stroke.ahajournals.org/ by guest on July 4, 2015
Roberts et al
Table 1.
1427
Incremental Cardiovascular Costs After Stroke
Baseline Demographic and Clinical Characteristics of the Stroke and Control Cohorts by CVD History
Stroke Cohort
Control Cohort
Subgroups (Based on Prior Disease)
Parameter
All Patients
(n⫽11 883)
No CVD
(n⫽8415)
Stroke
(n⫽958)
Other CVD
(n⫽1398)
Subgroups (Based on Prior Disease)
Stroke⫹Other
CVD
(n⫽1112)
All Patients
(n⫽11 883)
No CVD
(n⫽8415)
Stroke
(n⫽958)
Other CVD
(n⫽1398)
Stroke⫹Other
CVD
(n⫽1112)
Age, mean (SD), y
57.8 (12.9)
55.5 (12.8)
60.9 (11.3)
63.4 (11.6)
65.7 (10.3)
57.7 (12.9)
55.3 (12.7)
60.9 (11.3)
63.3 (11.7)
65.7 (10.4)
Female, %
47.8
49.9
53.4
40.7
35.4
47.8
49.9
53.4
40.7
35.4
Follow-up, mean
(SD), d
550.6 (400.5)
524.1 (398.1)
625.1 (400.4)
602.5 (406.9)
622.1 (387.8)
550.9 (400.5)
524.4 (398.2)
624.8 (400.7)
602.6 (406.8)
622.2 (387.6)
CCI, mean (SD)
0.62 (0.92)
0.31 (0.62)
1.10 (0.76)
1.07 (1.03)
1.97 (1.12)
0.62 (0.92)
0.31 (0.62)
1.10 (0.76)
1.07 (1.03)
1.97 (1.12)
Hypertension
48.2
38.3
62.8
71.5
80.9
44.3
35.0
57.1
65.2
77.2
Lipid metabolism
disorders
37.6
28.1
48.2
60.7
71.1
39.3
31.2
49.9
59.5
66.5
Diseases of the
heart
36.1
19.7
41.0
88.1
90.3
37.2
21.1
45.4
86.7
90.0
24.6
15.7
33.0
43.9
60.7
25.3
17.3
33.5
41.3
58.8
6.0
3.4
6.2
12.7
17.5
6.1
4.0
7.7
10.7
15.0
ACE inhibitors
17.9
13.0
20.7
30.3
36.2
15.7
10.7
20.1
24.7
38.3
ARBs
10.5
8.6
12.5
15.0
17.2
10.2
7.9
14.5
14.1
19.2
CCBs
14.7
11.2
18.8
23.2
27.2
12.9
8.9
19.5
20.0
28.8
Diuretics
17.8
13.5
21.6
28.0
34.2
18.3
13.6
26.0
26.8
36.7
Other
(VDs/BBs)
1.4
1.0
2.4
2.3
2.6
1.3
0.9
2.3
1.9
2.8
11.3
9.7
11.0
15.6
18.1
10.4
7.1
14.2
16.6
24.6
5.9
5.0
4.7
9.3
9.4
5.4
3.5
8.1
8.5
13.7
Comorbidities, %
Medications, %
Antihyperlipidemics
Statins
Other (EZEs/
fibrates/BASs)
Antihypertensives
Antidiabetics
Oral
hypoglycemics
Insulin
ACE indicates angiotensin-converting enzyme; ARBs, angiotensin receptor blockers; BASs, bile acid sequestrants; BBs, -blockers; CCBs, calcium channel blockers;
CCI, Charlson Comorbidity Index; EZE, ezetimibe; VDs, vasodilators.
The first hospitalization during the identification period was
defined as the index hospitalization. A preindex baseline period was
defined as the 12 months preceding the index hospitalization
admission date, and the postindex follow-up period was defined as
the period between the index hospitalization discharge date and the
earliest of disenrollment, death, or June 30, 2006. Inclusion in the
final study sample was dependent on a patient being continuously
enrolled for ⱖ12 months before the index date through to the
discharge date for the index hospitalization, insured with drug and
medical benefits for the entire study, and ⱖ18 years of age in the
year of the index hospitalization.
Patients in the ischemic stroke cohort were paired with matched
controls on the basis of age (⫾1 year), sex, month of index
hospitalization, length of follow-up (⫾30 days), Charlson Comorbidity Index score (⫾1 point), and baseline CVD history. The stroke
and control cohorts were also stratified into subgroups according to
presence or absence of history of prior stroke or other CVD in the
preindex period. Evidence of stroke history was defined as any
medical claim having ICD-9-CM codes 433.xx to 436.xx, or a
pharmacy claim for anticoagulation or antiplatelet therapy. Evidence
of other CVD history was defined as any medical claim with a
diagnosis or procedure code indicating aortic and mitral valve
stenosis, MI, ischemic heart disease, angina pectoris, congestive
heart failure, congenital heart disease, coronary artery disease,
percutaneous transluminal coronary angioplasty, coronary artery
bypass graft, limb bypass surgery, asymmetrical septal hypertrophy,
malfunctioning prosthetic valve, constrictive pericarditis, heart transplant, subarachnoid hemorrhage, or a prescription claim for nitrates.
Cost and Resource Utilization Outcomes
The identification of stroke-related and non–stroke-related cardiovascular costs and resource use was based on the diagnosis and
procedure codes entered on medical claims (listed in supplemental
Table II). Cardiovascular pharmacy claims were identified for the
following drug classes: anticoagulants, antiplatelets, antihypertensives, statins, ezetimibe, bile acid sequestrants, fibrates, insulins, and
oral hypoglycemics. All-cause costs were calculated from all claims
regardless of diagnosis.
Cumulative costs (mean costs per patient within the specified time
window) were calculated for stroke-related, non–stroke-related cardiovascular, and all-cause medical services, as well as for cardiovascular pharmacy costs, for patients in each cohort who were
continuously enrolled for the entire period. All diagnosis and
procedure codes were used in the identification of related costs. Cost
calculations reflected the actual amount paid, including both the
patient liability (in the form of copayment and deductible) and the
health plan liability, to best reflect the true cost of care. Costs are
reported in US dollars and were adjusted for inflation to 2005
according to the medical component of the Consumer Price Index.
Cumulative risk of hospitalization (risk of an event within the
specified time window) was calculated for stroke-related and non–
stroke-related cardiovascular hospitalizations based on ICD-9-CM
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1428
Stroke
April 2009
Stroke-Related Costs at 6 Months
A
Stroke Cohort
Control Cohort
2000
Mean Cumulative Stroke-Related
Medical Costs Per Patient (US$)
P