(Circulation. 1999;99:370-376.)
© 1999 American Heart Association, Inc.
Clinical Investigation and Reports |
From the Duke Clinical Research Institute, Durham, NC (C.Y.T., C.B.G., J.D.K., K.W.M., N.C.-C., R.M.C., D.B.M.); Harbin Clinic, Rome, Ga (M.A.S.); the Cleveland Clinic Foundation, Cleveland, Ohio (E.J.T.); Henry Ford Hospital, Detroit, Mich (W.D.W.); Erasmus University, Rotterdam, Netherlands (M.L.S.); University of Massachusetts Medical Center, Worcester (J.M.G.); and Green Lane Hospital, Auckland, New Zealand (H.W.).
Correspondence to Chen Y. Tung, MD, Box 2966, Duke University Medical Center, Durham, NC 27710. E-mail tung0001{at}mc.duke.edu
| Abstract |
|---|
|
|
|---|
30 000 US patients
each year. This number is expected to rise with the increasing use of
thrombolytic therapy for MI. However, no data exist for
the economic effect of stroke in the setting of acute MI (AMI). The
purpose of this prospective study was to assess the effect of stroke on
medical resource use and costs in AMI patients in the United
States.
Methods and ResultsMedical resource use and cost data were
prospectively collected for 2566 randomly selected US GUSTO I patients
(from 23 105 patients) and for the 321 US GUSTO I patients who
developed nonbypass surgeryrelated stroke during the baseline
hospitalization. Follow-up was for 1 year. All costs are expressed in
1993 US dollars. During the baseline hospitalization, stroke was
associated with a reduction in cardiac procedure rates and an increase
in length of stay, despite a hospital mortality rate of 37%. Together
with stroke-related procedural costs of $2220 per patient, the baseline
medical costs increased by 44% ($29 242 versus $20 301,
P<0.0001). Follow-up medical costs were substantially
higher for stroke survivors ($22 400 versus $5282,
P<0.0001), dominated by the cost of institutional care.
The main determinant for institutional care was discharge disability
status. The cumulative 1-year medical costs for stroke patients were
$15 092 higher than for no-stroke patients. Hemorrhagic stroke
patients had a much higher hospital mortality rate than
nonhemorrhagic stroke patients (53% versus 15%,
P<0.001), which was associated with
$7200 lower mean
baseline hospitalization cost. At discharge, hemorrhagic stroke
patients were more likely to be disabled (68% versus 46%,
P=0.002).
ConclusionsIn this first large prospective economic study of stroke in AMI patients, we found that strokes were associated with a 60% ($15 092) increase in cumulative 1-year medical costs. Baseline hospitalization costs were 44% higher because of longer mean lengths of stay. Stroke type was a key determinant of baseline cost. Follow-up costs were more than quadrupled for stroke survivors because of the need for institutional care. Disability level was the main determinant of institutional care and thus of follow-up costs.
Key Words: stroke myocardial infarction cost-benefit analysis
| Introduction |
|---|
|
|
|---|
As part of the Economics and Quality of Life (EQOL) substudy for the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries Study (GUSTO I), we prospectively collected, by structured interview, detailed resource use information on North American AMI patients who developed a stroke during their baseline hospitalization. Only US patients were included in this economic analysis. To evaluate the effect of stroke on resource use and costs, strokes due to bypass surgery were excluded. The purpose of this study is to describe the effects of stroke on medical resource use and costs for AMI patients in the United States.
| Methods |
|---|
|
|
|---|
|
Demographic/Clinical Data
Baseline clinical and demographic variables collected on the
GUSTO clinical case report form included age, sex,
cardiovascular risk factors, prior MI, prior angina,
prior revascularization, cerebrovascular disease,
myocardial infarct location, and Killip class.6
At hospital discharge, patients were prospectively classified by the site investigator as "disabled" if they had a moderate (substantial limitation of activity and capability) or severe (inability to live independently or work) deficit from their stroke.3
Reporting and Classification of Strokes
As previously described, suspected strokes were reported by
investigators to Duke Coordinating Center, and selected stroke-related
data were collected on an ancillary case report form.3
Stroke was defined as an "acute new neurological deficit resulting in
death or lasting for more than 24 hours, as classified by a physician,
with supporting information including brain images and
neurological/neurosurgical evaluation."3 All suspected
stroke patients were advised to have either CT or MRI. Among the stroke
cohort, 97% had at least 1 neuroimaging study. A stroke review
committee reviewed all adverse neurological events. Details regarding
the adjudication process have been reported
previously.3
Strokes were divided into 4 main categories: primary intracranial hemorrhage, nonhemorrhagic infarct, hemorrhagic conversion of infarct, and unknown. The specific criteria used to make these distinctions have been published.3 For the present study, primary intracranial hemorrhage and hemorrhagic conversion are considered "hemorrhagic strokes."
Stroke Data Collected
For the present analysis, we extracted
stroke-related resource utilization from the stroke ancillary form.
Stroke specific resource use included neurology and/or neurosurgery
consultations, head CTs/MRIs, echocardiograms, electroencephalograms,
carotid duplex studies, carotid arteriograms, and neurosurgical
procedures.
Medical Resource and Cost Data
Data on medical resource consumption during the baseline
hospitalization were collected on the case report form. To collect
follow-up resource consumption data, we conducted telephone interviews
at 30 days, 6 months, and 1 year with stroke survivors.4
If the patient was unable to participate, brief proxy interviews were
conducted with a family or household member (36% of 30-day interviews
and 32% of 1-year interviews). In each interview, patients were asked
about medical care between interviews, including rehospitalization,
cardiac catheterization, PTCA, CABG, AMI, institutional
care, and 11 types of outpatient visits. All patient-reported cardiac
procedures were verified with the facility that provided medical care.
For those patients without baseline stroke-related procedural cost
data, cost was computed on the basis of existing patient data
stratified by stroke type (hemorrhagic or nonhemorrhagic). For this
study cohort, resource units were converted to medical costs (1993 US
dollars) by use of the methodology of the GUSTO I cost-effectiveness
analysis.5 For the baseline hospitalization, cost
weights for each major resource consumed were developed from the Duke
Transition System I cost accounting system. For each follow-up
admission, costs were based on Medicare Diagnostic Related
Group reimbursement rates. Physician fees and outpatient visits were
assigned costs according to the Medicare Fee Schedule. Nursing home
costs and rehabilitation hospital costs were assigned by use of per
diems obtained from institutions that provided care for GUSTO I
patients.
Data Analysis
In this study, all 4 thrombolytic treatment
groups in GUSTO were combined. To describe the characteristics of the
study population, we used means and SDs for continuous variables,
and medians, percentages, and interquartile ranges (25th to 75th
percentiles) for discrete variables. Univariate tests
were performed with standard contingency table
2 tests for categorical variables and the
Wilcoxon rank-sum test or nonparametric ANOVA for
continuous variables. To examine the predictors and correlates of
medical cost, we used multivariable linear regression
analyses with logarithmic transformation of the baseline
hospitalization, follow-up, and cumulative 1-year costs.
| Results |
|---|
|
|
|---|
|
Of the 321 strokes, 172 (53%) were hemorrhagic, 141 (44%) were nonhemorrhagic, and 8 (2%) were unclassified. Of the 172 hemorrhagic strokes, 152 were primary intracranial hemorrhages. The hospital mortality rates were 53% for hemorrhagic stroke and 15% for nonhemorrhagic stroke. Among the stroke survivors, hemorrhagic and nonhemorrhagic stroke patients had similar 1-year survival rates (79% versus 83%, P=NS), although hemorrhagic stroke patients were more likely to be disabled than nonhemorrhagic patients at discharge (68% versus 46%, P=0.002).
Effects of Stroke on Medical Resource Consumption and
Costs
During the baseline hospitalization, the stroke cohort had a much
lower rate of cardiac catheterization (40% versus
72%, P<0.001), PTCA (16% versus 30%,
P<0.001), and CABG (5% versus 13%, P<0.001)
than the no-stroke cohort (Table 2
).
Conversely, stroke increased the length of stay, by 1.6 days in the
intensive care unit (ICU) (P<0.0001) and 2.6 days on the
non-ICU (P<0.0001) wards. Stroke-related procedures added
an average of $2220 to the baseline hospitalization cost. These shifts
in medical resource use resulted in a 44% increase ($29 242 versus
$20 301, P<0.0001) in the average cost of the baseline
hospitalization for the stroke versus the no-stroke cohort (Table 2
).
|
During follow-up, the medical costs of the stroke survivors were more
than quadruple those of the no-stroke cohort ($22 400 versus $5282,
P<0.0001). The total numbers of hospitalizations and total
incremental costs for hospital care were approximately equal (Table 3
). There were no differences in
outpatient costs. Stroke patients continued to have lower rates of
cardiac catheterization (13% versus 20%,
P=0.02) and PTCA (5% versus 12%, P=0.001) than
the no-stroke cohort. The higher follow-up costs were entirely a result
of the greater need for institutional care among the stroke survivors
(37% versus 2%, P<0.0001).
|
Cumulative 1-year costs were 60% higher for stroke patients ($40 192 versus $25 098, P<0.0001). Overall, the 321 patients in the stroke cohort increased the cumulative 1-year medical costs of the 23 105 US GUSTO I patients by $4.85 million, representing an average increase in direct costs of $210 per AMI patient. The greater cost occurred despite a much higher 1-year mortality rate (49% versus 9.8%) and lower rates of all cardiac procedures: cardiac catheterization (44% versus 79%, P<0.001), PTCA (19% versus 37%, P<0.001), and CABG (9% versus 19%, P<0.001).
Linear multivariable regression cost models were constructed to
identify the major predictors of the baseline hospitalization,
follow-up, and cumulative 1-year costs. Demographics, cardiac risk
factors, baseline medical characteristics, and stroke-specific
variables (stroke occurrence, stroke type, and discharge disability
level) were analyzed. For baseline costs, stroke occurrence and
stroke type were the main predictors of baseline hospitalization cost.
The main predictor of follow-up costs was discharge disability level.
As for cumulative 1-year costs, the main determinants were stroke
occurrence, stroke type, prior angina, and diabetes (Table 4
).
|
Effects of Stroke Type on Medical Resource Consumption and
Costs
Hemorrhagic strokes were associated with a much higher (53%
versus 15%, P<0.001) and earlier (50% by day 3) hospital
mortality rate than nonhemorrhagic strokes. As a result, the average
length of stay for hemorrhagic stroke patients was 5 days shorter
(P<0.01). Hemorrhagic stroke patients also had sharply
lower rates of invasive cardiac procedures than nonhemorrhagic stroke
patients, who had rates of invasive cardiac procedures similar to those
of the no-stroke cohort (Table 5
).
Compared with no-stroke patients, baseline medical costs for
nonhemorrhagic stroke patients were $13 498 higher and costs for
hemorrhagic stroke patients were $6318 higher (Table 5
). For
stroke patients who survived to discharge, there were no significant
differences between hemorrhagic stroke and nonhemorrhagic stroke
survivors in mean length of stay or cost.
|
Effects of Disability Level on Medical Resource Use and Costs in
Stroke Survivors
Of the stroke survivors, 55% were disabled at discharge. During
follow-up, institutional care was necessary for 64% of the disabled
patients versus 7% of the nondisabled patients. No significant
differences in the rate of cardiac procedures or hospitalizations
between the 2 groups were observed. The higher follow-up costs of the
disabled patients ($37 190 versus $6640, P<0.0001) were
accounted for by their greater need for institutional care (Table 6
).
|
| Discussion |
|---|
|
|
|---|
Major Findings
Strokes increased the average 1-year medical costs of AMI by 60%
($40 192 versus $25 098), despite a high early mortality rate and
much lower rates of cardiac procedures in the stroke cohort. The
drivers of the cost increase were longer lengths of stay in stroke
survivors, stroke-related procedural costs at baseline, and greater
need for institutional care for stroke survivors during follow-up.
Among the stroke cohort, the main determinant of baseline hospitalization cost was the stroke type, with the hemorrhagic strokes averaging $26 619 and nonhemorrhagic strokes averaging $33 799. The lower costs associated with hemorrhagic strokes were due to the high hospital mortality rate (53%), which led to shorter lengths of stay and fewer invasive cardiac procedures. For hemorrhagic stroke survivors, the length of stay and baseline hospitalization costs were similar to those of nonhemorrhagic stroke patients. The only previous literature on stroke costs discusses patients with isolated strokes, in whom the stroke type (subarachnoid hemorrhage, intracerebral hemorrhage, and ischemic stroke) was the major determinant of cost.7 8 Holloway and colleagues compared the baseline hospital costs for all stroke patients seen during 1992 at 5 academic medical centers.8 Using ICD-9 cerebrovascular subgroups, they found the mean hospital costs were $21 535 for intracerebral hemorrhage and $9882 for ischemic stroke. Demographic factors, such as age, were not significant determinants of baseline hospitalization cost. Postdischarge costs were not examined. Thus, in contrast to our results, these studies found that hemorrhagic strokes were associated with higher costs than nonhemorrhagic (ischemic) strokes. The explanation for the divergent results resides in the higher and earlier mortality rate of AMI patients treated with thrombolytics who develop hemorrhagic strokes compared with isolated hemorrhagic strokes (53% versus 21%).8 Consequently, AMI patients with strokes had shorter lengths of stay and consumed fewer resources.
During follow-up, the main predictor of cost was not stroke type. The higher cost for stroke survivors was driven by the cost of institutional care, the need for which was determined largely by the discharge disability level. Stroke patients who were disabled at discharge had $37 190 in subsequent costs out to 12 months, compared with $6640 for nondisabled stroke patients. Taylor and coworkers7 used Medicare claims and other national data sources to construct an epidemiological model of the lifetime costs of incident strokes occurring in 1990. In their study, stroke type and age were the main drivers of follow-up cost. However, like other cost studies of patients with isolated stroke, they did not evaluate global disability level as a determinant of cost.
Given the differences in demographics and cardiac risk factors between the stroke and no-stroke groups, one hypothesis for the higher medical costs of stroke patients was that they were older, "sicker" patients. However, multivariable regression models of cost revealed that demographic factors such as age were not significant cost predictors. The strongest predictors of cumulative 1-year costs were stroke occurrence and stroke type, and only prior angina and diabetes were independent clinical predictors of 1-year costs.
Implications of Findings
Extrapolation of our results to the estimated 30 000 Americans
who develop strokes while hospitalized for an AMI1 shows
that such strokes increase the annual national costs for AMI care by
$458 million during the year after stroke. Consequently, new
therapeutic strategies that significantly alter the stroke rate may
have important economic consequences at a national or health care
systemwide level that are independent of their effects on other
outcomes. Hillegass and colleagues9 previously showed that
a more effective reperfusion strategy that also increased the stroke
rate over current thrombolytic therapy rates can still
yield an acceptable risk-to-benefit ratio. However, several recent
clinical trials have been stopped because of increased hemorrhagic
stroke rates,10 11 and it seems quite unlikely that
clinicians will accept a more effective thrombolytic
regimen in exchange for an increased stroke rate. Current AMI clinical
trials are evaluating combination fibrinolytic, antiplatelet, and
antithrombin regimens at reduced doses, which may improve
coronary reperfusion at a lower stroke risk. Our data suggest
that these regimens have the potential to produce important cost
savings in AMI care.
Strokes were associated with significant shifts in medical resource use, particularly cardiac resource use. The rates of invasive cardiac procedures for the stroke cohort were nearly half those of the no-stroke cohort. Most of the reduction in cardiac procedures occurred at the baseline hospitalization. However, this effect extended into follow-up, with both disabled and nondisabled stroke patients having lower rates of cardiac catheterization and PTCA than the no-stroke cohort. Given the low rates of cardiac procedures at baseline hospitalization, one would expect a "catch-up" phenomenon during follow-up, which was absent even among the nondisabled stroke patients. This effect of stroke in the management of coronary disease is likely to alter the long-term prognosis of these coronary disease patients.
Contrary to prior studies, age was not a significant predictor of cost in stroke patients. However, because the effect of stroke on AMI costs is directly related to the incidence of stroke, any factor that substantially increases the stroke rate has significant cost consequences. AMI studies on thrombolytics have demonstrated that with increasing age, there is greater stroke risk and less survival benefit.3 12 The meta-analysis by the Fibrinolytic Therapy Trialists' Collaboration Group indicated that the use of thrombolytics in AMI patients >75 years old results in 10 lives saved per 1000 patients, compared with 27 lives saved per 1000 patients 65 to 74 years old.13 The combination of lower efficacy and the higher stroke rate in patients >75 years old calls into question whether alternative reperfusion strategies that have lower stroke rates (such as primary angioplasty) would be preferred in the elderly.
Limitations
Several caveats should be considered with regard to our study.
First, costs for the baseline hospitalization were estimated from the
Duke cost accounting system,5 not directly at each
participating institution. Thus, the absolute magnitude of baseline
cost differences observed in this study may not represent costs
at other medical centers. Second, the available follow-up in GUSTO I
extends only to 1 year. Therefore, our study provides an incomplete
picture of the lifetime economic consequences of strokes in AMI
patients. Finally, neuroimaging studies were performed in a number of
AMI patients without stroke to "rule out" a stroke. Data on these
resources were not collected and are not accounted for in the
analysis.
Conclusions
This prospective study measured the effect of stroke on cost and
medical resource use in AMI and examined the main determinants of cost.
Overall, compared with the no-stroke cohort, stroke increased the
average 1-year medical costs by 60% ($15 094). The early economic
effects were due to a high early mortality rate, which decreased
invasive cardiac procedure use after stroke (more pronounced in
patients with hemorrhagic strokes, who had the highest mortality rate)
and longer length of stay among the stroke survivors. After discharge,
disability level was the principal determinant of cost, with highest
institutional care need and lowest cardiac procedure rates in patients
with major disability.
| Acknowledgments |
|---|
Received April 9, 1998; revision received September 30, 1998; accepted October 9, 1998.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
M. D. Schleinitz and P. A. Heidenreich A Cost-Effectiveness Analysis of Combination Antiplatelet Therapy for High-Risk Acute Coronary Syndromes: Clopidogrel plus Aspirin versus Aspirin Alone Ann Intern Med, February 15, 2005; 142(4): 251 - 259. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Rundek, K. Nielsen, S. Phillips, K. C. Johnston, M. Hux, D. Watson, and for the GAIN Americas Investigators Health Care Resource Use After Acute Stroke in the Glycine Antagonist in Neuroprotection (GAIN) Americas Trial Stroke, June 1, 2004; 35(6): 1368 - 1374. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. M. Akkerhuis, J. W. Deckers, A. M. Lincoff, J. E. Tcheng, E. Boersma, K. Anderson, C. Balog, R. M. Califf, E. J. Topol, and M. L. Simoons Risk of Stroke Associated With Abciximab Among Patients Undergoing Percutaneous Coronary Intervention JAMA, July 4, 2001; 286(1): 78 - 82. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. A. Ganz, K. M. Kuntz, G. A. Jacobson, and J. Avorn Cost-Effectiveness of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitor Therapy in Older Patients with Myocardial Infarction Ann Intern Med, May 16, 2000; 132(10): 780 - 787. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. H. Lichtman, H. M. Krumholz, Y. Wang, M. J. Radford, and L. M. Brass Risk and Predictors of Stroke After Myocardial Infarction Among the Elderly: Results From the Cooperative Cardiovascular Project Circulation, March 5, 2002; 105(9): 1082 - 1087. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Circulation Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 1999 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |