(Stroke. 1999;30:1326-1332.)
© 1999 American Heart Association, Inc.
Original Contributions |
From the Department of Clinical and Biological Neurosciences, Stroke Unit, INSERM U 438, University Hospital, Grenoble, France (A.J., M.H.); Service de Pharmacologie, Clinique EA 643, Claude Bernard University, Lyon, France (C.C., F.B.); Service de Neurologie, University Hospital, Clermont-Ferrand, France (A.D.); Service de Neurologie, University Hospital, Besançon, France (T.M.); and the Acute Stroke Unit, University Department of Medicine and Therapeutics, Western Infirmary, Glasgow, UK (K.R.L.).
Correspondence to Assia Jaillard, Service de NeurologieUnité d'Urgences Cérébrovasculaires, Centre Hospitalier Universitaire de Grenoble, BP 217-38043 Grenoble Cedex, France. E-mail Assia.Jaillard{at}ujf-grenoble.fr
| Abstract |
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MethodsWe performed a post hoc analysis of MAST-E data designed to assess the safety and efficacy of streptokinase administered intravenously within 6 hours of stroke onset. HT included all intracerebral hemorrhages and symptomatic hemorrhages (SHT) associated with clinical worsening. The predictors of HT and SHT were determined using multivariate modeling.
ResultsAmong the 310 patients included, 159 patients had HT and 37 SHT (97 and 33 in the streptokinase group and 62 and 4 in the placebo group, respectively). Patients with SHT had significantly more atrial fibrillation, diabetes mellitus, no heparin use, streptokinase treatment, and early CT signs. In the multivariate analysis, HT was predicted by early CT signs and streptokinase treatment. SHT was predicted by diabetes mellitus, early CT signs, streptokinase treatment, and the interaction between streptokinase treatment and decreased level of consciousness. Among the streptokinase-treated patients, the same predictors remained.
ConclusionsThe relative risks of HT after streptokinase were in the same range in MAST-E as in other streptokinase and tPA trials. Early CT signs were strong predictors of both HT and SHT, stressing that these patients are at high risk of bleeding. In our study, the predictors of HT and SHT were similar to those of tPA trials in acute stroke.
Key Words: cerebral hemorrhage clinical trials streptokinase stroke, acute
| Introduction |
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| Subjects and Methods |
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Cerebral HT, assessed either on CT scans by the Neuroradiologic Reviewing Committee or by autopsy, was considered to be both the symptomatic and asymptomatic cerebral HT. SHT were defined as clinical deterioration temporally related to HT documented by CT scan or autopsy, as adjudicated independently by the Critical Events Reviewing Committee.
Demographic characteristics, medical history, vascular risk factors, baseline clinical characteristics and neurological state (MAST-E score, the items and the sum) were collected. Administration of anticoagulants or antiplatelets agents during hospitalization was allowed to give the placebo group patients access to the best treatment available in the investigators' opinion. Use of heparin or antiplatelets agents during hospitalization was recorded.
Statistical Analysis
We analyzed HT and SHT using the
2 test, Student t test, or
the Fisher's exact test, as appropriate. Subgroup analyses
were performed according to the following variables: age; sex; body
weight; atrial fibrillation; history of hypertension, diabetes
mellitus, previous stroke, or transient ischemic attack of the
brain; systolic blood pressure and diastolic blood
pressure; MAST-E score18 ; hand, arm, and leg
paresias; level of consciousness at admission; side of the
ischemia; cerebral atrophy; early CT signs of lentiform nucleus
attenuation, insular ribbon contrast attenuation, hemispheric sulcus
effacement, and hyperdense MCA; streptokinase treatment allocation;
antithrombotic-associated treatment (heparin, antiplatelet agents);
and delay from stroke onset to treatment.
A logistic forward stepwise regression model was used to define predictors of HT after adjustment for the effect of confounding variables.19 We chose to include in the initial model all variables associated with hemorrhage in univariate analysis with a value of P<0.2. We also included all variables reported to be related to cerebral hemorrhages in other studies: age, sex, weight, hypertension, previous stroke or transient ischemic attack, atrial fibrillation, systolic and diastolic blood pressures, and severity at admission.12 20 21 Because of the small number of patients, logistic regression was performed on symptomatic cerebral hemorrhages both in the total population and in the streptokinase group, which included most SHT. We tested the interactions among the selected variables and refit the model. We chose a value of P=0.05 as a level of statistical significance and did not correct for multiple comparisons. We assessed the sensivity, specificity, positive and negative predictive values, and efficiency of each mutivariate model for HT and SHT.
| Results |
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Hemorrhagic Transformation
Comparisons of baseline characteristics, treatments received, and
CT scan signs between patients with and without HT are reported in
Tables 1
and 2
. Streptokinase treatment and
early CT scan signs (Figure 1
) differed significantly between
the 2 groups and remained significantly linked with HT in the
multivariate stepwise logistic regression (Table 3
). Age, body weight, atrial
fibrillation, systolic and diastolic blood
pressures, the delay from stroke onset to treatment, and heparin and
antiplatelet agent use were not kept in the
multivariate model. The specificity of the model was
44.9% (95% CI, 39% to 51%), the sensitivity 80% (95% CI, 75% to
85%), the positive predictive value 66% (95% CI, 60% to 72%), the
negative predictive value 63% (95% CI, 57% to 69%), and the global
efficiency 65% (95% CI, 59% to 71%). When we selected the
streptokinase group, early CT signs remained the sole predictors of HT
(Table 3
).
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Symptomatic Hemorrhages
Among the 157 patients with HT, 37 had SHT (33 in the
streptokinase group and 4 in the placebo group). Comparisons of the
baseline characteristics, treatments, and baseline CT scan signs in
patients with and without SHT, are reported in Tables 1
and 2
.
SHT was significantly more frequent in patients with atrial
fibrillation, diabetes mellitus, no heparin use, streptokinase
treatment, and early CT scan signs (hemispheric sulcus attenuation and
insular zone contrast attenuation; Figure 2
). The
multivariate model included streptokinase treatment,
diabetes mellitus, hemispheric sulcus attenuation, and the interaction
between a decreased level of consciousness and streptokinase treatment
(ie, the patients who had a decreased level of consciousness and were
treated with streptokinase). Within the streptokinase group, diabetes
mellitus, hemispheric sulcus attenuation, and decreased level of
consciousness were kept in the final model (Table 4
). The predictive model for SHT had 19%
sensitivity (95% CI, 15% to 24%), 99% specificity (95% CI, 98% to
100%), 78% positive predictive value (95% CI, 73% to 83%), 89%
negative predictive value (95% CI, 85% to 93%), and 89% efficiency
(95% CI, 85% to 93%).
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| Discussion |
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The rate of SHT has not been reported for all studies. After
thrombolysis for MI, 5 of 27 patients (19%) suffering
from an ischemic stroke developed SHT.28 In recent
series of patients treated with t-PA for acute ischemic stroke,
SHT occurred in 3.6% of 85 consecutive patients,27 9.6%
of 104 patients,30 5% of 100 patients32 and
7% of 30 patients.31 In controlled clinical trials of
thrombolysis for acute stroke, SHT ranged from 0.6% to
7% in the placebo group and from 6.4% to 20% in the thrombolyzed
group (Table 5
). In our study, the rates of total HT and SHT
were 43.7% and 2.6%, respectively, in the placebo group compared with
67.8% and 21.2% in the streptokinase group. The rates in the placebo
group are within the range of published rates of HT and SHT. In the
streptokinase group the rates of HT and SHT are higher than those in
the treatment groups of other acute stroke trials (Table 5
).
However, the rates of HT and SHT differed significantly from one study
to another. Such heterogeneity between trials in the
incidence of HT and SHT may result in part from sample fluctuations. In
each trial, the proportion of HT and SHT is small, and thus populations
of HT, and particularly SHT, are small. By chance, sample fluctuations
may result in major differences in HT and SHT rates. Potential biases
in the HT rate estimation also need to be addressed. First, a selection
bias related to the baseline characteristics of the patients, such as
geographic or ethnic factors, severity, mechanism (cardiac embolism
versus in situ thrombosis), topography of stroke (ICA versus MCA),
delay to inclusion, and time period over which the HT were evaluated
could have selected groups of patients with very different bleeding
risks. Second, biases in the care given to patients could have
occurred; for example, associated treatments were different between
studies. Third, classification biases such as the assessment of HT and
SHT may have occurred, because there is no shared criteria for the
assessment and classification of HT on CT. This is particularly true
for petechial HT.33 The classification of
hemorrhages as symptomatic or not may also be
controversial, because neurological deterioration may or may not be due
to HT. Using crude rates rather than relative risks to compare the
incidence of HT and SHT between these trials may be misleading. After
thrombolysis, the relative risks are ranged from
1.165 to 3.110 for HT and from
2.75 to 10.010 for SHT (Table 5
). No significant difference between streptokinase and
tPA in hemorrhagic risk can be evidenced. In controlled
thrombolytic trials for acute MI, an excessive number
of hemorrhagic strokes has been reported for tPA.34
Therefore, only a direct comparison of streptokinase and tPA in an
acute ischemic stroke trial could permit to assess the
difference in risk of bleeding between the 2 drugs.
Predictors of HT and SHT
In controlled thrombolysis trials for MI, risk
factors for HT have been reported to be low body
weight,29 35 elderly age,20 21 29 35
hypertension at admission,20 29 35 and
thrombolytic treatment assignment.29 35
Data for acute ischemic stroke are available from trials and
from clinical and autopsy series. In acute ischemic stroke
trials, body weight and hypertension have not been evidenced as risk
factors, but advanced age and tPA treatment were associated with
increased risk of parenchymal hemorrhage in
ECASS11 and of both SHT and total HT in the
NINDS.12 Other risk factors for SHT in acute stroke
thrombolytic studies include a cardioembolic mechanism
of stroke,11 28 31 prior MI,32 stroke
severity,12 size of infarct,22 and
early CT signs.12 31 In autopsy studies1 3
and recent clinical series without thrombolysis, HT was
associated with severity, cardioembolic mechanism of the
stroke27 and early CT signs.26
In our study, HT was predicted by both early CT signs and streptokinase treatment, whereas SHT was predicted by diabetes mellitus, early CT signs, streptokinase treatment and the interaction between streptokinase treatment and a decreased level of consciousness. When we ran the model of SHT among the streptokinase-treated patients, the same predictors remained. This suggests that streptokinase increases the risk of SHT among patients who would have presented with asymptomatic hemorrhage had the treatment been the placebo. This is consistent with data from ECASS I and ECASS II, in which tPA treatment was associated with an increased risk of parenchymal hemorrhage but not of hemorrhagic infarction.11 However, SHT has not been assessed in ECASS I.
The presence of early CT signs predicted both HT and SHT in the multivariate analysis, which is in agreement with other thrombolytic studies.11 12 31 32 In MAST-E, early CT signs were present in 63% of the patients, the same order of magnitude as the Australian Streptokinase Trial (57.7%) but higher than in MAST-I (4.7%), ECASS (31%),11 and the NINDS study (5%).12 Early CT signs are reported from 31% to 92% in series focused on early CT signs among patients with MCA ischemia, according to the delay from onset to CT scan (4 to 8 hours).14 15 16 36 37 38 39 These discrepancies may be related to the patient selection and to CT sign measurement biases. There were differences in the severity of stroke, in the delay from stroke onset to CT scan, in the criteria used for early CT signs assessment, and also in the quality of CT scans. Actually, the absence of shared definition of early CT signs and the subtle brain appearance changes they characterize may be important contributors to the discrepancies between the rates reported. This is supported by the low intraobserver and interobserver concordance14 40 for early CT sign assessment. Although important metrological and teaching efforts could be done to reach a high level of reliability,41 this emphasizes that a treatment based on such subtle signs might be very difficult to introduce into routine practice.
We found an association between stroke severity (MAST score of <20, or low level of consciousness) and SHT in univariate analyses, although it did not reach a level of significance. In the multivariate model, decreased level of consciousness was a predictor of SHT only in patients assigned to streptokinase. Stroke severity has been demonstrated to be a predictor for SHT in NINDS12 and for HI in ECASS.11 This confirms that patients with such conditions should not receive thrombolytic treatment.
Our data indicate that diabetes mellitus is associated with SHT. Hyperglycemia at baseline was associated with an increased risk of SHT in the NINDS trial,10 and history of diabetes mellitus was associated with parenchymal hematoma in a stroke series.26 Both hyperglycemia and diabetes were predictors of HT and SHT in tPA-treated patients.42 However, although diabetes mellitus is a well-known risk factor for ischemic stroke, whether it is a risk factor for hemorrhage has yet to be determined.2
Our univariate analysis showed a possible association between atrial fibrillation and both HT (P=0.12) and SHT (P=0.05). A relation between cardioembolic strokes and HT has been reported in autopsy studies1 3 in thrombolysis series,31 in ECASS,11 and in trials in MI.28 The high rate of cardioembolic stroke in the MAST-E population (30%) may have promoted a high rate of HT.
The high crude rates of HT and SHT in our streptokinase group could be
attributed to the heavy use of heparin or aspirin as associated
treatment within the first 48 hours. However, both heparin and aspirin
were associated with a low incidence of SHT (Table 3
). Moreover,
heparin administration appeared to be a predictor of low risk of SHT in
our multivariate analysis, suggesting a
paradoxical protective effect. Heparin appears to be an established
risk factor for HT in acute stroke.43 44 45 However, some
studies have not reported an increased risk of bleeding during heparin
treatment, either in association with thrombolytics in
a meta-analysis of trials for MI35 or
alone.46 Because heparin was not used randomly in MAST-E,
it is likely that early occurrence of HT prevented the investigator
from using antithrombotic drugs within the first hours. Therefore,
because we thought that including this variable in the model could
be misleading, we did not keep heparin treatment in our
multivariate models.
It has been suggested30 that a long delay from stroke onset to thrombolytic treatment is related to a high rate of SHT. We explored this hypothesis, but neither univariate nor multivariate analysis demonstrated any association between HT or SHT and a longer delay. These results are supported by findings from ECASS I and ECASS II, in which patients treated between 3 and 6 hours after stroke did not have a higher risk of parenchymal hemorrhage than those treated within the first 3 hours,11 and by the NINDS study,12 in which patients treated between 90 and 180 minutes did not have a higher risk of SHT than those treated within 90 minutes of onset.
To explore the dose effect in HT occurrence, because a fixed dose of streptokinase was used, we studied the relationship between HT and body weight. We found no relationship, but in a recent study fibrinolytic blood parameters were strongly correlated with the body mass index.47 These conflicting results suggest that the dose issue should be addressed further.
Conclusion
We report the post hoc analysis of a controlled clinical
trial using streptokinase in acute ischemic stroke (MAST-E). In
both the streptokinase and placebo groups, higher absolute rates of HT
and SHT than in other studies were found, but the relative risks of
streptokinase were in the same range as in other streptokinase and tPA
trials. Only a direct comparison of streptokinase and tPA in acute
ischemic stroke would allow assessment of the differential
effects of the 2 drugs. In addition, the issue of the dose of
streptokinase should be addressed before planning other trials with
streptokinase in acute stroke.
Through use of logistic regression analysis, early CT signs were identified as a strong predictor of both HT and SHT, stressing that this group of patients has a peculiarly high risk of bleeding. The precise role of diabetes mellitus in the occurrence of SHT must be assessed. Our results indicate that a decreased level of consciousness was a predictor of SHT in streptokinase-treated patients. This is consistent with the lower rate of SHT in studies that excluded patients with coma or stupor.5 9 10
| Acknowledgments |
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Received February 16, 1999; accepted March 30, 1999.
| References |
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