Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment

BACKGROUND AND PURPOSE

The etiology of ischemic stroke affects prognosis, outcome, and management. Trials of therapies for patients with acute stroke should include measurements of responses as influenced by subtype of ischemic stroke. A system for categorization of subtypes of ischemic stroke mainly based on etiology has been developed for the Trial of Org 10172 in Acute Stroke Treatment (TOAST).

METHODS

A classification of subtypes was prepared using clinical features and the results of ancillary diagnostic studies. "Possible" and "probable" diagnoses can be made based on the physician's certainty of diagnosis. The usefulness and interrater agreement of the classification were tested by two neurologists who had not participated in the writing of the criteria. The neurologists independently used the TOAST classification system in their bedside evaluation of 20 patients, first based only on clinical features and then after reviewing the results of diagnostic tests.

RESULTS

The TOAST classification denotes five subtypes of ischemic stroke: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) stroke of other determined etiology, and 5) stroke of undetermined etiology. Using this rating system, interphysician agreement was very high. The two physicians disagreed in only one patient. They were both able to reach a specific etiologic diagnosis in 11 patients, whereas the cause of stroke was not determined in nine.

CONCLUSIONS

The TOAST stroke subtype classification system is easy to use and has good interobserver agreement. This system should allow investigators to report responses to treatment among important subgroups of patients with ischemic stroke. Clinical trials testing treatments for acute ischemic stroke should include similar methods to diagnose subtypes of stroke.

Effect of intensity of oral anticoagulation on stroke severity and mortality in atrial fibrillation

BACKGROUND

The incidence of stroke in patients with atrial fibrillation is greatly reduced by oral anticoagulation, with the full effect seen at international normalized ratio (INR) values of 2.0 or greater. The effect of the intensity of oral anticoagulation on the severity of atrial fibrillation-related stroke is not known but is central to the choice of the target INR.

METHODS

We studied incident ischemic strokes in a cohort of 13,559 patients with nonvalvular atrial fibrillation. Strokes were identified through hospitalization data bases and validated on the basis of medical records, which also provided information on the use of warfarin or aspirin, the INR at admission, and coexisting illnesses. The severity of stroke was graded according to a modified Rankin scale. Thirty-day mortality was ascertained from hospitalization and mortality files.

RESULTS

Of 596 ischemic strokes, 32 percent occurred during warfarin therapy, 27 percent during aspirin therapy, and 42 percent during neither type of therapy. Among patients who were taking warfarin, an INR of less than 2.0 at admission, as compared with an INR of 2.0 or greater, independently increased the odds of a severe stroke in a proportional-odds logistic-regression model (odds ratio, 1.9; 95 percent confidence interval, 1.1 to 3.4) across three severity categories and the risk of death within 30 days (hazard ratio, 3.4; 95 percent confidence interval, 1.1 to 10.1). An INR of 1.5 to 1.9 at admission was associated with a mortality rate similar to that for an INR of less than 1.5 (18 percent and 15 percent, respectively). The 30-day mortality rate among patients who were taking aspirin at the time of the stroke was similar to that among patients who were taking warfarin and who had an INR of less than 2.0.

CONCLUSIONS

Among patients with nonvalvular atrial fibrillation, anticoagulation that results in an INR of 2.0 or greater reduces not only the frequency of ischemic stroke but also its severity and the risk of death from stroke. Our findings provide further evidence against the use of lower INR target levels in patients with atrial fibrillation.

Epidemiology of ischemic stroke subtypes according to TOAST criteria: incidence, recurrence, and long-term survival in ischemic stroke subtypes: a population-based study

BACKGROUND AND PURPOSE

The purpose of this study was to determine the incidence, recurrence, and long-term survival rates of ischemic stroke subtypes by a mechanism-based classification scheme (Trial of ORG 10172 in Acute Stroke Treatment, or TOAST).

METHODS

We identified all 583 residents of the city of Erlangen, Bavaria, Germany, with a first ischemic stroke between 1994 and 1998. Multiple overlapping sources of information were used to ensure completeness of case ascertainment. The cause of ischemic stroke was classified according to the TOAST criteria. Patients were followed up at 3 months and 1 and 2 years after stroke onset.

RESULTS

The age-standardized incidence rates for the European population (per 100 000) regarding ischemic stroke subtypes were as follows: cardioembolism, 30.2 (95% CI 25.6 to 35.7); small-artery occlusion, 25.8 (95% CI 21.5 to 30.9); and large-artery atherosclerosis, 15.3 (95% CI 12 to 19.3). When age-adjusted to the European population, the incidence rate for large-artery atherosclerosis was more than twice as high for men than for women (23.6/100 000 versus 9.2/100 000). Two years after onset, patients in the small-artery occlusion subgroup were 3 times more likely to be alive than those with cardioembolism. Ischemic stroke subtype according to the TOAST criteria was a significant predictor for long-term survival, whereas subtype was not a significant predictor of long-term recurrence up to 2 years, both before and after adjustment for age and sex.

CONCLUSIONS

Epidemiological observational studies that possess wide access to appropriate diagnostic technologies and apply standardized etiologic classifications provide a much better understanding of underlying risk factors for initial stroke, recurrence, and mortality.

Use of the Barthel index and modified Rankin scale in acute stroke trials

BACKGROUND AND PURPOSE

The Barthel Index (BI) and the Modified Rankin Scale (MRS) are commonly used scales that measure disability or dependence in activities of daily living in stroke victims. The objective of this study was to investigate how these scales were used and interpreted in acute stroke trials.

METHODS

We identified from MEDLINE the major efficacy trials with neuroprotective drugs, thrombolytic drugs, and anticoagulants in acute ischemic stroke published between January 1995 and December 1998. We selected those trials that used the BI and/or MRS as outcome parameters.

RESULTS

Fifteen trials fulfilling the inclusion criteria were identified. The BI was used in 13 and the MRS in 8. In 4 trials mean and median scores of the BI were used, and in 1 trial median scores of the MRS were compared. Primary end points included the BI in 7, the MRS in 6, and both the BI and MRS in 3. With regard to the BI, a variety of sum scores between 50 and 95 were used as cutoff scores to define favorable outcome. Favorable outcome on the MRS was defined as either </=1 or </=2.

CONCLUSIONS

Among the efficacy trials in acute stroke, we found remarkable differences in the choice of primary end points and in the definition of favorable outcome on both the BI and MRS. This lack of consensus strongly hinders the design, interpretation, and comparison of acute stroke trials. In general, it may be easier to define poor outcome instead of favorable outcome. Poor outcome could be defined if any of the following end points are reached: death, institutionalization due to stroke, MRS >3, or BI <60.

Ischemic stroke subtype incidence among whites, blacks, and Hispanics: the Northern Manhattan Study

BACKGROUND

Stroke incidence is greater in blacks than in whites; data on Hispanics are limited. Comparing subtype-specific ischemic stroke incidence rates may help to explain race-ethnic differences in stroke risk. The aim of this population-based study was to determine ischemic stroke subtype incidence rates for whites, blacks, and Hispanics living in one community.

METHODS AND RESULTS

A comprehensive stroke surveillance system incorporating multiple overlapping strategies was used to identify all cases of first ischemic stroke occurring between July 1, 1993, and June 30, 1997, in northern Manhattan. Ischemic stroke subtypes were determined according to a modified NINDS scheme, and age-adjusted, race-specific incidence rates calculated. The annual age-adjusted incidence of first ischemic stroke per 100,000 was 88 (95% CI, 75 to 101) in whites, 149 (95% CI, 132 to 165) in Hispanics, and 191 (95% CI, 160 to 221) in blacks. Among blacks compared with whites, the relative rate of intracranial atherosclerotic stroke was 5.85 (95% CI, 1.82 to 18.73); extracranial atherosclerotic stroke, 3.18 (95% CI, 1.42 to 7.13); lacunar stroke, 3.09 (95% CI, 1.86 to 5.11); and cardioembolic stroke, 1.58 (95% CI, 0.99 to 2.52). Among Hispanics compared with whites, the relative rate of intracranial atherosclerotic stroke was 5.00 (95% CI, 1.69 to 14.76); extracranial atherosclerotic stroke, 1.71 (95% CI, 0.80 to 3.63); lacunar stroke, 2.32 (95% CI, 1.48 to 3.63); and cardioembolic stroke, 1.42 (95% CI, 0.97 to 2.09).

CONCLUSIONS

The high ischemic stroke incidence among blacks and Hispanics compared with whites is due to higher rates of all ischemic stroke subtypes.

Validating administrative data in stroke research

BACKGROUND AND PURPOSE

Research based on administrative data has advantages, including large numbers, consistent data, and low cost. This study was designed to compare different methods of stroke classification using administrative data.

METHODS

Administrative hospital discharge data and medical record review of 206 patients were used to evaluate 3 algorithms for classifying stroke patients. These algorithms were based on all (algorithm 1), the first 2 (algorithm 2), or the primary (algorithm 3) administrative discharge diagnosis code(s). The diagnoses after review of medical record data were considered the gold standard. Then, using a large administrative data set, we compared patients with a primary discharge diagnosis of stroke with patients with their stroke discharge diagnosis code in a nonprimary position.

RESULTS

Compared with the gold standard, algorithm 1 had the highest kappa for classifying ischemic stroke, with a sensitivity of 86%, specificity of 95%, positive predictive value of 90%, and kappa=0.82. Algorithm 3 had the highest kappa values for intracerebral hemorrhage and subarachnoid hemorrhage. For intracerebral hemorrhage, the sensitivity was 85%, specificity was 96%, positive predictive value was 89%, and kappa=0.82. For subarachnoid hemorrhage, those values were 90%, 97%, 94%, and 0.88, respectively. Nonprimary position ischemic stroke patients had significantly greater comorbidity and 30-day mortality (odds ratio, 3.2) than primary position ischemic stroke patients.

CONCLUSIONS

Stroke classification in these administrative data were optimal using all discharge diagnoses for ischemic stroke and primary discharge diagnosis only for intracerebral and subarachnoid hemorrhage. Selecting ischemic stroke patients on the basis of primary discharge diagnosis may bias administrative samples toward more benign, unrepresentative outcomes and should be avoided.

Risk factors, outcome, and treatment in subtypes of ischemic stroke: the German stroke data bank

BACKGROUND AND PURPOSE

Data on risk factors for etiologic subtypes of ischemic stroke are still scant. The aim of this study was to characterize stroke subtypes regarding risk factor profile, outcome, and current treatment strategies.

METHODS

We analyzed data from 5017 patients with acute ischemic stroke (42.4% women, aged 65.9+/-14.1 years) who were enrolled in a large multicenter hospital-based stroke data bank. Standardized data assessment and stroke subtype classification were used by all centers.

RESULTS

Sex and age distribution, major risk factors and comorbidities, recurrent stroke, treatment strategies, and outcome were all unevenly distributed among stroke subtypes (P<0.001, respectively). Cardioembolism, the most frequent etiology of stroke (25.6%), was particularly common in the elderly (those aged >70 years) and associated with an adverse outcome, a low rate of early stroke recurrence, and frequent use of thrombolytic therapy and intravenous anticoagulation. Large-artery atherosclerosis (20.9%), the most common cause of stroke in middle-aged patients (those aged 45 to 70 years), showed the highest male preponderance, highest rate of early stroke recurrence, and highest prevalence of previous transient ischemic attack, current smoking, and daily alcohol consumption among all subtypes. The highest prevalence of hypertension, diabetes mellitus, hypercholesterolemia, and obesity was found in small-vessel disease (20.5%), which, in turn, was associated with the lowest stroke severity and mortality.

CONCLUSIONS

Our results foster the concept of ischemic stroke as a polyetiologic disease with marked differences between subtypes regarding risk factors and outcome. Therefore, studies involving risk factors of ischemic stroke should differentiate between etiologic stroke subtypes.

Early risk of recurrence by subtype of ischemic stroke in population-based incidence studies

OBJECTIVE

To study the early risk of recurrent stroke by etiologic subtype.

METHODS

The authors studied risk of recurrent stroke by etiologic subtype (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] classification) in patients in two population-based studies: the Oxford Vascular Study and the Oxfordshire Community Stroke Project. A meta-analysis was performed with data from the only two other published studies reporting equivalent data.

RESULTS

The four studies included 1,709 strokes with 30 recurrences at 7 days, 72 at 30 days, and 113 at 3 months. Recurrent stroke risk varied between subtypes (p < 0.001). Compared with other subtypes, patients with stroke due to large-artery atherosclerosis (LAA) had the highest odds of recurrence at 7 days (odds ratio [OR] = 3.3, 95% CI = 1.5 to 7.0), 30 days (OR = 2.9, 95% CI = 1.7 to 4.9), and 3 months (OR = 2.9, 95% CI = 1.9 to 4.5). Odds of recurrence at 30 days for other subtypes were cardioembolic (OR = 1.0, 95% CI = 0.6 to 1.7), undetermined (OR = 1.0, 95% CI = 0.6 to 1.6), and small-vessel stroke (OR = 0.2, 95% CI = 0.1 to 0.6). There was no significant heterogeneity between the studies. Although only 14% of strokes were associated with LAA, this subtype accounted for 37% of recurrences within 7 days.

CONCLUSIONS

The risk of early recurrent stroke is highest in patients with LAA. This supports the need for urgent carotid imaging and prompt endarterectomy.

Effects of tissue plasminogen activator for acute ischemic stroke at one year. National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Stroke Study Group

BACKGROUND

In 1995, the two-part National Institute of Neurological Disorders and Stroke (NINDS) Recombinant Tissue Plasminogen Activator Stroke Trial found that patients who were treated with tissue plasminogen activator (t-PA) within three hours after the onset of symptoms of acute ischemic stroke were at least 30 percent more likely than patients given placebo to have minimal or no disability three months after the stroke. It was unknown, however, whether the benefit would be sustained for longer periods.

METHODS

In the NINDS Trial, a total of 624 patients with stroke were randomly assigned to receive either t-PA or placebo. We collected outcome data over a period of 12 months after the occurrence of stroke. The primary outcome measure was a "favorable outcome," defined as minimal or no disability as measured by the Barthel index, the modified Rankin Scale, and the Glasgow Outcome Scale. We assessed the treatment effect using a global statistic.

RESULTS

Using an intention-to-treat analysis for the combined results of the two parts of the trial at 6 months and 12 months, we found that the global statistic favored the t-PA group (odds ratio for a favorable outcome at 6 months, 1.7; 95 percent confidence interval, 1.3 to 2.3; odds ratio at 12 months, 95 percent confidence interval, 1.7; 1.2 to 2.3). The patients treated with t-PA were at least 30 percent more likely to have minimal or no disability at 12 months than were the placebo-treated patients (absolute increase in the proportion with a favorable outcome, 11 to 13 percentage points). There was no significant difference in mortality at 12 months between the t-PA group and the placebo group (24 percent vs. 28 percent, P=0.29). There was no interaction between the type of stroke identified at base line and treatment with respect to the long-term response. The rate of recurrent stroke at 12 months was similar in the two groups.

CONCLUSIONS

During 12 months of follow-up, the patients with acute ischemic stroke who were treated with t-PA within three hours after the onset of symptoms were more likely to have minimal or no disability, than the patients given placebo. These results indicate a sustained benefit of t-PA for such patients.

A Computerized Algorithm for Etiologic Classification of Ischemic Stroke

Background and Purpose— The SSS-TOAST is an evidence-based classification algorithm for acute ischemic stroke designed to determine the most likely etiology in the presence of multiple competing mechanisms. In this article, we present an automated version of the SSS-TOAST, the Causative Classification System (CCS), to facilitate its utility in multicenter settings.

Methods— The CCS is a web-based system that consists of questionnaire-style classification scheme for ischemic stroke (http://ccs.martinos.org). Data entry is provided via checkboxes indicating results of clinical and diagnostic evaluations. The automated algorithm reports the stroke subtype and a description of the classification rationale. We evaluated the reliability of the system via assessment of 50 consecutive patients with ischemic stroke by 5 neurologists from 4 academic stroke centers.

Results— The kappa value for inter-examiner agreement was 0.86 (95% CI, 0.81 to 0.91) for the 5-item CCS (large artery atherosclerosis, cardio-aortic embolism, small artery occlusion, other causes, and undetermined causes), 0.85 (95% CI, 0.80 to 0.89) with the undetermined group broken into cryptogenic embolism, other cryptogenic, incomplete evaluation, and unclassified groups (8-item CCS), and 0.80 (95% CI, 0.76 to 0.83) for a 16-item breakdown in which diagnoses were stratified by the level of confidence. The intra-examiner reliability was 0.90 (0.75–1.00) for 5-item, 0.87 (0.73–1.00) for 8-item, and 0.86 (0.75–0.97) for 16-item CCS subtypes.

Conclusions— The web-based CCS allows rapid analysis of patient data with excellent intra- and inter-examiner reliability, suggesting a potential utility in improving the fidelity of stroke classification in multicenter trials or research databases in which accurate subtyping is critical.

Age and National Institutes of Health Stroke Scale Score within 6 hours after onset are accurate predictors of outcome after cerebral ischemia: development and external validation of prognostic models

BACKGROUND AND PURPOSE

To date, no validated, comprehensive, and practicable model exists to predict functional recovery within the first hours of cerebral ischemic symptoms. The purpose of this study was to externally validate 2 prognostic models predicting functional outcome and survival at 100 days within the first 6 hours after onset of acute cerebral ischemia.

METHODS

On admission to a participating hospital, patients were registered prospectively and included according to defined criteria. Follow-up was performed 100 days after the event. With the use of prospectively collected data, 2 prognostic models were developed and internally calibrated in 1079 patients and externally validated in 1307 patients. By means of age and National Institutes of Health Stroke Scale (NIHSS) score as independent variables, model I predicts incomplete functional recovery (Barthel Index <95) versus complete functional recovery, and model II predicts mortality versus survival.

RESULTS

In the validation data set, model I correctly predicted 62.9% of the patients who were incompletely restituted or had died and 83.2% of the completely restituted patients, and model II correctly predicted 57.9% of the patients who had died and 91.5% of the surviving patients. Both models performed better than the treating physicians' predictions made within 6 hours after admission.

CONCLUSIONS

The resulting prognostic models are useful to correctly stratify treatment groups in clinical trials and should guide inclusion criteria in clinical trials, which in turn increases the power to detect clinically relevant differences.

The value of a scoring system for hypoxic ischaemic encephalopathy in predicting neurodevelopmental outcome

A numeric scoring system for the assessment of hypoxic ischaemic encephalopathy during the neonatal period was tested. The value of the score in predicting neurodevelopmental outcome at 1 y of age was assessed. Forty-five infants who developed hypoxic ischaemic encephalopathy after birth were studied prospectively. In addition to the hypoxic ischaemic encephalopathy score all but two infants had at least one cranial ultrasound examination. Thirty-five infants were evaluated at 12 months of age by full neurological examination and the Griffiths Scales of Mental Development. Five infants were assessed at an earlier stage, four who died before 6 months of age and one infant who was hospitalized at the time of the 12 month assessment. Twenty-three (58%) of the infants were normal and 17 (42%) were abnormal, 16 with cerebral palsy and one with developmental delay. The hypoxic ischaemic encephalopathy score was highly predictive for outcome. The best correlation with outcome was the peak score; a peak score of 15 or higher had a positive predictive value of 92% and a negative predictive value of 82% for abnormal outcome, with a sensitivity and specificity of 71% and 96%, respectively. For the clinician working in areas where sophisticated technology is unavailable this scoring system will be useful for assessment of infants with hypoxic ischaemic encephalopathy and for prognosis of neurodevelopmental outcome.

Animal models of focal and global cerebral ischemia

The use of appropriate animal models is essential to predict the value and effect of therapeutic approaches in human subjects. Focal (stroke) and global (cardiac arrest) cerebral ischemia represents diseases that are common in the human population. Stroke and cardiac arrest, which are major causes of death and disability, affect millions of individuals around the world and are responsible for the leading health care costs of all diseases. Understanding the mechanisms of injury and neuroprotection in these diseases is critical if we are ever to learn new target sites to treat ischemia. There are many animal models available to investigate injury mechanisms and neuroprotective strategies. This review summarizes many (but not all) small and large animal models of focal and global cerebral ischemia and discusses their advantages and disadvantages.

Risk Factors for Ischemic Stroke Subtypes

BACKGROUND AND PURPOSE

To evaluate risk factors for ischemic stroke by its subtypes may contribute to more effective prevention of ischemic stroke, but few prospective studies have characterized risk factors for specific subtypes of ischemic stroke.

METHODS

Between 1987 and 1989, 14,448 men and women aged 45 to 64 years and free of clinical stroke took part in the first examination of the Atherosclerosis Risk in Communities study. The incidence of stroke was ascertained from hospital surveillance records.

RESULTS

During an average follow-up of 13.4-years, 531 incident ischemic strokes occurred (105 lacunar, 326 nonlacunar, and 100 cardioembolic). Blacks had a 3-fold higher multivariate-adjusted risk ratio of lacunar stroke compared with whites. No racial difference in nonlacunar or cardioembolic strokes was found after adjusting for prevalent risk factors. In addition to traditional risk factors, nontraditional risk factors, such as waist-to-hip ratio, history of coronary heart disease, left ventricular hypertrophy, lipoprotein(a), and von Willebrand factor, were associated with increased risk for nonlacunar stroke, whereas lacunar stroke was related to only 1 nontraditional risk factor, white blood cell count. The population-attributable fraction (PAF) for hypertension was approximately 35% for all ischemic stroke subtypes. The respective PAFs for diabetes and current smoking were 26.3% and 22.0% for lacunar versus 11.3% and 11.4% for nonlacunar stroke. The PAF for elevated von Willebrand factor was greater than that for current smoking for cardioembolic stroke.

CONCLUSIONS

The impact of traditional and nontraditional risk factors other than hypertension on the incidence of ischemic stroke varied according to its subtype.

Inaccuracy of the International Classification of Diseases (ICD-9-CM) in identifying the diagnosis of ischemic cerebrovascular disease

In administrative databases the International Classification of Diseases, Version 9, Clinical Modification (ICD-9-CM) is often used to identify patients with specific diagnoses. However, certain conditions may not be accurately reflected by the ICD-9 codes. We assessed the accuracy of ICD-9 coding for cerebrovascular disease by comparing ICD-9 codes in an administrative database with clinical findings ascertained from medical record abstractions. We selected patients with ICD-9 diagnostic codes of 433 through 436 (in either the primary or secondary positions) from an administrative database of patients hospitalized in five academic medical centers in 1992. Medical records of the selected patients were reviewed by trained medical abstractors, and the patients' clinical conditions during the admission (stroke, TIA, asymptomatic) were recorded, as well as any history of cerebrovascular symptoms. Results of the medical record review were compared with the ICD-9 codes from the administrative database. More than 85% of those patients with the ICD-9 code 433 were asymptomatic for the index admission. More than one-third of these asymptomatic patients did not undergo either cerebral angiography or carotid endarterectomy. For ICD-9 code 434, 85% of patients were classified as having a stroke and for ICD-9 code 435, 77% had TIAs. For code 436, 77% of patients were classified as having strokes. Limiting the identifying ICD-9 code to the primary position increased the likelihood of agreement with the medical record review. The ICD-9 coding scheme may be inaccurate in the classification of patients with ischemic cerebrovascular disease. Its limitations must be recognized in the analyses of administrative databases selected by using ICD-9 codes 433 through 436.

Differences in vascular risk factors between etiological subtypes of ischemic stroke: importance of population-based studies

BACKGROUND

To understand the mechanisms of stroke and to target prevention, we need to know how risk factors differ between etiological subtypes. Hospital-based studies may be biased because not all stroke patients are admitted. If risk factors differ between patients who are admitted and those who are not, then case-control studies will be biased. If the likelihood of admission also depends on stroke subtype, then case-case comparisons may also be biased.

METHODS

We compared risk factors and ischemic stroke subtypes (TOAST classification) in hospitalized and nonhospitalized patients in 2 population-based stroke incidence studies: the Oxford Vascular Study (OXVASC) and Oxfordshire Community Stroke Project (OCSP). We also performed a meta-analysis of risk factor-stroke subtype associations with other published population-based studies.

RESULTS

In OXVASC and OCSP, stroke subtypes differed between hospitalized (293 of 647) and nonhospitalized patients (P<0.0001), with more cardioembolic strokes (odds ratio [OR], 1.8; 95% CI, 1.3 to 2.6) and fewer lacunar strokes (OR, 0.4; 95% CI, 0.3 to 0.7). Premorbid blood pressure and cholesterol were higher in hospitalized patients (both P<0.0001). Risk factor-stroke subtype associations in hospitalized patients were consequently biased (P=0.001). Meta-analysis of data from all patients in OXVASC, OCSP, and 2 other studies demonstrated consistent risk factor-stroke subtype associations. However, contrary to previous hospital-based studies, there was only a weak (OR, 1.4; 95% CI, 1.1 to 1.8) and inconsistent (P(heterogeneity)=0.01) association between small-vessel stroke and hypertension and no association with diabetes (OR, 1.0; 95% CI, 0.7 to 1.3).

CONCLUSIONS

Prevalences of risk factors and stroke subtypes differ between hospitalized and nonhospitalized patients with ischemic stroke, which may bias hospital-based risk factor studies. Meta-analysis of population-based studies suggests that vascular risk factors differ between stroke subtypes.

Thrombolysis in brain ischemia (TIBI) transcranial Doppler flow grades predict clinical severity, early recovery, and mortality in patients treated with intravenous tissue plasminogen activator

BACKGROUND AND PURPOSE

TIMI angiographic classification measures coronary residual flow and recanalization. We developed a Thrombolysis in Brain Ischemia (TIBI) classification by using transcranial Doppler (TCD) to noninvasively monitor intracranial vessel residual flow signals. We examined whether the emergent TCD TIBI classification correlated with stroke severity and outcome in patients treated with intravenously administered tPA (IV-tPA).

METHODS

TCD examination occurred acutely and on day 2. TIBI flows were determined at distal MCA and basilar artery depths, depending on occlusion site. TIBI waveforms were graded as follows: 0, absent; 1, minimal; 2, blunted; 3, dampened; 4, stenotic; and 5, normal. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and 24 hours after administration of tPA.

RESULTS

One hundred nine IV tPA patients were studied. Mean+/-SD age was 68+/-16 years; median NIHSS score before administration of tPA (pre-tPA) was 17.5. The tPA bolus was administered 143+/-58 minutes and the TCD examination 141+/-57 minutes after symptom onset. Pre-tPA NIHSS scores were higher in patients with TIBI grade 0 than TIBI grade 4 or 5 flow. TIBI flow improvement to grade 4 or 5 occurred in 35% of patients (19/54) with an initial grade of 0 or 1 and in 52% (12/23) with initial grade 2 or 3. The 24-hour NIHSS scores were higher in follow-up in patients with TIBI grade 0 or 1 than those with TIBI grade 4 or 5 flow. TIBI flow recovery correlated with NIHSS score improvement. Lack of flow recovery predicted worsening or no improvement. In-hospital mortality was 71% (5/7) for patients with posterior circulation occlusions; it was 22% (11/51) for patients with pre-tPA TIBI 0 or 1 compared with 5% (1/19) for those with pre-tPA TIBI 2 or 3 anterior circulation occlusions.

CONCLUSIONS

Emergent TCD TIBI classification correlates with initial stroke severity, clinical recovery, and mortality in IV-tPA-treated stroke patients. A flow-grade improvement correlated with clinical improvement.

Association of Ischemic Lesion Patterns on Early Diffusion-Weighted Imaging With TOAST Stroke Subtypes

BACKGROUND

Different topographic patterns in patients who experience an acute ischemic stroke may be related to specific stroke causes.

OBJECTIVE

To determine if lesion patterns on early diffusion-weighted imaging (DWI) are associated with stroke subtypes determined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) classification.

DESIGN

Cross-sectional study.

SETTING

General community hospital. Patients We studied 172 consecutive ischemic stroke patients with a symptomatic lesion on DWI performed within 24 hours of stroke onset.

MAIN OUTCOME MEASURES

Lesion patterns on DWI were classified into single lesions (corticosubcortical, cortical, subcortical > or =15 mm, or subcortical <15 mm), scattered lesions in one vascular territory (small scattered lesions or confluent with additional lesions), and multiple lesions in multiple vascular territories (in the unilateral anterior circulation, in the posterior circulation, in bilateral anterior circulations, or in anterior and posterior circulations).

RESULTS

We found an overall significant relationship between DWI lesion patterns and TOAST stroke subtypes (P<.001). Corticosubcortical single lesions (P =.01), multiple lesions in anterior and posterior circulations (P =.03), and multiple lesions in multiple cerebral circulations (P =.008) were associated with cardioembolism. Multiple lesions in the unilateral anterior circulation (P =.04) and small scattered lesions in one vascular territory (P =.06) were related to large-artery atherosclerosis. Nearly half (11/23) of the patients with a single subcortical lesion that was 15 mm or larger were classified as having cryptogenic strokes (P =.001), although 9 of these patients had a classic lacunar syndrome without cortical hypoperfusion.

CONCLUSIONS

Early DWI lesion patterns are associated with specific stroke causes. Conventional 15-mm criteria for lacunes, however, may underestimate the diagnosis of small-vessel occlusion with DWI.

Serial assessment of acute stroke using the NIH Stroke Scale

BACKGROUND AND PURPOSE

The National Institutes of Health (NIH) Stroke Scale has been used in clinical trials to assess neurological outcome after investigational therapy for acute stroke. We used the NIH Stroke Scale to study the degree and time course of recovery in patients with acute stroke who were treated with conventional therapy.

METHODS

We serially assessed 50 patients with ischemic stroke who presented within 24 hours of onset of symptoms. Patients were grouped by stroke subtype. Major neurological improvement was defined as a decrease in the stroke score by 4 points or more.

RESULTS

The mean NIH stroke score for all patients improved significantly by 7 to 10 days and at last follow-up (average, 44 days). Major neurological improvement was seen in 5 of 41 patients (12%; 95% confidence interval [CI], 2% to 22%) by 24 hours, 11 of 40 patients (28%; 95% CI, 14% to 41%) by 48 hours, and 19 of 37 patients (51%; 95% CI, 35% to 67%) by follow-up. The subgroup of patients with middle cerebral artery territory embolism showed a similar pattern of improvement; in contrast, patients with lacunar infarcts did not show significant change in scores during the study period. The score on admission did not correlate with the degree of subsequent improvement or deterioration.

CONCLUSIONS

A significant percentage of patients with acute ischemic stroke treated with conventional therapy show early improvement as assessed by the NIH Stroke Scale. The degree and time course of recovery may be influenced by stroke type.

Evaluating the genetic component of ischemic stroke subtypes: a family history study

BACKGROUND AND PURPOSE

Twin and family history studies support a role for genetic factors in stroke risk. Because the etiology of ischemic stroke is heterogeneous, genetic factors may vary by etiologic subtype. We determined the familial aggregation of stroke risk in different stroke phenotypes and used the results to model estimated sample size requirements for case-control studies.

METHODS

One thousand consecutive white subjects with ischemic stroke and 800 white controls matched for age and sex were recruited. A first-degree family history of stroke and myocardial infarction was obtained by structured interview. Stroke subtype was determined with the use of modified Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria.

RESULTS

A family history of stroke at < or =65 years was a significant risk factor for large-vessel disease (odds ratio [OR], 2.24; 95% CI, 1.49 to 3.36; P<0.001) and for small-vessel disease (OR, 1.93; 95% CI, 1.25 to 2.97; P=0.003). When only cases aged <or =65 years were considered, these ORs increased to 2.93 (95% CI, 1.68 to 5.13) (P<0.001) and 3.15 (95% CI, 1.81 to 5.50) (P<0.001), respectively. No significant associations were seen for cardioembolic stroke or stroke of undetermined etiology.

CONCLUSIONS

A family history of vascular disease is an independent risk factor for both large-vessel atherosclerosis and small-vessel disease, especially in cases presenting before age 65 years. The estimated sample sizes for case-control studies illustrate how candidate gene studies for ischemic stroke might be made more effective by focusing on these specific phenotypes, in which the genetic component of the disease appears to be strongest.

Swallowing after unilateral stroke of the cerebral cortex

We report differential patterns of swallowing in 40 patients with their first ischemic middle cerebral artery (MCA) stroke and compare these to 20 nonstroke controls. Stroke patients were divided a priori, into groups by right or left and, post hoc, primarily anterior or posterior MCA territory lesions. The left hemisphere subgroup was differentiated from controls by longer pharyngeal transit durations and from the right hemisphere group by shorter pharyngeal response durations. The right hemisphere subgroup was characterized by longer pharyngeal stage durations and higher incidences of laryngeal penetration and aspiration of liquid. Anterior lesion subjects demonstrated significantly longer swallowing durations on most variables compared to both normal and posterior lesion subjects. Changes in the consistency of foods and other modifications for safe nutrition should be considered during the first month of recovery for unilateral stroke patients with swallowing difficulty.

PET imaging of cerebral perfusion and oxygen consumption in acute ischaemic stroke: relation to outcome

We used positron emission tomography (PET) to assess the relation between combined imaging of cerebral blood flow and oxygen consumption 5-18 h after first middle cerebral artery (MCA) stroke and neurological outcome at 2 months. All 18 patients could be classified into three visually defined PET patterns of perfusion and oxygen consumption changes. Pattern I (7 patients) suggested extensive irreversible damage and was consistently associated with poor outcome. Pattern II (5) suggested continuing ischaemia and was associated with variable outcome. Pattern III (6), with hyperperfusion and little or no metabolic alteration, was associated with excellent recovery, which suggests that early reperfusion is beneficial. This relation between PET and outcome was highly significant (p < 0.0005). The results suggest that within 5-18 h of stroke onset, PET is a good predictor of outcome in patterns I and III, for which therapy seems limited. The absence of predictive value for pattern II suggests that it is due to a reversible ischaemic state that is possibly amenable to therapy. These findings may have important implications for acute MCA stroke management and for patients' selection for therapeutic trials.

Current practice and future directions in the diagnosis and acute treatment of ischaemic stroke

Even though stroke presents as a variety of clinical syndromes, neuroimaging is the most important biomarker to help differentiate between stroke subtypes and assess treatment eligibility. Therapeutic advances have led to intravenous thrombolysis with tissue-type plasminogen activator and endovascular treatment for proximal vessel occlusion in the anterior cerebral circulation being standard care for acute ischaemic stroke. Providing access to this care has implications for existing systems of care for stroke and their organisation and has reintroduced the possibility of adjuvant and neuroprotective treatment strategies in acute ischaemic stroke. The use of neuroimaging for patient selection and speed of diagnosis and delivery of treatment are the dominant themes of modern ischaemic stroke care.

Comparison of Clinical Characteristics and Functional Outcomes of Ischemic Stroke in Different Vascular Territories

BACKGROUND AND PURPOSE

We aim to compare demographics and functional outcomes of patients with stroke in a variety of vascular territories who underwent inpatient rehabilitation. Such comparative data are important in functional prognostication, rehabilitation, and healthcare planning, but literature is scarce and isolated.

METHODS

Using data collected prospectively over a 9-year period, we studied 2213 individuals who sustained first-ever ischemic strokes and were admitted to an inpatient stroke rehabilitation program. Strokes were divided into anterior cerebral artery, middle cerebral artery (MCA), posterior cerebral artery, brain stem, cerebellar, small-vessel strokes, and strokes occurring in more than one vascular territory. The main functional outcome measure was the Functional Independence Measure (FIM). Repeated-measures analysis of covariance with post hoc analyses was used to compare functional outcomes of the stroke groups.

RESULTS

The most common stroke groups were MCA stroke (50.8%) and small-vessel stroke (12.8%). After adjustments for age, gender, risk factors, and admission year, the stroke groups can be arranged from most to least severe disability on admission: strokes in more than one vascular territory, MCA, anterior cerebral artery, posterior cerebral artery, brain stem, cerebellar, and small-vessel strokes. The sequence was similar on discharge, except cerebellar strokes had the least disability rather than small-vessel strokes. Hemispheric (more than one vascular territory, MCA, anterior cerebral artery, posterior cerebral artery) strokes collectively have significantly lower admission and discharge total and cognitive FIM scores compared with the other stroke groups. MCA stroke had the lowest FIM efficiency and cerebellar stroke the highest. Regardless, patients with stroke made significant (P<0.001) and approximately equal (P=0.535) functional gains in all groups. Higher admission motor and cognitive FIM scores, longer rehabilitation stay, younger patients, lower number of medical complications, and a year of admission after 2000 were associated with higher discharge total FIM scores on multiple regression analysis.

CONCLUSIONS

Patients with stroke made significant functional gains and should be offered rehabilitation regardless of stroke vascular territory. The initial functional status at admission, rather than the stroke subgroup, better predicts discharge functional outcomes postrehabilitation.

Comparison of 30-day mortality models for profiling hospital performance in acute ischemic stroke with vs without adjustment for stroke severity

CONTEXT

There is increasing interest in reporting risk-standardized outcomes for Medicare beneficiaries hospitalized with acute ischemic stroke, but whether it is necessary to include adjustment for initial stroke severity has not been well studied.

OBJECTIVE

To evaluate the degree to which hospital outcome ratings and potential eligibility for financial incentives are altered after including initial stroke severity in a claims-based risk model for hospital 30-day mortality for acute ischemic stroke.

DESIGN, SETTING, AND PATIENTS

Data were analyzed from 782 Get With The Guidelines-Stroke participating hospitals on 127,950 fee-for-service Medicare beneficiaries with ischemic stroke who had a score documented for the National Institutes of Health Stroke Scale (NIHSS, a 15-item neurological examination scale with scores from 0 to 42, with higher scores indicating more severe stroke) between April 2003 and December 2009. Performance of claims-based hospital mortality risk models with and without inclusion of NIHSS scores for 30-day mortality was evaluated and hospital rankings from both models were compared.

MAIN OUTCOMES MEASURES

Model discrimination, hospital 30-day mortality outcome rankings, and value-based purchasing financial incentive categories.

RESULTS

Across the study population, the mean (SD) NIHSS score was 8.23 (8.11) (median, 5; interquartile range, 2-12). There were 18,186 deaths (14.5%) within the first 30 days, including 7430 deaths (5.8%) during the index hospitalization. The hospital mortality model with NIHSS scores had significantly better discrimination than the model without (C statistic, 0.864; 95% CI, 0.861-0.867, vs 0.772; 95% CI, 0.769-0.776; P < .001). Among hospitals ranked in the top 20% or bottom 20% of performers by the claims model without NIHSS scores, 26.3% were ranked differently by the model with NIHSS scores. Of hospitals initially classified as having "worse than expected" mortality, 57.7% were reclassified to "as expected" by the model with NIHSS scores. The net reclassification improvement (93.1%; 95% CI, 91.6%-94.6%; P < .001) and integrated discrimination improvement (15.0%; 95% CI, 14.6%-15.3%; P < .001) indexes both demonstrated significant enhancement of model performance after the addition of NIHSS. Explained variance and model calibration was also improved with the addition of NIHSS scores.

CONCLUSION

Adding stroke severity as measured by the NIHSS to a hospital 30-day risk model based on claims data for Medicare beneficiaries with acute ischemic stroke was associated with considerably improved model discrimination and change in mortality performance rankings for a substantial portion of hospitals.