Systematic review and pooled analysis of published and unpublished validations of the ABCD and ABCD2 transient ischemic attack risk scores

Effects of endovascular recanalization on symptomatic non-acute occlusion of intracranial arteries

To investigate the effect and safety of recanalization surgery for non-acute occlusion of large intracranial arteries and factors affecting clincial outcomes. Patients with non-acute occlusion of internal carotid artery (ICA), middle cerebral artery (MCA), and vertebrobasilar artery (VBA) treated with recanalization were retrospectively enrolled. The clinical and angiographic data were analyzed. 177 patients were enrolled, including 67 patients with intracranial ICA occlusion, 52 with MCA occlusion, and 58 with VBA occlusion. Successful recanalization was achieved in 152 (85.9%) patients. Complications occurred in 15 patients (8.5%). Followed up for 3-7 months, the 90 day mRS was significantly improved compared with that before the procedure. Among 152 patients with successful recanalization, eight patients experienced reocclusion (5.3%), and 11 patients experienced restenosis (7.2%). Successful recanalization was significantly (P < 0.05) associated with occlusion duration, calcification or angulation of the occluded segment. Complications were significantly (P < 0.05) associated with location of occlusion, hyperlipidemia, and patients' height. Restentosis or reocclusion at follow-up was significantly (P < 0.05) associated with complications and mRS at 90 days. The significant (P < 0.05) independent risk factors were angulation and calcification for successful recanalization, hyperlipidemia for complications, and mRS at 90 days for restenosis or reocclusion at follow-up. Recanalization surgery may be a safe and effective approach for patients with non-acute symptomatic occlusion of large intracranial arteries, and factors significantly independently associated with successful recanalization, periprocedural complications and restenosis or reocclusion after surgery have been identified for future reference to improve clinical outcomes.

Identifying transient ischemic attack (TIA) patients at high-risk of adverse outcomes: development and validation of an approach using electronic health record data

Background

Risk-stratification tools that have been developed to identify transient ischemic attack (TIA) patients at risk of recurrent vascular events typically include factors which are not readily available in electronic health record systems. Our objective was to evaluate two TIA risk stratification approaches using electronic health record data.

Methods

Patients with TIA who were cared for in Department of Veterans Affairs hospitals (October 2015—September 2018) were included. The six outcomes were mortality, recurrent ischemic stroke, and the combined endpoint of stroke or death at 90-days and 1-year post-index TIA event. The cohort was split into development and validation samples. We examined the risk stratification of two scores constructed using electronic health record data. The Clinical Assessment Needs (CAN) score is a validated measure of risk of hospitalization or death. The PREVENT score was developed specifically for TIA risk stratification.

Results

A total of N = 5250 TIA patients were included in the derivation sample and N = 4248 in the validation sample. The PREVENT score had higher c-statistics than the CAN score across all outcomes in both samples. Within the validation sample the c-statistics for the PREVENT score were: 0.847 for 90-day mortality, 0.814 for 1-year mortality, 0.665 for 90-day stroke, and 0.653 for 1-year stroke, 0.699 for 90-day stroke or death, and 0.744 for 1-year stroke or death. The PREVENT score classified patients into categories with extreme nadir and zenith outcome rates. The observed 1-year mortality rate among validation patients was 7.1%; the PREVENT score lowest decile of patients had 0% mortality and the highest decile group had 30.4% mortality.

Conclusions

The PREVENT score had strong c-statistics for the mortality outcomes and classified patients into distinct risk categories. Learning healthcare systems could implement TIA risk stratification tools within electronic health records to support ongoing quality improvement.

Registration

ClinicalTrials.gov Identifier: NCT02769338.

Clinical risk scores for stroke correlate with molecular signatures of vulnerability in symptomatic carotid patients

Unstable carotid stenosis is an important cause of ischemic stroke, yet the basis of disease pathophysiology remains largely unknown. We hypothesized that integrated analyses of symptomatic carotid stenosis patients at increased stroke risk stratified by clinical scores, CAR and ABCD2, with transcriptomic and clinical data could improve identification of molecular pathways and targets for instability. We show that high CAR score reflects plaque instability processes related to intra-plaque hemorrhage, angiogenesis, inflammation, and foam cell differentiation, whereas ABCD2 associates with neutrophil-mediated immunity, foam cell differentiation, cholesterol transport, and coagulation. Repressed processes in plaques from high-risk patients were ossification, chondrocyte differentiation, SMC migration, and ECM organization. ABCB5 gene was found as the top upregulated in high-risk patient’s plaques, localized to macrophages in areas with neovascularization and intra-plaque hemorrhage. The link between ABCB5 and intra-plaque hemorrhage suggests its key role for plaque instability that warrants further exploration.

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We integrated stroke risk in carotid stenosis patients with plaque transcriptomics

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High CAR and ABCD2 scores reflect plaque instability processes and hemorrhage

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ABCB5 is upregulated in high-risk plaques, macrophages, and around neovessels

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CAR and ABCD2 capture vulnerable plaque features and improve risk stratification

The Cognitive Sequelae of Transient Ischemic Attacks—Recent Insights and Future Directions

There is now considerable evidence that Transient Ischemic Attack (TIA) carries important sequelae beyond the risk of recurrent stroke, particularly with respect to peri-event and post-event cognitive dysfunction and subsequent cognitive decline. The occurrence of a TIA could provide an important window in understanding the relationship of early mixed vascular-neurodegenerative cognitive decline, and by virtue of their clinical relevance as a “warning” event, TIAs could also furnish the opportunity to act preventatively not only for stroke prevention but also for dementia prevention. In this review, we discuss the current state of the literature regarding the cognitive sequelae associated with TIA, reviewing important challenges in the field. In particular, we discuss definitional and methodological challenges in the study of TIA-related cognitive impairment, confounding factors in the cognitive evaluation of these patients, and provide an overview of the evidence on both transient and long-term cognitive impairment after TIA. We compile recent insights from clinical studies regarding the predictors and mediators of cognitive decline in these patients and highlight important future directions for work in this area.

Treating High-Risk TIA and Minor Stroke Patients With Dual Antiplatelet Therapy: A National Survey of Emergency Medicine Physicians

BACKGROUND

Treatment with aspirin plus clopidogrel, dual antiplatelet therapy (DAPT), within 24 hours of high-risk transient ischemic attack (TIA) or minor stroke symptoms to eligible patients is recommended by national guidelines. Whether or not this treatment has been adopted by emergency medicine (EM) physicians is uncertain.

METHODS

We conducted an online survey of EM physicians in the United States. The survey consisted of 13 multiple choice questions regarding physician characteristics, practice settings, and usual approach to TIA and minor stroke treatment. We report participant characteristics and use chi-squared tests to compare between groups.

RESULTS

We included 162 participants in the final study analysis. 103 participants (64%) were in practice for >5 years and 96 (59%) were at nonacademic centers; all were EM board-certified or board-eligible. Only 9 (6%) participants reported that they would start DAPT for minor stroke and 8 (5%) reported that they would start DAPT after high-risk TIA. Aspirin alone was the selected treatment by 81 (50%) participants for minor stroke patients who presented within 24 hours of symptom onset and were not candidates for thrombolysis. For minor stroke, 69 (43%) participants indicated that they would defer medical management to consultants or another team. Similarly, 75 (46%) of participants chose aspirin alone to treat high-risk TIA; 74 (46%) reported they would defer medical management after TIA to consultants or another team.

CONCLUSION

In a survey of EM physicians, we found that the reported rate of DAPT treatment for eligible patients with high-risk TIA and minor stroke was low.

Evaluation of microalbuminuria as a prognostic indicator after a TIA or minor stroke in an outpatient setting: the prognostic role of microalbuminuria in TIA evolution (ProMOTE) study

OBJECTIVE

Transient ischaemic attacks (TIA) and minor strokes are important risk factors for further vascular events. We explored the role of albumin creatinine ratio (ACR) in improving risk prediction after a first event.

SETTING

Rapid access stroke clinics in the UK.

PARTICIPANTS

2202 patients attending with TIA or minor stroke diagnosed by the attending stroke physician, able to provide a urine sample to evaluate ACR using a near-patient testing device.

PRIMARY AND SECONDARY OUTCOMES

Primary outcome was major adverse cardiac events (MACE: recurrent stroke, myocardial infarction or cardiovascular death) at 90 days. The key secondary outcome was to determine whether urinary ACR could contribute to a risk prediction tool for use in a clinic setting.

RESULTS

151 MACE occurred in 144 participants within 90 days. Participants with MACE had higher ACR than those without. A composite score awarding a point each for age >80 years, previous stroke/TIA and presence of microalbuminuria identified those at low risk and high risk. 90% of patients were at low risk (scoring 0 or 1). Their 90-day risk of MACE was 5.7%. Of the remaining 'high-risk' population (scoring 2 or 3) 12.4% experienced MACE over 90 days (p<0.001 compared with the low-risk population). The need for acute admission in the first 7 days was twofold elevated in the high-risk group compared with the low-risk group (3.23% vs 1.43%; p=0.05). These findings were validated in an independent historic sample.

CONCLUSION

A risk score comprising age, previous stroke/TIA and microalbuminuria predicts future MACE while identifying those at low risk of a recurrent event. This tool shows promise in the risk stratification of patients to avoid the admission of low-risk patients.

Drugs in secondary stroke prevention

After an ischaemic stroke or transient ischaemic attack, patients have a high risk of having another stroke. Secondary stroke prevention includes antiplatelet therapy, statins and antihypertensives

Aspirin, clopidogrel, or a combination of aspirin with dipyridamole are first-line options for secondary stroke prevention in the absence of atrial fibrillation

Dual antiplatelet therapy has a benefit in the first three weeks after stroke, but patients should change to a single antiplatelet drug after this time

Anticoagulants are indicated if the patient has atrial fibrillation. Avoid combinations of anticoagulants and antiplatelet drugs

Patients should be started on statins after an ischaemic stroke. High doses are recommended even if cholesterol concentrations are normal

Antihypertensive drugs are recommended for all patients with systolic blood pressures greater than 140/90 mmHg. ACE inhibitors, calcium channel blockers and diuretics are first-line options

Power of Hypoperfusion in Predicting Recurrent Transient Ischemic Attacks: Protocol of a Prospective Cohort Study

Background: Transient ischemic attack (TIA) has a high incidence of recurrent vascular events. Hypoperfusion is one of the factors that are closely correlated with 7-day recurrence of TIA. This study aimed to evaluate the power of hypoperfusion shown on magnetic resonance (MR) perfusion imaging in predicting the incidence of 7-day recurrence of ischemic events after TIA.

Methods/Design: REATTACK is a prospective multi-centered cohort study on the correlation between MR perfusion and TIA recurrence. Ninety patients aged ≥18 years with recent (<7 days after onset) clinical TIA will be continuously included. All the patients will undergo diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) assessments within 24 h after the onset of TIA. The subjects will then be divided into a PWI positive group and a PWI negative group according to the time-to-maximum of the residue function (T_max). PWI will be repeated after 7 days and in 3 months. The primary clinical outcome will be the recurrence of TIA within 7 days after the onset of TIA. Secondary outcomes will be the recurrence of TIA in 3 months and modified Rankin scale (mRS) score. A chi-square test will be performed to compare the difference in the incidence of recurrent TIA between the two groups, and rank sum test in the mRS score. Multivariate logistic regression will be simultaneously performed to analyze the risk factors for the recurrence of TIA.

Discussion: The results of this study will confirm whether abnormal T_max helps to identify the patients with TIA who have high risks of recurrent ischemic events. This would largely improve the prognosis of patients with TIA.

Trial Registration:www.chictr.org.cn, registration number: ChiCTR2000031863, registered on 12 April 2020.

Prospective validation of Canadian TIA Score and comparison with ABCD2 and ABCD2i for subsequent stroke risk after transient ischaemic attack: multicentre prospective cohort study

OBJECTIVE

To validate the previously derived Canadian TIA Score to stratify subsequent stroke risk in a new cohort of emergency department patients with transient ischaemic attack.

DESIGN

Prospective cohort study.

SETTING

13 Canadian emergency departments over five years.

PARTICIPANTS

7607 consecutively enrolled adult patients attending the emergency department with transient ischaemic attack or minor stroke.

MAIN OUTCOME MEASURES

The primary outcome was subsequent stroke or carotid endarterectomy/carotid artery stenting within seven days. The secondary outcome was subsequent stroke within seven days (with or without carotid endarterectomy/carotid artery stenting). Telephone follow-up used the validated Questionnaire for Verifying Stroke Free Status at seven and 90 days. All outcomes were adjudicated by panels of three stroke experts, blinded to the index emergency department visit.

RESULTS

Of the 7607 patients, 108 (1.4%) had a subsequent stroke within seven days, 83 (1.1%) had carotid endarterectomy/carotid artery stenting within seven days, and nine had both. The Canadian TIA Score stratified the risk of stroke, carotid endarterectomy/carotid artery stenting, or both within seven days as low (risk ≤0.5%; interval likelihood ratio 0.20, 95% confidence interval 0.09 to 0.44), medium (risk 2.3%; interval likelihood ratio 0.94, 0.85 to 1.04), and high (risk 5.9% interval likelihood ratio 2.56, 2.02 to 3.25) more accurately (area under the curve 0.70, 95% confidence interval 0.66 to 0.73) than did the ABCD2 (0.60, 0.55 to 0.64) or ABCD2i (0.64, 0.59 to 0.68). Results were similar for subsequent stroke regardless of carotid endarterectomy/carotid artery stenting within seven days.

CONCLUSION

The Canadian TIA Score stratifies patients' seven day risk for stroke, with or without carotid endarterectomy/carotid artery stenting, and is now ready for clinical use. Incorporating this validated risk estimate into management plans should improve early decision making at the index emergency visit regarding benefits of hospital admission, timing of investigations, and prioritisation of specialist referral.

Outcomes of Medicare beneficiaries hospitalised with transient ischaemic attack and stratification using the ABCD2 score

BACKGROUND

Long-term outcomes for Medicare beneficiaries hospitalised with transient ischaemic attack (TIA) and role of ABCD² score in identifying high-risk individuals are not studied.

METHODS

We identified 40 825 Medicare beneficiaries hospitalised from 2011 to 2014 for a TIA to a Get With The Guidelines (GWTG)-Stroke hospital and classified them using ABCD² score. Proportional hazards models were used to assess 1-year event rates of mortality and rehospitalisation (all-cause, ischaemic stroke, haemorrhagic stroke, myocardial infarction, and gastrointestinal and intracranial haemorrhage) for high-risk versus low-risk groups adjusted for patient and hospital characteristics.

RESULTS

Of the 40 825 patients, 35 118 (86%) were high risk (ABCD² ≥4) and 5707 (14%) were low risk (ABCD²=0-3). Overall rate of mortality during 1-year follow-up after hospital discharge for the index TIA was 11.7%, 44.3% were rehospitalised for any reason and 3.6% were readmitted due to stroke. Patients with ABCD² score ≥4 had higher mortality at 1 year than not (adjusted HR 1.18, 95% CI 1.07 to 1.30). Adjusted risks for ischaemic stroke, all-cause readmission and mortality/all-cause readmission at 1 year were also significantly higher for patients with ABCD² score ≥4 vs 0-3. In contrast, haemorrhagic stroke, myocardial infarction, gastrointestinal bleeding and intracranial haemorrhage risk were not significantly different by ABCD² score.

CONCLUSIONS

This study validates the use of ABCD² score for long-term risk assessment after TIA in patients aged 65 years and older. Attentive efforts for community-based follow-up care after TIA are needed for ongoing prevention in Medicare beneficiaries who were hospitalised for TIA.

Matrix Gla protein polymorphism rs1800801 associates with recurrence of ischemic stroke

The MGP single nucleotide polymorphism (SNP) rs1800801 has previously been associated with recurrent ischemic stroke in a Spanish cohort. Here, we tested for association of this SNP with ischemic stroke recurrence in a North American Caucasian cohort. Acute ischemic stroke patients admitted between 10/2009 and 12/2016 at three hospitals within a large healthcare system in the northeastern United States that were enrolled in a healthcare system-wide exome sequencing program were retrospectively reviewed. Patients with recurrent stroke within 1 year after index event were compared to those without recurrence. Of 9,348 suspected acute ischemic strokes admitted between 10/2009 and 12/2016, 1,727 (18.5%) enrolled in the exome-sequencing program. Among those, 1,068 patients had exome sequencing completed and were eligible for inclusion. Recurrent stroke within the first year of stroke was observed in 79 patients (7.4%). In multivariable analysis, stroke prior to the index stroke (OR 9.694, 95% CI 5.793-16.224, p ≤ 0.001), pro-coagulant status (OR = 3.563, 95% CI 1.504-8.443, p = 0.004) and the AA genotype of SNP rs1800801 (OR = 2.408, 95% CI 1.079-4.389, p = 0.004) were independently associated with recurrent stroke within the first year. The AA genotype of the MGP SNP rs1800801 is associated with recurrence within the first year after ischemic stroke in North American Caucasians. Study of stroke subtypes and additional populations will be required to determine if incorporation of allelic status at this SNP into current risk scores improves prediction of recurrent ischemic stroke.

Incidence and Predictors of Acute Ischemic Lesions on Brain Magnetic Resonance Imaging in Patients With a Clinical Diagnosis of Transient Ischemic Attack in China

Background: The associations between the clinical characteristics and diffusion-weighted imaging (DWI) positivity in patients with a clinical diagnosis of transient ischemic attack (TIA) are still poorly understood. The purpose of our study was to determine the incidence of TIA related acute infarction by DWI, and to determine the underlying predictors of DWI positivity in TIA patients.

Methods: Between Jan 2017 and Dec 2018, we retrospectively enrolled 430 patients with a clinical diagnosis of TIA who underwent DWI. Patients were divided into those with acute ischemic lesions (DWI positive group) and those without (DWI negative group). The clinical characteristics, laboratory data, and imaging parameters were compared between the two groups.

Results: A total of 430 time-based TIA patients (mean age, 61.4 ± 13.0) were enrolled in this study. About 126 (29.3%) of TIA patients had a DWI positive lesion in our series. Comparing TIA patients with positive DWI to those with negative DWI, acute lesions were more likely to be more male, have higher hyperlipidemia and a smoking history, more speech abnormalities and increased motor weakness; and higher systolic and diastolic blood pressure, homocysteine, fasting blood glucose, and the scores of ABCD2, ABCD3, ABCD3-I, and Dawson. Several independent predictors of DWI positivity were identified with logistic regression analysis: motor weakness (odds ratio 4.861, P = 0.021), speech abnormalities (odds ratio 4.029, P = 0.024), and ABCD3-I (odds ratio 13.141, P = 0.001). ABCD3-I showed the greatest area under the ROC curve, with a sensitivity of 85.7% and specificity of 72.4%.

Conclusion: In patients with a clinical diagnosis of TIA, 29.3% demonstrated acute DWI lesions on brain magnetic resonance imaging (MRI). They were associated with motor weakness, speech abnormalities and higher ABCD3-I score at admission.

Empirical evidence of the impact of study characteristics on the performance of prediction models: a meta-epidemiological study

OBJECTIVES

To empirically assess the relation between study characteristics and prognostic model performance in external validation studies of multivariable prognostic models.

DESIGN

Meta-epidemiological study.

DATA SOURCES AND STUDY SELECTION

On 16 October 2018, we searched electronic databases for systematic reviews of prognostic models. Reviews from non-overlapping clinical fields were selected if they reported common performance measures (either the concordance (c)-statistic or the ratio of observed over expected number of events (OE ratio)) from 10 or more validations of the same prognostic model.

DATA EXTRACTION AND ANALYSES

Study design features, population characteristics, methods of predictor and outcome assessment, and the aforementioned performance measures were extracted from the included external validation studies. Random effects meta-regression was used to quantify the association between the study characteristics and model performance.

RESULTS

We included 10 systematic reviews, describing a total of 224 external validations, of which 221 reported c-statistics and 124 OE ratios. Associations between study characteristics and model performance were heterogeneous across systematic reviews. C-statistics were most associated with variation in population characteristics, outcome definitions and measurement and predictor substitution. For example, validations with eligibility criteria comparable to the development study were associated with higher c-statistics compared with narrower criteria (difference in logit c-statistic 0.21(95% CI 0.07 to 0.35), similar to an increase from 0.70 to 0.74). Using a case-control design was associated with higher OE ratios, compared with using data from a cohort (difference in log OE ratio 0.97(95% CI 0.38 to 1.55), similar to an increase in OE ratio from 1.00 to 2.63).

CONCLUSIONS

Variation in performance of prognostic models across studies is mainly associated with variation in case-mix, study designs, outcome definitions and measurement methods and predictor substitution. Researchers developing and validating prognostic models should realise the potential influence of these study characteristics on the predictive performance of prognostic models.

Imaging Diagnosis of Transient Ischemic Attack in Clinic and Traditional Chinese Medicine

Neuroimaging plays a pivotal role in Transient Ischemic Attack (TIA). Generally, clinicians focus on the specific changes in morphology and function, but the diagnosis of TIA often depends on imaging evidence. Whereas Traditional Chinese Medicine (TCM) is concerned with the performance of clinical symptoms, they began to use imaging methods to diagnose TIA. CT and MRI are the recommended modality to diagnose TIA and image ischemic lesions. In addition, Transcranial Doppler sonography (TCD) and Digital Subtraction Angiography (DSA) are two acceptable alternatives for diagnosing TIA patients. This article elaborates the update of imaging modalities in clinic and the development of imaging modalities in TCM. Besides, multiple joint imaging technologies also will be evaluated whether enhanced diagnostic yields availably.

Stroke risk after transient ischemic attack in a Norwegian prospective cohort

BACKGROUND

Transient ischemic attack (TIA) is a risk factor of stroke. Modern treatment regimens and changing risk factors in the population justify new estimates of stroke risk after TIA, and evaluation of the recommended ABCD² stroke risk score.

METHODS

From October, 2012, to July, 2014, we performed a prospective, multicenter study in Central Norway, enrolling patients with a TIA within the previous 2 weeks. Our aim was to assess stroke risk at 1 week, 3 months and 1 year after TIA, and to determine the predictive value of the dichotomized ABCD² score (0-3 vs 4-7) at each time point. We used data obtained by telephone follow-up and registry data from the Norwegian Stroke Register.

RESULTS

Five hundred and seventy-seven patients with TIA were enrolled of which 85% were examined by a stroke specialist within 24 h after symptom onset. The cumulative incidence of stroke within 1 week, 3 months and 1 year of TIA was 0.9% (95% CI, 0.37-2.0), 3.3% (95% CI, 2.1-5.1) and 5.4% (95% CI, 3.9-7.6), respectively. The accuracy of the ABCD² score provided by c-statistics at 7 days, 3 months and 1 year was 0.62 (95% CI, 0.39-0.85), 0.62 (95% CI, 0.51-0.74) and 0.64 (95% CI, 0.54-0.75), respectively.

CONCLUSIONS

We found a lower stroke risk after TIA than reported in earlier studies. The ABCD² score did not reliably discriminate between low and high risk patients, suggesting that it may be less useful in populations with a low risk of stroke after TIA.

TRIAL REGISTRATION

Unique identifier: NCT02038725 (retrospectively registered, January 16, 2014).

Predicting Long-Term Cardiovascular Events after Transient Ischemic Attacks: Carotid Artery Intima-Media Thickness or ABCD2 Score or Both?

Background

Patients who experienced transient ischemic attack (TIA) are at high-risk for cardiovascular events. This study aims to evaluate diagnostic value of carotid artery intima-media thickness (CIMT) and ABCD2 score for predicting cardiovascular events in long-term follow-up after TIA. We prospectively included sixty patients with TIA who admitted to hospital from March 2016 to August 2016.

Methods

Duplex ultrasonography of internal carotid arteries was performed. ABCD2 scores were evaluated for each patient. At a median follow-up of 20 months, patients were asked about new cardiovascular events. We used IBM SPSS software version 22.0 with Chi-squared, t-test, ANOVA, receiver operating characteristic, and area under the curve (AUC) analysis for our work.

Results

Sensitivity and negative predictive value of the combined score (ABCD2+CIMT) was the highest (96.3% and 90.9%, respectively), and the specificity and positive predictive value of the CIMT were the highest (57.5% and 63.1%, respectively) to predict cardiovascular events in long-term.

Conclusion

Compared to ABCD2 score, CIMT proved to be more accurate to predict cardiovascular events in long-term follow-ups (AUC = 0.736 vs. AUC = 0.640). However, adding CIMT value to ABCD2 score was even better (AUC = 0.750). Therefore, CIMT measurement in the ABCD2 score after TIA enables prediction of long-term cardiovascular events.

Recent advances in the management of transient ischemic attacks

Significant advances in our understanding of transient ischemic attack (TIA) have taken place since it was first recognized as a major risk factor for stroke during the late 1950's. Recently, numerous studies have consistently shown that patients who have experienced a TIA constitute a heterogeneous population, with multiple causative factors as well as an average 5–10% risk of suffering a stroke during the 30 days that follow the index event. These two attributes have driven the most important changes in the management of TIA patients over the last decade, with particular attention paid to effective stroke risk stratification, efficient and comprehensive diagnostic assessment, and a sound therapeutic approach, destined to reduce the risk of subsequent ischemic stroke. This review is an outline of these changes, including a discussion of their advantages and disadvantages, and references to how new trends are likely to influence the future care of these patients.

Variation in Organization of Transient Ischemic Attack Care in The Netherlands. A Nationwide Survey Study

BACKGROUND

Previous research has shown the importance of urgent initiation of antiplatelet therapy after transient ischemic attack (TIA) to reduce the risk of stroke. Many hospitals in the Netherlands have therefore implemented rapid pathways for assessment of patients with TIA. Dutch stroke guidelines lack clear directives for organization of TIA assessment and thus allow for variation. The aim of this study was to investigate variation in organization of TIA assessment in Dutch hospitals.

METHODS

One neurologist per hospital (of 88 Dutch hospitals) with special interest in stroke was invited to participate in a web-based survey addressing the organization, content, and timing of TIA assessment.

RESULTS

Seventy (80%) neurologists completed the survey, all of whom reported performing TIA assessment in their hospital. There was considerable variation in the method of application and the location of assessment. In 10% of the hospitals, patients with TIA are always admitted to the ward. The content of diagnostics is fairly similar, but hospitals vary in the extent of cardiological workup. Almost all hospitals aim for a swift start of assessment as directed by guidelines, but access time differs. Eighty-six percent of respondents reported that antiplatelet therapy is usually initiated before assessment, based on history.

CONCLUSIONS

This study showed variation in organization of TIA assessment in Dutch hospitals, especially regarding location within the hospital, time to assessment after announcement, and cardiological workup. Further research is needed to investigate implications of this variation for quality of care.

Pathways for Neuroimaging of Childhood Stroke

BACKGROUND

The purpose of this article is to aid practitioners in choosing appropriate neuroimaging for children who present with symptoms that could be caused by stroke.

METHODS

The Writing Group members participated in one or more pediatric stroke neuroimaging symposiums hosted by the Stroke Imaging Laboratory for Children housed at the Hospital for Sick Children in Toronto, Ontario, Canada. Through collaboration, literature review, and discussion among child neurologists with expertise diagnosing and treating childhood stroke and pediatric neuroradiologists and neuroradiologists with expertise in pediatric neurovascular disease, suggested imaging protocols are presented for children with suspected stroke syndromes including arterial ischemic stroke, cerebral sinovenous thrombosis, and hemorrhagic stroke.

RESULTS

This article presents information about the epidemiology and classification of childhood stroke with definitions based on the National Institutes of Health Common Data Elements. The role of imaging for the diagnosis of childhood stroke is examined in depth, with separate sections for arterial ischemic stroke, cerebral sinovenous thrombosis, and hemorrhagic stroke. Abbreviated neuroimaging protocols for rapid diagnosis are discussed. The Writing Group provides suggestions for optimal neuroimaging investigation of various stroke types in the acute setting and suggestions for follow-up neuroimaging. Advanced sequences such as diffusion tensor imaging, perfusion imaging, and vessel wall imaging are also discussed.

CONCLUSIONS

This article provides protocols for the imaging of children who present with suspected stroke.

Validation and comparison of imaging-based scores for prediction of early stroke risk after transient ischaemic attack: a pooled analysis of individual-patient data from cohort studies

BACKGROUND

Identification of patients at highest risk of early stroke after transient ischaemic attack has been improved with imaging based scores. We aimed to compare the validity and prognostic utility of imaging-based stroke risk scores in patients after transient ischaemic attack.

METHODS

We did a pooled analysis of published and unpublished individual-patient data from 16 cohort studies of transient ischaemic attack done in Asia, Europe, and the USA, with early brain and vascular imaging and follow up. All patients were assessed by stroke specialists in hospital settings as inpatients, in emergency departments, or in transient ischaemic attack clinics. Inclusion criteria were stroke-specialist confirmed transient ischaemic attack, age of 18 years or older, and MRI done within 7 days of index transient ischaemic attack and before stroke recurrence. Multivariable logistic regression was done to analyse the predictive utility of abnormal diffusion-weighted MRI, carotid stenosis, and transient ischaemic attack within 1 week of index transient ischaemic attack (dual transient ischaemic attack) after adjusting for ABCD2 score. We compared the prognostic utility of the ABCD2, ABCD2-I, and ABCD3-I scores using discrimination, calibration, and risk reclassification.

FINDINGS

In 2176 patients from 16 cohort studies done between 2005 and 2015, after adjusting for ABCD2 score, positive diffusion-weighted imaging (odds ratio [OR] 3·8, 95% CI 2·1-7·0), dual transient ischaemic attack (OR 3·3, 95% CI 1·8-5·8), and ipsilateral carotid stenosis (OR 4·7, 95% CI 2·6-8·6) were associated with 7 day stroke after index transient ischaemic attack (p<0·001 for all). 7 day stroke risk increased with increasing ABCD2-I and ABCD3-I scores (both p<0·001). Discrimination to identify early stroke risk was improved for ABCD2-I versus ABCD2 (2 day c statistic 0·74 vs 0·64; p=0·006). However, discrimination was further improved by ABCD3-I compared with ABCD2 (2 day c statistic 0·84 vs 0·64; p<0·001) and ABCD2-I (c statistic 0·84 vs 0·74; p<0·001). Early stroke risk reclassification was improved by ABCD3-I compared with ABCD2-I score (clinical net reclassification improvement 33% at 2 days).

INTERPRETATION

Although ABCD2-I and ABCD3-I showed validity, the ABCD3-I score reliably identified highest-risk patients at highest risk of a stroke after transient ischaemic attack with improved risk prediction compared with ABCD2-I. Transient ischaemic attack management guided by ABCD3-I with immediate stroke-specialist assessment, urgent MRI, and vascular imaging should now be considered, with monitoring of safety and cost-effectiveness.

FUNDING

Health Research Board of Ireland, Irish Heart Foundation, Irish Health Service Executive, Irish National Lottery, National Medical Research Council of Singapore, Swiss National Science Foundation, Bangerter-Rhyner Foundation, Swiss National Science Foundation, Swisslife Jubiläumsstiftung for Medical Research, Swiss Neurological Society, Fondazione Dr Ettore Balli (Switzerland), Clinical Trial Unit of University of Bern, South Korea's Ministry for Health, Welfare, and Family Affairs, UK Wellcome Trust, Wolfson Foundation, UK Stroke Association, British Heart Foundation, Dunhill Medical Trust, National Institute of Health Research (NIHR), Medical Research Council, and the NIHR Oxford Biomedical Research Centre.

The Value of ABCD2F Scoring System (ABCD2 Combined with Atrial Fibrillation) to Predict 90-Day Recurrent Brain Stroke

Background. The ABCD2 score is now identified as a useful clinical prediction rule to determine the risk for stroke in the days following brain ischemic attacks. Aim. The present study aimed to introduce a new scoring system named "ABCD2F" and compare its value with the previous ABCD2 system to predict recurrent ischemic stroke within 90 days of the initial cerebrovascular accident (CVA). Methods. 138 consecutive patients with the final diagnosis of ischemic CVA or TIAs who referred to emergency ward of Rasoul-e-Akram general hospital in Tehran from September 2012 to December 2013 were eligible. By adding a new score in the presence of atrial fibrillation to ABCD2 system, the new scoring system as ABCD2F was introduced and the risk stratification was done again on this new system. Results. The area under the curve for ABCD2 was 0.434 and for ABCD2F it was 0.452 indicating low value of both systems for assessing recurrence of stroke within 90 days of primary event. Multivariable logistic regression analysis showed that none of the baseline factors could predict 90-day recurrent stroke. Conclusion. ABCD2 and/or atrial fibrillation are not good scoring candidates for assessing the risk of recurrent stroke within first 90 days.

A pilot study evaluating the use of ABCD2 score in pre-hospital assessment of patients with suspected transient ischaemic attack: experience and lessons learned

BACKGROUND

Suspected transient ischaemic attack (TIA) is a common presentation to emergency medical services (EMS) in the United Kingdom (UK). Several EMS systems have adopted the ABCD2 score to aid pre-hospital risk stratification and decision-making on patient disposition, such as direct referral to an Emergency Department or specialist TIA clinic. However, the ABCD2 score, developed for hospital use, has not been validated for use in the pre-hospital context of EMS care.

METHODS

We conducted a pilot study to assess eligibility criteria, recruitment rates, protocol compliance, consent and follow-up procedures to inform the development of a definitive study to validate the ABCD2 tool in pre-hospital evaluation of patients with suspected TIA.

RESULTS

From 1st May-1st September 2013, nine patients with an EMS suspected diagnosis of TIA had the TIA diagnosis later confirmed by a specialist from five participating sites. This recruitment rate is comparable to stroke trials in the EMS setting. Bureaucratic obstacles and duplication of approval processes across participating sites took 13 months to resolve before recruitment commenced. Due to the initial difficulty in recruitment, a substantial amendment was approved to modify inclusion criteria, allowing patients with atrial fibrillation and/or taking anticoagulant therapy to participate in the study.

CONCLUSIONS

It is possible to identify, recruit and follow up patients with suspected TIA in the EMS setting. Training large numbers of EMS staff is required as exposure to TIA patients is infrequent. Significant insight was gained into the complexity of NHS research governance mechanisms in the UK. This knowledge will facilitate the planning of a future adequately powered study to validate the ABCD2 tool in a pre-hospital setting.

Quality of Care and Ischemic Stroke Risk After Hospitalization for Transient Ischemic Attack: Findings From Get With The Guidelines-Stroke

BACKGROUND

Patients with transient ischemic attack (TIA) are at increased risk for ischemic stroke. We derived a prediction rule for 1-year ischemic stroke risk post-TIA, examining estimated risk, receipt of inpatient quality of care measures for TIA, and the presence or absence of stroke at 1 year post discharge.

METHODS AND RESULTS

We linked 67 892 TIA Get With The Guidelines-Stroke patients >65 years (2003-2008) to Medicare inpatient claims to obtain longitudinal outcomes. Using Cox proportional hazards modeling in a split sample, we identified baseline demographics and clinical characteristics associated with ischemic stroke admission during the year post-TIA, and developed a Get With The Guidelines Ischemic Stroke after TIA Risk Score; performance was examined in the validation sample. Quality of care was estimated by a global defect-free care measure, and individual performance measures within estimated risk score quintiles. The overall hospital admission rate for ischemic stroke during the year post-TIA was 5.7%. Patients with ischemic stroke were more likely to be older, black, and have higher rates of smoking, previous stroke, diabetes mellitus, previous myocardial infarction, heart failure, and atrial fibrillation. The Risk Score showed moderate discriminative performance (c-statistic=0.606); highest quintile patients were less likely to receive statins, smoking cessation counseling, and defect-free care. Although not associated with 1-year ischemic stroke, DCF was associated with a significantly lower risk of all-cause mortality.

CONCLUSIONS

TIA patients with high estimated ischemic stroke risk are less likely to receive defect-free care than low-risk patients. Standardized risk assessment and delivery of optimal inpatient care are needed to reduce this risk-treatment mismatch.

Microalbuminuria could improve risk stratification in patients with TIA and minor stroke

Objective

Transient ischemic attacks (TIA) and minor strokes are important risk factors for recurrent strokes. Current stroke risk prediction scores such as ABCD2, although widely used, lack optimal sensitivity and specificity. Elevated urinary albumin excretion predicts cardiovascular disease, stroke, and mortality. We explored the role of microalbuminuria (using albumin creatinine ratio (ACR)) in predicting recurrence risk in patients with TIA and minor stroke.

Methods

Urinary ACR was measured on a spot sample in 150 patients attending a daily stroke clinic with TIA or minor stroke. Patients were followed up at day 7, 30, and 90 to determine recurrent stroke, cardiovascular events, or death. Eligible patients had a carotid ultrasound Doppler investigation. High‐risk patients were defined as those who had an event within 90 days or had >50% internal carotid artery (ICA) stenosis.

Results

Fourteen (9.8%) recurrent events were reported by day 90 including two deaths. Fifteen patients had severe ICA stenosis. In total, 26 patients were identified as high risk. These patients had a higher frequency of previous stroke or hypercholesterolemia compared to low‐risk patients (P = 0.04). ACR was higher in high‐risk patients (3.4 [95% CI 2.2–5.2] vs. 1.7 [1.5–2.1] mg/mmol, P = 0.004), independent of age, sex, blood pressure, diabetes, and previous stroke. An ACR greater than 1.5 mg/mmol predicted high‐risk patients (Cox proportional hazard ratio 3.5 (95% CI 1.3–9.5, P = 0.01).

Interpretation

After TIA or minor stroke, a higher ACR predicted recurrent events and significant ICA stenosis. Incorporation of urinary ACR from a spot sample in the acute setting could improve risk stratification in patients with TIA and minor stroke.

One-Year Risk of Stroke after Transient Ischemic Attack or Minor Stroke

BACKGROUND

Previous studies conducted between 1997 and 2003 estimated that the risk of stroke or an acute coronary syndrome was 12 to 20% during the first 3 months after a transient ischemic attack (TIA) or minor stroke. The TIAregistry.org project was designed to describe the contemporary profile, etiologic factors, and outcomes in patients with a TIA or minor ischemic stroke who receive care in health systems that now offer urgent evaluation by stroke specialists.

METHODS

We recruited patients who had had a TIA or minor stroke within the previous 7 days. Sites were selected if they had systems dedicated to urgent evaluation of patients with TIA. We estimated the 1-year risk of stroke and of the composite outcome of stroke, an acute coronary syndrome, or death from cardiovascular causes. We also examined the association of the ABCD(2) score for the risk of stroke (range, 0 [lowest risk] to 7 [highest risk]), findings on brain imaging, and cause of TIA or minor stroke with the risk of recurrent stroke over a period of 1 year.

RESULTS

From 2009 through 2011, we enrolled 4789 patients at 61 sites in 21 countries. A total of 78.4% of the patients were evaluated by stroke specialists within 24 hours after symptom onset. A total of 33.4% of the patients had an acute brain infarction, 23.2% had at least one extracranial or intracranial stenosis of 50% or more, and 10.4% had atrial fibrillation. The Kaplan-Meier estimate of the 1-year event rate of the composite cardiovascular outcome was 6.2% (95% confidence interval, 5.5 to 7.0). Kaplan-Meier estimates of the stroke rate at days 2, 7, 30, 90, and 365 were 1.5%, 2.1%, 2.8%, 3.7%, and 5.1%, respectively. In multivariable analyses, multiple infarctions on brain imaging, large-artery atherosclerosis, and an ABCD(2) score of 6 or 7 were each associated with more than a doubling of the risk of stroke.

CONCLUSIONS

We observed a lower risk of cardiovascular events after TIA than previously reported. The ABCD(2) score, findings on brain imaging, and status with respect to large-artery atherosclerosis helped stratify the risk of recurrent stroke within 1 year after a TIA or minor stroke. (Funded by Sanofi and Bristol-Myers Squibb.).

Validation of ABCD2 scores ascertained by referring clinicians: a retrospective transient ischaemic attack clinic cohort study

INTRODUCTION

Transient ischaemic attack (TIA) services routinely use ABCD2 scores ascertained by referring clinicians to triage patients. Most ABCD2 validation studies have used ABCD2 scores calculated by stroke-specialist investigators and not referring clinicians. This study aimed to assess the usefulness of referring clinicians' ABCD2 scores in predicting strokes.

METHODS

A retrospective study of a TIA clinic cohort from Gloucester, UK, followed up for 4 years from 2010 to 2012. ABCD2 scores were dichotomised to high risk-ABCD2≥4 and low risk-ABCD2<4. Outcomes of interest were subsequent stroke and stroke or TIA. Survival analysis was used determine the cumulative probability of these outcomes and to identify if ABCD2 risk category was associated with stroke.

RESULTS

Of 1067 (284 high risk, 783 low risk) patients, 49.6% were classified by the clinic stroke physicians as TIA/minor stroke and 50.4% as mimics. Follow-up was for a median of 34.9 (IQR 27.7-41.6) months with 56 strokes and 106 strokes/TIA. The number of strokes by 7 days, 90 days and 48 months, respectively, were: high risk 0, 2 and 20 and low risk 2, 6 and 36 (p=0.21). Unadjusted HR for subsequent stroke was 1.41 (95% CI 0.82 to 2.46) in the high-risk group compared with the low-risk group and HR adjusted for the diagnosis of TIA/stroke was 1.2 (95% CI 0.69 to 2.08).

CONCLUSIONS

ABCD2 scores recorded by referring clinicians did not identify patients at high risk of subsequent stroke, suggesting that the score should not be used for TIA clinic triage.

Implementation of a Community-Based Triage for Patients with Suspected Transient Ischemic Attack or Minor Stroke Study: A Prospective Multicenter Observational Study

BACKGROUND

Japan has the highest number of magnetic resonance imaging units in the world, and citizens can freely choose medical care at any hospital or clinic. We aimed to investigate the triage of patients with suspected transient ischemic attack (TIA) or minor stroke in this unique Japanese healthcare system.

METHODS

In this cohort study, patients with suspected TIA or minor stroke (National Institutes of Health Stroke Scale score <4) within 7 days after onset were prospectively enrolled and followed for 1 year. The high-risk group was defined as having at least one of the following 5 items at the initial visit: (1) atrial fibrillation, (2) carotid stenosis, (3) crescendo TIA, (4) definite focal brain symptoms, or (5) ABCD2 score of 4 or higher. After the initial assessment, the patients were diagnosed as having acute ischemic cerebrovascular syndrome (AICS) or stroke mimic. AICS was classified into 3 categories including definite, probable, and possible AICS, based on evidence of neurological deficits and brain infarction on the imaging study.

RESULTS

A total of 353 patients were enrolled and 89.8% of the patients were examined by diffusion-weighted imaging at the initial visit. Kaplan-Meier analyses demonstrated a statistically significant difference in subsequent stroke risk when the patients were triaged by the ABCD2 score (P = .031), 5-item high-risk categorization (P = .032), or AICS classification (P = .001).

CONCLUSIONS

This study demonstrates that hospitals and clinics with imaging facilities play a major role in triage and that the ABCD2 score, 5-item high-risk categorization, and AICS classification are useful as triage tools for patients with suspected TIA or minor stroke.

Design Characteristics Influence Performance of Clinical Prediction Rules in Validation: A Meta-Epidemiological Study

BACKGROUND

Many new clinical prediction rules are derived and validated. But the design and reporting quality of clinical prediction research has been less than optimal. We aimed to assess whether design characteristics of validation studies were associated with the overestimation of clinical prediction rules' performance. We also aimed to evaluate whether validation studies clearly reported important methodological characteristics.

METHODS

Electronic databases were searched for systematic reviews of clinical prediction rule studies published between 2006 and 2010. Data were extracted from the eligible validation studies included in the systematic reviews. A meta-analytic meta-epidemiological approach was used to assess the influence of design characteristics on predictive performance. From each validation study, it was assessed whether 7 design and 7 reporting characteristics were properly described.

RESULTS

A total of 287 validation studies of clinical prediction rule were collected from 15 systematic reviews (31 meta-analyses). Validation studies using case-control design produced a summary diagnostic odds ratio (DOR) 2.2 times (95% CI: 1.2-4.3) larger than validation studies using cohort design and unclear design. When differential verification was used, the summary DOR was overestimated by twofold (95% CI: 1.2 -3.1) compared to complete, partial and unclear verification. The summary RDOR of validation studies with inadequate sample size was 1.9 (95% CI: 1.2 -3.1) compared to studies with adequate sample size. Study site, reliability, and clinical prediction rule was adequately described in 10.1%, 9.4%, and 7.0% of validation studies respectively.

CONCLUSION

Validation studies with design shortcomings may overestimate the performance of clinical prediction rules. The quality of reporting among studies validating clinical prediction rules needs to be improved.

At risk or not at risk? A meta-analysis of the prognostic accuracy of psychometric interviews for psychosis prediction

An accurate detection of individuals at clinical high risk (CHR) for psychosis is a prerequisite for effective preventive interventions. Several psychometric interviews are available, but their prognostic accuracy is unknown. We conducted a prognostic accuracy meta-analysis of psychometric interviews used to examine referrals to high risk services. The index test was an established CHR psychometric instrument used to identify subjects with and without CHR (CHR+ and CHR-). The reference index was psychosis onset over time in both CHR+ and CHR- subjects. Data were analyzed with MIDAS (STATA13). Area under the curve (AUC), summary receiver operating characteristic curves, quality assessment, likelihood ratios, Fagan's nomogram and probability modified plots were computed. Eleven independent studies were included, with a total of 2,519 help-seeking, predominately adult subjects (CHR+: N=1,359; CHR-: N=1,160) referred to high risk services. The mean follow-up duration was 38 months. The AUC was excellent (0.90; 95% CI: 0.87-0.93), and comparable to other tests in preventive medicine, suggesting clinical utility in subjects referred to high risk services. Meta-regression analyses revealed an effect for exposure to antipsychotics and no effects for type of instrument, age, gender, follow-up time, sample size, quality assessment, proportion of CHR+ subjects in the total sample. Fagan's nomogram indicated a low positive predictive value (5.74%) in the general non-help-seeking population. Albeit the clear need to further improve prediction of psychosis, these findings support the use of psychometric prognostic interviews for CHR as clinical tools for an indicated prevention in subjects seeking help at high risk services worldwide.

ABCD2 score and secondary stroke prevention: meta-analysis and effect per 1,000 patients triaged

OBJECTIVE

Patients with TIA have high risk of recurrent stroke and require rapid assessment and treatment. The ABCD2 clinical risk prediction score is recommended for patient triage by stroke risk, but its ability to stratify by known risk factors and effect on clinic workload are unknown.

METHODS

We performed a systematic review and meta-analysis of all studies published between January 2005 and September 2014 that reported proportions of true TIA/minor stroke or mimics, risk factors, and recurrent stroke rates, dichotomized to ABCD2 score </≥4. We calculated the effect per 1,000 patients triaged on stroke prevention services.

RESULTS

Twenty-nine studies, 13,766 TIA patients (range 69-1,679), were relevant: 48% calculated the ABCD2 score retrospectively; few reported on the ABCD2 score's ability to identify TIA mimics or use by nonspecialists. Meta-analysis showed that ABCD2 ≥4 was sensitive (86.7%, 95% confidence interval [CI] 81.4%-90.7%) but not specific (35.4%, 95% CI 33.3%-37.6%) for recurrent stroke within 7 days. Additionally, 20% of patients with ABCD2 <4 had >50% carotid stenosis or atrial fibrillation (AF); 35%-41% of TIA mimics, and 66% of true TIAs, had ABCD2 score ≥4. Among 1,000 patients attending stroke prevention services, including the 45% with mimics, 52% of patients would have an ABCD2 score ≥4.

CONCLUSION

The ABCD2 score does not reliably discriminate those at low and high risk of early recurrent stroke, identify patients with carotid stenosis or AF needing urgent intervention, or streamline clinic workload. Stroke prevention services need adequate capacity for prompt specialist clinical assessment of all suspected TIA patients for correct patient management.

Evaluation of Cranial and Cervical Arteries and Brain Tissue in Transient Ischemic Attack Patients with Magnetic Resonance Angiography and Diffusion-Weighted Imaging

Background

Magnetic resonance angiography (MRA) and diffusion-weighted imaging (DWI) have been widely used in the prediction of ischemic stroke; however, the differences of the 2 methods in detection the artery lesion differences between transient ischemic attack (TIA) and infarction patients have been long neglected. We performed the present study to investigate the differences between vessel characteristics detected by MRA and DWI in acute stroke and TIA patients.

Material/Methods

We classified 110 subjects into 2 groups and all the patients underwent both MRA and DWI. The degree of stenosis of cranial and cervical arteries, the distribution of the stenosis, the development and changes of the vessels, and the DWI scanning results of the brain tissue were all analyzed.

Results

We detected a significant difference in the number and the degree of stenosis of cranial and cervical arteries among the 3 groups (P=0.006). Compared with health controls, patients with TIA and cerebral infraction had much more severe stenosis and occlusive arteries (P<0.05). However, no significant difference was detected between TIA and cerebral infraction patients (P=0.148). Moreover, a higher rate of unilateral vertebral artery dysplasia was found in the vertebrobasilar TIA patients. Higher lesion signals were also observed by DWI in TIA patients of internal carotid artery system (4/8, 50%).

Conclusions

Vessel characteristics were not significantly different between TIA and infarction patients. Unilateral vertebral artery hypoplasia was a predisposing factor for vertebrobasilar TIA and ischemic focus in DWI detection was always caused by severe artery lesions.

A simplified approach to the pooled analysis of calibration of clinical prediction rules for systematic reviews of validation studies

Objective

Estimating calibration performance of clinical prediction rules (CPRs) in systematic reviews of validation studies is not possible when predicted values are neither published nor accessible or sufficient or no individual participant or patient data are available. Our aims were to describe a simplified approach for outcomes prediction and calibration assessment and evaluate its functionality and validity.

Study design and methods:

Methodological study of systematic reviews of validation studies of CPRs: a) ABCD² rule for prediction of 7 day stroke; and b) CRB-65 rule for prediction of 30 day mortality. Predicted outcomes in a sample validation study were computed by CPR distribution patterns (“derivation model”). As confirmation, a logistic regression model (with derivation study coefficients) was applied to CPR-based dummy variables in the validation study. Meta-analysis of validation studies provided pooled estimates of “predicted:observed” risk ratios (RRs), 95% confidence intervals (CIs), and indexes of heterogeneity (I²) on forest plots (fixed and random effects models), with and without adjustment of intercepts. The above approach was also applied to the CRB-65 rule.

Results

Our simplified method, applied to ABCD² rule in three risk strata (low, 0–3; intermediate, 4–5; high, 6–7 points), indicated that predictions are identical to those computed by univariate, CPR-based logistic regression model. Discrimination was good (c-statistics =0.61–0.82), however, calibration in some studies was low. In such cases with miscalibration, the under-prediction (RRs =0.73–0.91, 95% CIs 0.41–1.48) could be further corrected by intercept adjustment to account for incidence differences. An improvement of both heterogeneities and P-values (Hosmer-Lemeshow goodness-of-fit test) was observed. Better calibration and improved pooled RRs (0.90–1.06), with narrower 95% CIs (0.57–1.41) were achieved.

Conclusion

Our results have an immediate clinical implication in situations when predicted outcomes in CPR validation studies are lacking or deficient by describing how such predictions can be obtained by everyone using the derivation study alone, without any need for highly specialized knowledge or sophisticated statistics.

An assessment of the cost-effectiveness of magnetic resonance, including diffusion-weighted imaging, in patients with transient ischaemic attack and minor stroke: a systematic review, meta-analysis and economic evaluation

BACKGROUND

Patients with transient ischaemic attack (TIA) or minor stroke need rapid treatment of risk factors to prevent recurrent stroke. ABCD2 score or magnetic resonance diffusion-weighted brain imaging (MR DWI) may help assessment and treatment.

OBJECTIVES

Is MR with DWI cost-effective in stroke prevention compared with computed tomography (CT) brain scanning in all patients, in specific subgroups or as 'one-stop' brain-carotid imaging? What is the current UK availability of services for stroke prevention?

DATA SOURCES

Published literature; stroke registries, audit and randomised clinical trials; national databases; survey of UK clinical and imaging services for stroke; expert opinion.

REVIEW METHODS

Systematic reviews and meta-analyses of published/unpublished data. Decision-analytic model of stroke prevention including on a 20-year time horizon including nine representative imaging scenarios.

RESULTS

The pooled recurrent stroke rate after TIA (53 studies, 30,558 patients) is 5.2% [95% confidence interval (CI) 3.9% to 5.9%] by 7 days, and 6.7% (5.2% to 8.7%) at 90 days. ABCD2 score does not identify patients with key stroke causes or identify mimics: 66% of specialist-diagnosed true TIAs and 35-41% of mimics had an ABCD2 score of ≥ 4; 20% of true TIAs with ABCD2 score of < 4 had key risk factors. MR DWI (45 studies, 9078 patients) showed an acute ischaemic lesion in 34.3% (95% CI 30.5% to 38.4%) of TIA, 69% of minor stroke patients, i.e. two-thirds of TIA patients are DWI negative. TIA mimics (16 studies, 14,542 patients) make up 40-45% of patients attending clinics. UK survey (45% response) showed most secondary prevention started prior to clinic, 85% of primary brain imaging was same-day CT; 51-54% of patients had MR, mostly additional to CT, on average 1 week later; 55% omitted blood-sensitive MR sequences. Compared with 'CT scan all patients' MR was more expensive and no more cost-effective, except for patients presenting at > 1 week after symptoms to diagnose haemorrhage; strategies that triaged patients with low ABCD2 scores for slow investigation or treated DWI-negative patients as non-TIA/minor stroke prevented fewer strokes and increased costs. 'One-stop' CT/MR angiographic-plus-brain imaging was not cost-effective.

LIMITATIONS

Data on sensitivity/specificity of MR in TIA/minor stroke, stroke costs, prognosis of TIA mimics and accuracy of ABCD2 score by non-specialists are sparse or absent; all analysis had substantial heterogeneity.

CONCLUSIONS

Magnetic resonance with DWI is not cost-effective for secondary stroke prevention. MR was most helpful in patients presenting at > 1 week after symptoms if blood-sensitive sequences were used. ABCD2 score is unlikely to facilitate patient triage by non-stroke specialists. Rapid specialist assessment, CT brain scanning and identification of serious underlying stroke causes is the most cost-effective stroke prevention strategy.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Prediction of recurrent stroke with ABCD2 and ABCD3 scores in patients with symptomatic 50-99% carotid stenosis

BACKGROUND

Although it is preferable that all patients with a recent Transient Ischemic Attack (TIA) undergo acute carotid imaging, there are centers with limited access to such acute examinations. It is controversial whether ABCD2 or ABCD3 scores can be used to triage patients to acute or delayed carotid imaging. It would be acceptable that some patients with a symptomatic carotid stenosis are detected with a slight delay as long as those who will suffer an early recurrent stroke are detected within 24 hours. The aim of this study is to analyze the ability of ABCD2 and ABCD3 scores to predict ipsilateral ischemic stroke among patients with symptomatic 50-99% carotid stenosis.

METHODS

In this secondary analysis of the ANSYSCAP-study, we included 230 consecutive patients with symptomatic 50-99% carotid stenosis. We analyzed the risk of recurrent ipsilateral ischemic stroke before carotid endarterectomy based on each parameter of the ABCD2 and ABCD3 scores separately, and for total ABCD2 and ABCD3 scores. We used Kaplan-Meier analysis.

RESULTS

None of the parameters in the ABCD2 or ABCD3 scores could alone predict all 12 of the ipsilateral ischemic strokes that occurred within 2 days of the presenting event, but clinical presentation tended to be a statistically significant risk factor for recurrent ipsilateral ischemic stroke (p = 0.06, log rank test). An ABCD2 score ≥2 and an ABCD3 score ≥4 could predict all 12 of these strokes as well as all 25 ipsilateral ischemic strokes that occurred within 14 days. To use ABCD3 score seems preferable over the ABCD2 score because a higher proportion of low risk patients were identified (17% of the patients had an ABCD3 score <4 while only 6% had an ABCD2 < 2).

CONCLUSIONS

Although it is preferable that carotid imaging be performed within 24 hours, our data support that an ABCD3 score ≥4 might be used for triaging patients to acute carotid imaging in clinical settings with limited access to carotid imaging. However, our findings should be validated in a larger cohort study.

Population-based study of blood biomarkers in prediction of subacute recurrent stroke

BACKGROUND AND PURPOSE

Risk of recurrent stroke is high in the first few weeks after transient ischemic attack or stroke and clinical risk prediction tools have only limited accuracy, particularly after the hyperacute phase. Previous studies of the predictive value of biomarkers have been small, been done in selected populations, and have not concentrated on the acute phase or on intensively treated populations. We aimed to determine the predictive value of a panel of blood biomarkers in intensively treated patients early after transient ischemic attack and stroke.

METHODS

We studied 14 blood biomarkers related to inflammation, thrombosis, atherogenesis, and cardiac or neuronal cell damage in early transient ischemic attack or ischemic stroke in a population-based study (Oxford Vascular Study). Biomarker levels were related to 90-day risk of recurrent stroke as hazard ratio (95% confidence interval) per decile increase, adjusted for age and sex.

RESULTS

Among 1292 eligible patients, there were 53 recurrent ischemic strokes within 90 days. There were moderate correlations (r=0.40-0.61; P<0.0001) between the inflammatory biomarkers and between the cell damage and thrombotic subsets. Associations with risk of early recurrent stroke were weak, with significant associations limited to interleukin-6 (adjusted hazard ratio, 1.12; 1.01-1.24; P=0.033) and C-reactive protein (adjusted hazard ratio, 1.15; 1.02-1.30; P=0.022) after adjusting for age, sex, hypertension, smoking, and diabetes mellitus although P-selectin seemed to predict stroke after transient ischemic attack (adjusted hazard ratio, 1.28; 1.00-1.63; P=0.046).

CONCLUSIONS

In the largest study to date, we found limited predictive use for early recurrent stroke for a panel of inflammatory, thrombotic, and cell damage biomarkers.

Long-term risk of stroke after transient ischaemic attack: a hospital-based validation of the ABCD² rule

BACKGROUND

The ABCD2 clinical prediction rule is a seven point summation of clinical factors independently predictive of stroke risk. The purpose of this cohort study is to validate the ABCD2 rule in a Bulgarian hospital up to three years after TIA.

METHODS

All consecutive admissions to an emergency department with symptoms of a first TIA were included. Baseline data and clinical examinations including the ABCD2 scores were documented by neurologists. Discrimination and calibration performance was examined using ABCD2 cut-off scores of ≥3, ≥4 and ≥5 points, consistent with the international guidelines. The Hosmer-Lemeshow test was used to examine calibration between the observed and expected outcomes as predicted by ABCD2 score within the logistic regression analysis.

RESULTS

Eighty-nine patients were enrolled to the study with a mean age of 63 years (+/- 12 years). Fifty-nine percent (n = 53) of the study population was male. Seven strokes (7.8%) occurred within the first year and six further strokes within the three-year follow-up period. There was no incident of stroke within the first 90 days after TIA. The rule demonstrated good predictive (OR = 1.58, 95% CI 1.09-2.29) and discriminative performance (AUCROC = 0.72, 95% CI 0.58-0.86), as well as a moderate calibration performance at three years.

CONCLUSION

This validation of the ABCD2 rule in a Bulgarian hospital demonstrates that the rule has good predictive and discriminative performance at three years. The ABCD2 is quick to administer and may serve as a useful tool to assist clinicians in the long-term management of individuals with TIA.

Incorporating diffusion-weighted magnetic resonance imaging into an observation unit transient ischemic attack pathway: a prospective study

BACKGROUND AND PURPOSE

National guidelines advocate for early, aggressive transient ischemic attack (TIA) evaluations and recommend diffusion-weighted magnetic resonance imaging (MRI) for brain imaging. The purpose of this study is to examine clinician compliance, the yield of MRI, and patient-centered clinical outcomes following implementation of an emergency department observation unit (EDOU) clinical pathway incorporating routine MRI into the acute evaluation of patients with TIA.

METHODS

This is a prospective observational study of patients with TIA admitted from the ED. Patients with low-risk TIA were transferred to an EDOU for diagnostic testing including MRI; high-risk patients were directed to hospital admission. Clinical variables, diagnostic tests, and treatment were recorded for all patients. The primary clinical outcome was the rate of stroke or recurrent TIA, determined through telephone follow-up and medical record review at 7 and 30 days.

RESULTS

A total of 116 patients with TIA were enrolled. In all, 92 (79.3%) patients were transferred to the EDOU, of whom 69 (59.5%) were discharged without hospitalization. Compliance with the EDOU pathway was 83 (91.2%) of 92. Magnetic resonance imaging demonstrated acute infarct in 16 (15.7%) of 102 patients. Stroke (n = 2) or TIA (n = 3) occurred in 5 patients with TIA (4.3%, 95% confidence interval: 1.6%-10.0%) within 30 days; no strokes occurred after discharge.

CONCLUSIONS

Implementation of a TIA clinical pathway incorporating MRI effectively encouraged guideline-compliant diagnostic testing; however, patient-important outcomes appear similar to diagnostic protocols without routine MRI. Further study is needed to assess the benefits and costs associated with routinely incorporating MRI into TIA evaluation.

Short-Term Prognosis of Transient Ischemic Attack and Predictive Value of the ABCD(2) Score in Hong Kong Chinese

BACKGROUND

Literature on prognosis of transient ischemic attack (TIA) in Chinese is scarce. The short-term prognosis of TIA and the predictive value of the ABCD(2) score in Hong Kong Chinese patients attending the emergency department (ED) were studied to provide reference for TIA patient management in our ED.

METHODS

A cohort of TIA patients admitted through the ED to 13 acute public hospitals in 2006 was recruited through the centralized electronic database by the Hong Kong Hospital Authority (HA). All inpatients were e-coded by the HA according to the International Classification of Diseases, Ninth Revision (ICD9). Electronic records and hard copies were studied up to 90 days after a TIA. The stroke risk of a separate TIA cohort diagnosed by the ED was compared.

RESULTS

In the 1,000 recruited patients, the stroke risk after a TIA at days 2, 7, 30, and 90 was 0.2, 1.4, 2.9, and 4.4%, respectively. Antiplatelet agents were prescribed in 89%, warfarin in 6.9%, statin in 28.6%, antihypertensives in 39.3%, and antidiabetics in 11.9% of patients after hospitalization. Before the index TIA, the prescribed medications were 27.6, 3.7, 11.3, 27.1, and 9.7%, respectively. The accuracy of the ABCD(2) score in predicting stroke risk was 0.607 at 7 days, 0.607 at 30 days, and 0.574 at 90 days. At 30 days, the p for trend across ABCD(2) score levels was 0.038 (OR for every score point = 1.36, p = 0.040). Diabetes mellitus, previous stroke and carotid bruit were associated with stroke within 90 days (p = 0.038, 0.045, 0.030, respectively). A total of 45.4% of CTs of the brain showed lacunar infarcts or small vessel disease. There was an increased stroke risk at 90 days in patients with old or new infarcts on CT or MRI. Patients with carotid stenosis ≥70% had an increased stroke risk within 30 (OR = 6.335, p = 0.013) and 90 days (OR = 3.623, p = 0.050). Stroke risks at days 2, 7, 30, and 90 in the 289 TIA patients diagnosed by the ED were 0.35, 2.4, 5.2, and 6.2%, respectively.

CONCLUSION

The short-term stroke risk in Hong Kong Chinese TIA patients is low. The administered nonurgent treatment cannot solely explain the favorable outcome, the lower risk can be due to the different pathophysiological mechanisms of stroke between Caucasians and Chinese. The predictive value of the ABCD(2) score is low in our population.