Potential and Failure of the ABCD 2 Score in Stroke Risk Prediction After Transient Ischemic Attack

European Stroke Organisation (ESO) guidelines on management of transient ischaemic attack

The aim of the present European Stroke Organisation Transient Ischaemic Attack (TIA) management guideline document is to provide clinically useful evidence-based recommendations on approaches to triage, investigation and secondary prevention, particularly in the acute phase following TIA. The guidelines were prepared following the Standard Operational Procedure for a European Stroke Organisation guideline document and according to GRADE methodology. As a basic principle, we defined TIA clinically and pragmatically for generalisability as transient neurological symptoms, likely to be due to focal cerebral or ocular ischaemia, which last less than 24 hours. High risk TIA was defined based on clinical features in patients seen early after their event or having other features suggesting a high early risk of stroke (e.g. ABCD2 score of 4 or greater, or weakness or speech disturbance for greater than five minutes, or recurrent events, or significant ipsilateral large artery disease e.g. carotid stenosis, intracranial stenosis). Overall, we strongly recommend using dual antiplatelet treatment with clopidogrel and aspirin short term, in high-risk non-cardioembolic TIA patients, with an ABCD2 score of 4 or greater, as defined in randomised controlled trials (RCTs). We further recommend specialist review within 24 hours after the onset of TIA symptoms. We suggest review in a specialist TIA clinic rather than conventional outpatients, if managed in an outpatient setting. We make a recommendation to use either MRA or CTA in TIA patients for additional confirmation of large artery stenosis of 50% or greater, in order to guide further management, such as clarifying degree of carotid stenosis detected with carotid duplex ultrasound. We make a recommendation against using prediction tools (eg ABCD2 score) alone to identify high risk patients or to make triage and treatment decisions in suspected TIA patients as due to limited sensitivity of the scores, those with score value of 3 or less may include significant numbers of individual patients at risk of recurrent stroke, who require early assessment and treatment. These recommendations aim to emphasise the importance of prompt acute assessment and relevant secondary prevention. There are no data from randomised controlled trials on prediction tool use and optimal imaging strategies in suspected TIA.

Short-term outcomes of Chinese transient ischaemic attack patients in an Emergency department in Hong Kong: Result of management with an agreed protocol with neurologists

Introduction:

Emergency department management of transient ischaemic attack varies from admission for all to outpatient referral. We studied the short-term outcomes of transient ischaemic attack managed with an agreed protocol. Predictors of stroke can be different for Asians and non-Asians. ABCD2 as initial triage of transient ischaemic attack is debatable. The predictive ability of ABCD2 score was studied as well.

Methods:

This was a prospective observational study with consecutive subject recruitment in Emergency department. All transient ischaemic attacks were admitted, hard and e-records of Emergency department, transient ischaemic attack clinic, Medical and Neurosurgical department and general follow-ups in Hospital Authority hospitals were studied up to 1 year. Stroke-day was measured from symptom-onset to time-of-stroke.

Results:

In 18-month period, 124 patients were recruited. The median onset-to-door time was 3.5 h. All computed tomography brain positive findings, except one subdural haematoma, were ischaemic in origin. Six strokes, all disabling, recurred within 90 days, three on day 1–3, two died in 6 months. The stroke risks at 2, 7, 90 days and 1 year were 1.61%, 3.23%, 4.84% and 4.84%, respectively. No significant trend was observed in stroke risk across ABCD2 scores ( p = 0.783) with area under the curve of 0.537 (95% confidence interval = 0.380–0.694; p = 0.762). The short-term stroke risk was associated with atrial fibrillation ( p = 0.002). The median Emergency Medicine ward length of stay was 1.33 days.

Conclusion:

In our Emergency department–based management, the short-term stroke risk of transient ischaemic attack is low, and the predictivity of ABCD2 score in risk stratification cannot be validated. Stroke recurrences were associated with atrial fibrillation. A low ABCD2 could be falsely reassuring. As half of the strokes recurred very early, we recommend admission in the hyperacute phase.

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.

Correlation of ABCD2 score with degree of internal carotid artery stenosis: an observational pilot study

BACKGROUND

ABCD(2) is a validated scoring system that predicts the risk of stroke after a transient ischemic attack (TIA). International guidelines suggest that patients with a low score can be investigated on an outpatient basis. The ABCD2 score, however, cannot identify which patients have significant internal carotid artery (ICA) disease, and this group of patients could benefit from rapid access carotid endarterectomy (RACE). Studies have shown that patients with significant carotid artery disease have a higher risk of neurologic events or recurrent stroke. The aim of this study was to document the range of ABCD2 scores in patients with carotid artery-related TIA, and investigate any correlation between the ABCD2 scores and ICA stenosis.

METHODS

Patients undergoing carotid duplex ultrasound scan for TIA from January 2009 to May 2010 from two vascular units were identified from the vascular database retrospectively. Clinical notes were reviewed and outcomes measures were recorded: ABCD2 scores (age, blood pressure, clinical features, diabetes, and duration) and carotid plaque morphology.

RESULTS

Ninety-seven patients with a mean age of 74 (range 56-90) years had ICA stenoses of ≥50% up to 100%. Fifty-seven patients had an ABCD2 score of ≤4. There was no significant correlation between ABCD2 scores and degree of ICA stenosis nor carotid plaque morphology (P=0.2, r=1.0, and P=1.0, r=0.0007, respectively).

CONCLUSIONS

Because no correlation between ABCD2 scores and the degree of ICA stenosis was found, all patients with carotid territory TIA should undergo urgent imaging of the carotid arteries because a high proportion of these patients may benefit from RACE.

Frequent inaccuracies in ABCD2 scoring in non-stroke specialists' referrals to a daily Rapid Access Stroke Prevention service

The 'accuracy' of age, blood pressure, clinical features, duration and diabetes (ABCD(2)) scoring by non-stroke specialists referring patients to a daily Rapid Access Stroke Prevention (RASP) service is unclear, as is the accuracy of ABCD(2) scoring by trainee residents. In this prospective study, referrals were classified as 'confirmed TIAs' if the stroke specialist confirmed a clinical diagnosis of possible, probable or definite TIA, and 'non-TIAs' if patients had a TIA mimic or completed stroke. ABCD(2) scores from referring physicians were compared with scores by experienced stroke specialists and neurology/geriatric medicine residents at a daily RASP clinic; inter-observer agreement was examined. Data from 101 referrals were analysed (mean age=60.0years, 58% male). The median interval between referral and clinic assessment was 1day. Of 101 referrals, 52 (52%) were 'non-TIAs': 45 (86%) of 52 were 'TIA mimics' and 7 (14%) of 52 were completed strokes. There was only 'fair' agreement in total ABCD(2) scoring between referring physicians and stroke specialists (κ=0.37). Agreement was 'excellent' between residents and stroke specialists (κ=0.91). Twenty of 29 patients scored as 'moderate to high risk' (score 4-6) by stroke specialists were scored 'low risk' (score 0-3) by referring physicians. ABCD(2) scoring by referring doctors is frequently inaccurate, with a tendency to underestimate stroke risk. These findings emphasise the importance of urgent specialist assessment of suspected TIA patients, and that ABCD(2) scores by non-stroke specialists cannot be relied upon in isolation to risk-stratify patients. Inter-observer agreement in ABCD(2) scoring was 'excellent' between residents and stroke specialists, indicating short-term training may improve accuracy.

Can lower risk patients presenting with transient ischaemic attack be safely managed as outpatients?

This study aimed to examine outcome in low risk transient ischaemic attack (TIA) patients presenting to emergency departments (ED) in a regional Australian setting discharged on antiplatelet therapy with expedited neurology review. All patients presenting to Gosford or Wyong Hospital ED with TIA, for whom faxed referrals to the neurology department were received between October 2008 and July 2010, were included in this prospective cohort study. Classification of low risk was based on an age, blood pressure, clinical features, duration of symptoms and diabetes (ABCD2) score <4 and the absence of high risk features, including known carotid disease, crescendo TIA, or atrial fibrillation. Patients with ABCD2 scores > or =4 or with high risk features were discussed with the neurologist on call (a decision regarding discharge or admission was then made at the neurologist's discretion). Patients were investigated with a brain CT scan and/or CT angiography, routine pathology, and an electrocardiogram. All discharged patients were commenced on antiplatelet therapy and asked to follow up with their local medical officer within 7 days. The patients were contacted by the neurology department to arrange follow-up. Our primary outcome was the number of subsequent strokes occurring within 90 days. Of 200 discharged patients for whom referrals were received, three patients had a stroke within 90 days. None of these would have been prevented through hospitalisation. In conclusion, medical assessment, expedited investigation with immediate commencement of secondary prevention and outpatient neurology review may be a reasonable alternative to admission for low risk patients presenting to the ED with TIA.

Varying uses of the ABCD2 scoring system in primary and secondary care: a qualitative study

OBJECTIVES

To explore the usage of the ABCD2 risk stratification score by general practitioners (GPs) and hospital staff during the referral of patients with suspected transient ischaemic attack (TIA) or minor stroke.

DESIGN

Qualitative study using semistructured interviews.

SETTING

Nine general practices and two hospital sites in England (Birmingham and Cambridge).

PARTICIPANTS

Nine GPs and nine hospital staff (two consultants, four nurses, two ultrasonographers and one administrator).

RESULTS

In both sites, clinicians used a referral proforma based around the ABCD2 scoring system for a range of purposes including self-education, to assist emphasising urgency to the patient, as a referral pathway facilitator and as a diagnostic tool. Negative views of its role included potential medicolegal threats, that it was a barrier to appropriate care, and led to misdiagnoses. Despite having differing uses by different clinicians, the ABCD2 proforma was the central means of interprofessional communication in TIA referrals across both sites.

CONCLUSIONS

Understanding how prediction rules are used in practice is key to determining their impact on processes of care and clinical outcomes. In practice, GPs and their colleagues use the ABCD2 score in subtly different ways and it functions as a 'boundary object' by both accommodating these multiple purposes, yet still successfully aiding communication between them.

Incidence of Transient Ischemic Attack and Early Stroke Risk

Background and Purpose—

The importance of transient ischemic attack (TIA) lies on the short-term risk of stroke, and the ABCD2 score may improve early stroke risk prediction. However, population-based studies are still needed. We aimed to provide data on TIA incidence and to evaluate the ABCD2 predictive ability for early recurrent stroke in a population-based study.

Methods—

This study is part of a 2-year prospective community-based registry of all cerebrovascular events in the district of Udine (153 312 inhabitants), Friuli Venezia Giulia region, northeast of Italy, between April 1, 2007 and March 31, 2009. Multiple overlapping sources for finding cases were used, combining hot and cold pursuit.

Results—

We identified 178 TIA, 161 (90.4%) of which were incident. The crude overall annual TIA incidence rate per 1000 residents was 0.52 (95% confidence interval [CI], 0.45–0.61). Incidence rate was 0.45 (95% CI, 0.31–0.65) when standardized to the 2007 Italian population and 0.25 (95% CI, 0.16–0.39) when standardized to the European standard population. Estimates of stroke risk after the index TIA within 2, 7, 30, and 90 days were, respectively, 2.5% (95% CI, 0.7–6.2), 5.6% (95% CI, 2.6–10.3), 6.2% (95% CI, 3.0–11.1), and 11.2% (95% CI, 6.8–17.1). ABCD2 score was strongly associated with stroke occurrence after index TIA: the areas under the receiver operating characteristic curve at 2, 7, 30, and 90 days were, respectively, 0.85 (95% CI, 0.72–0.97), 0.69 (95% CI, 0.56–0.82), 0.69 (95% CI, 0.56–0.85), and 0.76 (95% CI, 0.67–0.86). No patients with an ABCD2 score <4 had a stroke within the 90-day follow-up period.

Conclusions—

This study adds new data on TIA incidence and prognosis and it further validates the ability of the ABCD2 score to identify patients at early risk for stroke.