Elsevier

The Lancet

Volume 366, Issue 9479, 2–8 July 2005, Pages 29-36
The Lancet

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A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack

https://doi.org/10.1016/S0140-6736(05)66702-5Get rights and content

Summary

Background

Effective early management of patients with transient ischaemic attacks (TIA) is undermined by an inability to predict who is at highest early risk of stroke.

Methods

We derived a score for 7-day risk of stroke in a population-based cohort of patients (n=209) with a probable or definite TIA (Oxfordshire Community Stroke Project; OCSP), and validated the score in a similar population-based cohort (Oxford Vascular Study; OXVASC, n=190). We assessed likely clinical usefulness to front-line health services by using the score to stratify all patients with suspected TIA referred to OXVASC (n=378, outcome: 7-day risk of stroke) and to a hospital-based weekly TIA clinic (n=210; outcome: risk of stroke before appointment).

Results

A six-point score derived in the OCSP (age [⩾60 years=1], blood pressure [systolic >140 mm Hg and/or diastolic ⩾90 mm Hg=1], clinical features [unilateral weakness=2, speech disturbance without weakness=1, other=0], and duration of symptoms in min [⩾60=2, 10–59=1, <10=0]; ABCD) was highly predictive of 7-day risk of stroke in OXVASC patients with probable or definite TIA (p<0·0001), in the OXVASC population-based cohort of all referrals with suspected TIA (p<0·0001), and in the hospital-based weekly TIA clinic-referred cohort (p=0·006). In the OXVASC suspected TIA cohort, 19 of 20 (95%) strokes occurred in 101 (27%) patients with a score of 5 or greater: 7-day risk was 0·4% (95% CI 0–1·1) in 274 (73%) patients with a score less than 5, 12·1% (4·2–20·0) in 66 (18%) with a score of 5, and 31·4% (16·0–46·8) in 35 (9%) with a score of 6. In the hospital-referred clinic cohort, 14 (7·5%) patients had a stroke before their scheduled appointment, all with a score of 4 or greater.

Conclusions

Risk of stroke during the 7 days after TIA seems to be highly predictable. Although further validations and refinements are needed, the ABCD score can be used in routine clinical practice to identify high-risk individuals who need emergency investigation and treatment.

Introduction

Ischaemic strokes are frequently preceded by a transient ischaemic attack (TIA).1 However, because of methodological problems in early studies of prognosis, the immediate risk of stroke after a TIA was underestimated for many years.2, 3 Hospital-based and population-based cohort studies have reported 7-day risks of stroke of up to 10%.4, 5, 6, 7, 8 However, there is substantial international variation in how patients with suspected TIA are managed in the acute phase, with some health-care systems providing immediate emergency inpatient care and others providing non-emergency outpatient clinic assessment,9, 10 and there is little consensus about which strategy is most cost-effective.11, 12 North American and UK guidelines simply state that all patients in whom a diagnosis of TIA is suspected should be assessed and investigated within 7 days,13, 14 although this aim is frequently not achieved in practice. However, the key question is not, in fact, whether emergency inpatient care or non-emergency outpatient care is most appropriate. Rather, it is: for which patients is emergency assessment needed, and which patients can be appropriately managed in a non-emergency outpatient setting? Only about 50% of patients referred for specialist assessment with suspected TIA have the diagnosis confirmed, and so even if the 7-day stroke risk after a TIA is as high as 10%, 95% of referrals will not have a stroke in that period.

Validated models are available for long-term risk of stroke after TIA or minor stroke,15, 16, 17 and there are some unvalidated reports of predictors of stroke at 3 months or 1 year after a TIA,4, 7, 8 but the practical clinical requirement is for prediction of stroke during the first few days after the event, for which there are currently no published models. We therefore aimed to derive and validate a simple risk score to predict stroke during the first 7 days after a TIA with three potential uses in mind: to allow primary-care doctors and other front-line physicians to identify which of the patients in whom they suspect a diagnosis of TIA should be referred-on for assessment as an emergency; to allow secondary-care physicians to determine which patients with probable or definite TIA need emergency investigation and treatment; and to allow public education about the need for medical attention after a TIA to focus on the specific symptoms and characteristics that identify high-risk individuals.

Section snippets

Derivation of a simple risk score

We derived the score in the population-based cohort of TIA patients in the Oxfordshire Community Stroke Project (OCSP). The methods of the OCSP have been reported elsewhere.18, 19 Briefly, a population of about 105 000 registered with 50 family doctors in ten practices in Oxfordshire, UK, was studied. All patients with a possible diagnosis of TIA during the study period (1981–86) were reported to a study neurologist and assessed as soon as possible after the event. The characteristics of the

Results

Table 1 shows the baseline characteristics of the OCSP and OXVASC cohorts of patients with probable or definite TIA. Data were missing on duration of TIA in four patients in OCSP, three of whom also had missing data on clinical features, leaving 205 of 209 (98%) patients with complete data (table 1). Complete data were available for 188 of 190 (99%) OXVASC patients. The OXVASC cohort was older than the OCSP cohort (p=0·002), had a higher proportion of women (p=0·02), higher rates of previously

Discussion

We have derived and validated a simple score to predict stroke in the 7 days after a TIA, based on age, blood pressure, clinical features, and duration of symptoms. We used data from three rigorous clinical studies. OXVASC and OCSP are two of only a very few prospective, truly population-based studies of TIA with high levels of ascertainment and detailed assessment by neurologists. The hospital-referred clinic series was also valuable in that, unlike other such studies, all referrals were

References (39)

  • A Coull et al.

    Early risk of stroke after a TIA or minor stroke in a population-based incidence study

    BMJ

    (2004)
  • MD Hill et al.

    The high risk of stroke immediately after transient ischemic attack. A population-based study

    Neurology

    (2004)
  • LD Lisabeth et al.

    Stroke risk after transient ischaemic attack in a population-based setting

    Stroke

    (2004)
  • SC Johnston et al.

    Practice variability in management of transient ischaemic attacks

    Eur Neurol

    (1999)
  • LB Goldstein et al.

    New transient ischemic attack and stroke: outpatient management by primary care physicians

    Arch Intern Med

    (2000)
  • G Gubitz et al.

    What is the cost of admitting patients with transient ischaemic attacks to hospital?

    Cerebrovasc Dis

    (1999)
  • B Ovbiagele et al.

    In-hospital initiation of secondary stroke prevention therapies yield high rates of adherence at follow-up

    Stroke

    (2004)
  • The Intercollegiate Working Party for Stroke. National Clinical Guidelines for Stroke

    (2004)
  • PA Wolf et al.

    Preventing ischemic stroke in patients with prior stroke and transient ischemic attack: a statement for healthcare professionals from the Stroke Council of the American Heart Association

    Stroke

    (1999)
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