Letter by Purroy and Kelly Regarding Article, “A Prospective Cohort Study of Patients With Transient Ischemic Attack to Identify High-Risk Clinical Characteristics”
To the Editor:
Perry et al1 should be congratulated for their large and meticulous multicentric study of stroke risk after transient ischemic attack (TIA). However, we wish to discuss some issues raised in their article.
Several principles underlie the development of a prognostic score for use in daily clinical practice. It should be derived in large samples similar to the population in which it is intended for use. It should be robustly validated in independent large patient samples drawn from clinical settings similar to the derivation sample, using measures of discrimination (eg, the C-statistic) and calibration. To enhance acceptability for busy clinicians, ideally it should be straightforward to remember and apply to individual patients. It should have demonstrated use in routine practice, for clinical decision making and improving use of healthcare resources. When a new score is proposed, its added value over the existing score should be demonstrated using measures of reclassification improvement and statistical evidence of improved discrimination.
In TIA, the ABCD2 score2 (intended for primary care risk stratification of patients with transient neurological symptoms) has been independently validated in ≥9800 patients, with moderate discrimination at 7 days (pooled area under curve of 0.72; confidence intervals [0.63–0.82]). The ABCD3-I score,3 which incorporates carotid and early brain imaging for use in hospital settings, has been independently validated in >2500 patients in cohorts from Ireland, United Kingdom, Spain, China, and Japan, with improved discrimination for stroke risk at 7 days and improved risk reclassification reported in some cohorts compared with ABCD2. Although these data are encouraging, further independent studies examining validity, safety, feasibility, and clinical use of ABCD3-I–based TIA risk stratification are needed.
Allowing for some additional items and differences in definitions, the Canadian TIA Score contains similar variables to those already included in the existing ABCD3-I model, including infarction on brain computed tomography. For immediate initiation of intensive stroke prevention after TIA, the diagnostic workup should include not only brain imaging but also vascular imaging. Observational studies have clearly established that patients with intracranial and extracranial large artery stenosis are at high risk of early stroke recurrence.4 The early detection of these high-risk patients offers an opportunity to prevent recurrent stroke by early carotid revascularization or intensive medical therapy. In this context, it is surprising that early vascular imaging was not included, and no detailed analysis to compare their model with existing risk prediction models was performed. It would also be interesting to evaluate multiple TIAs, which are a risk marker for early stroke independently of the pathogenetic subtype.5
As another TIA risk score is proposed, the bigger picture is the risk of score fatigue among practicing clinicians who treat patients with acute TIA, and whose main requirement is a robustly validated, clinically useful score to guide management decisions in the community clinic or emergency department, similar to the CHADS2 VA2Sc score in atrial fibrillation. Rather than new scores for hospital-based TIA risk stratification, we propose that the immediate priority should be more robust external validation of ABCD3-I, investigation of the safety and use of acute TIA management algorithms based on ABCD3-I, and research on clinical scenarios in which it may be inappropriate for use (such as posterior circulation TIA or TIA in young adults).
Francisco Purroy, MD, PhD
Stroke Unit, Hospital Universitari Arnau de Vilanova
Clinical Neurosciences Group IRB Lleida
Universitat de Lleida
Peter J. Kelly, MD, MS, FRCPI
Neurovascular Unit for Translational
and Therapeutics Research
Mater University Hospital, Dublin, Ireland
Dr Kelly is the Principal Investigator on a significant research grant from the Health Research Board of Ireland on Risk Stratification after transient ischemic attack and stroke. The other author reports no conflict.
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- © 2014 American Heart Association, Inc.
- Perry JJ,
- Sharma M,
- Sivilotti ML,
- Sutherland J,
- Worster A,
- Émond M,
- et al
- Purroy F,
- Montaner J,
- Molina CA,
- Delgado P,
- Ribo M,
- Alvarez-Sabín J
- Purroy F,
- Jiménez Caballero PE,
- Gorospe A,
- Torres MJ,
- Alvarez-Sabin J,
- Santamarina E,
- et al