ABCD² Score for TIA
The ABCD2 score can help physicians risk stratify stroke in patients presenting with a TIA.
The ABCD2 score was developed to help physicians risk stratify patients presenting with a TIA for how likely they are to suffer a subsequent stroke.
- The largest prospective study of using the ABCD2 score in the emergency department found that the score performed poorly (low sensitivity for identifying low risk patients, low specificity for identifying high risk patients).
- Multiple studies have shown that as the ABCD2 score increases the risk of a subsequent stroke also increases.
- Patients with a low baseline risk of stroke (≤ 2%) with a low ABCD2 score (0-2) are at low risk for having a stroke within the next 7 days (0.4-0.8%).
Points to keep in mind:
- The ABCD2 score was developed in the outpatient (non-emergency department) setting.
- It has been shown to have lower accuracy when used by non-specialists (primary care or emergency physicians).
- The ABCD2 has less impact on risk stratification when applied in settings where the patients were at low baseline risk of stroke.
There are approximately 250,000 transient ischemic attacks (TIAs) diagnosed in the United States annually.
The ABCD2 score may help physicians identify those patients with TIA who are at very low risk of stroke and may be appropriate for an outpatient work-up vs. those who are at increased risk and may benefit from hospital admission.
Please fill out required fields.
Consider further imaging modalities including MRI and carotid ultrasound.
Consider consulting Neurology to help determine whether the patient would benefit from further inpatient evaluation or to expedite outpatient follow-up when appropriate.
In patients who are determined at high risk for developing a stroke:
- Consult Neurology.
- Consider obtaining an MRI and other appropriate vascular and embolic imaging.
- Have a lower threshold to admit to the patient for further evaluation.
In patients who are determined to be at low risk of developing a stroke in the short term:
- Arrange expedited evaluation as an outpatient with the goal of obtaining the relevant studies and consultations within 24 hours.
- The ABCD2 score should not be used as a substitute for clinical judgement or decision making.
- In populations with a low baseline stroke risk, a low ABCD2 score (0-2) correlates with a less than 1% risk of stroke within the next week. These patients may be appropriate for expedited outpatient evaluation.
- In centers where computed tomography and carotid ultrasound studies are performed in collaboration with a stroke service, adding the ABCD2 score to the evaluation appears unnecessary.
Addition of the selected points.
Facts & Figures
See formula table, below:
|Age ≥ 60 years||Y/N||+1|
|BP ≥ 140/90 mmHg||Y/N||+1|
|Clinical features of the TIA||Unilateral Wwakness||+2|
|Speech disturbance without weakness||+1|
|Duration of symptoms||< 10 minutes||0|
|≥ 60 minutes||+2|
|History of diabetes||Y/N||+1|
- In one study of 713 patients reviewed by an expert neurologist, 642 (90%) were judged to likely have experienced a true TIA. (Josephson 2008)
- Ninety-day stroke risk was 24% (95% CI, 20% to 27%) in the group judged to have experienced a true TIA and 1.4% (0% to 7.6%) in the group judged to not have a true TIA (P<0.0001). (Josephson 2008)
- ABCD2 scores were higher in those judged to have a true TIA compared with others (P=0.0001). In the group judged to have a true TIA, 90-day stroke risk increased as ABCD2 score increased (P<0.0001). (Josephson 2008)
- In its derivation study, the ABCD2 score classified 21% of patients as high risk (score 6-7, 8.1% 2-day stroke risk), 45% as moderate risk (score 4-5, 4.1% 2-day stroke risk), and 34% as low risk (score 0-3, 1.0% 2-day stroke risk). (Johnston 2007)
- The largest ED-based study was a prospective cohort study of 2,056 subjects and found that the ABCD2 score performed poorly in the acute setting. (Perry 2011)
- In high risk patients (score >5) the ABCD2 score was only 31.6% sensitive identifying patients who suffered a stroke within 7 days. (Perry 2011)
- Using the low risk cut-off recommended by AHA (score >2) the ABCD2 score had a specificity of only 12.5% for stroke within 7 days. (Perry 2011)
- This study found the the ABCD2 score was incorrectly calculated in the ED in 1/3 of patients. (Perry 2011)
- A meta-analysis of 33 studies including 16,070 subjects found that the ABCD2 score performed poorly in patients with high baseline stroke risk, and was only marginally better when applied to low risk patients. (Sanders 2012)
- A review of this meta-analysis noted that the majority of the included studies were retrospective and that only 8 of the 33 included patients presenting to the ED (this subgroup was not separately analysed). (Lee 2013)
- The authors note that the poor performance of the ABCD2 score in the ED setting, combined with difficulties in arranging the necessary imaging and specialty follow-up within the AHA recommended 24-hour window, that most ED physicians were likely to choose to perform a rapid evaluation of TIA patients (imaging, possible neurology consultation) regardless of the ABCD2 score. (Lee 2013)
- A prospective observational study of 637 patients presenting to the ED found that the ABCD2 score did not add incremental value beyond an ED evaluation that included central nervous system and carotid artery imaging in the ability to risk-stratify patients with transient ischemic attack in the study's cohort. (Stead 2010)
- In this population of patients with TIA patients, a rapid ED-based outpatient protocol that included early carotid imaging and treatment when appropriate, found that the rate of stroke was independent of ABCD2 risk stratification. (Stead 2010)
Original/Primary ReferenceJohnston SC, Rothwell PM, Nguyen-Huynh MN, Giles MF, Elkins JS, Bernstein AL, Sidney S. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet. 2007 Jan 27;369(9558):283-92.
ValidationJosephson SA, Sidney S, Pham TN, Bernstein AL, Johnston SC. Higher ABCD2 score predicts patients most likely to have true transient ischemic attack. Stroke. 2008 Nov;39(11):3096-8. doi: 10.1161/STROKEAHA.108.514562. Epub 2008 Aug 7.
Other ReferencesRothwell PM, Giles MF, Flossmann E, Lovelock CE, Redgrave JN, Warlow CP, Mehta Z. A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack. Lancet. 2005 Jul 2-8;366(9479):29-36.Sanders LM, Srikanth VK, Blacker DJ, Jolley DJ, Cooper KA, Phan TG.Performance of the ABCD2 score for stroke risk post TIA: meta-analysis and probability modeling. Neurology. 2012 Sep 4;79(10):971-80. doi: 10.1212/WNL.0b013e31825f9d02. Epub 2012 Jun 13. PubMed PMID: 22700810.Stead LG, Suravaram S, Bellolio MF, Enduri S, Rabinstein A, Gilmore RM, Bhagra A, Manivannan V, Decker WW. An assessment of the incremental value of the ABCD2 score in the emergency department evaluation of transient ischemic attack. Ann Emerg Med. 2011 Jan;57(1):46-51. doi: 10.1016/j.annemergmed.2010.07.001. Epub 2010 Sep 19. PubMed PMID: 20855130.Perry JJ, Sharma M, Sivilotti ML, Sutherland J, Symington C, Worster A, Émond M, Stotts G, Jin AY, Oczkowski WJ, Sahlas DJ, Murray HE, MacKey A, Verreault S, Wells GA, Stiell IG. Prospective validation of the ABCD2 score for patients in the emergency department with transient ischemic attack. CMAJ. 2011 Jul 12;183(10):1137-45. doi: 10.1503/cmaj.101668. Epub 2011 Jun 6. PubMed PMID: 21646462.
From the Creator
We designed the ABCD2 score to be a simple clinical prediction tool for use in triaging patients presenting with acute TIA. It was based on risk factors identified in cohorts from Northern California and Oxford, England, optimized to predict the 2-day stroke risk. It was initially validated in independent cohorts from those two locations but has now been validated in many other populations. It works pretty well but is far from perfect. Imaging information, such as whether an acute infarction is present, can also be very useful for prognostication and is not incorporated into the score. Although the score has been incorporated into guidelines for hospital admission and more detailed evaluations, it should not be used in place of clinical judgment. For example, a young person with a history of IV drug use and a new murmur presenting with a brief episode of facial tingling might have an ABCD2 score of 0 yet may be at high short-term risk of stroke.
About the Creator
S. Claiborne Johnston, MD, PhD is the Director of the Stroke Service at the University of California, San Francisco, where he is Professor of Neurology and Epidemiology and Director of the Clinical and Translational Science Institute (CTSI). He has published extensively in the prevention and treatment of stroke and transient ischemic attack. Dr. Johnston has been honored with multiple awards including the American Academy of Neurology’s Pessin Prize for Stroke Leadership.
To view Dr. S. Claiborne Johnston's publications, visit PubMed