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ABCD² Score (TIA Stroke Risk)

The ABCD² score predicts short-term stroke risk after a transient ischaemic attack using five clinical features: Age, Blood pressure, Clinical presentation, Duration, and Diabetes.

inputs

✓ when to use

Use to stratify urgency of specialist TIA evaluation. All TIA patients need urgent assessment, but ABCD² helps prioritise. In current practice, most guidelines recommend rapid assessment (within 24 hours) regardless of score, with imaging and secondary prevention initiated immediately.

✗ when not to use

ABCD² was designed for initial triage, not for replacing clinical assessment. A low ABCD² score does NOT exclude high-risk features (e.g., AF, carotid stenosis, crescendo TIA). Modern TIA pathways emphasise rapid imaging-based assessment (CT/MR angiography, cardiac monitoring) over score-based triage alone. Not validated for posterior circulation TIA (which may present with atypical features scored as 0).

clinical pearls

  • Modern TIA management has shifted away from ABCD² as the primary triage tool. Current guidelines emphasise that ALL suspected TIA patients need urgent assessment (within 24 hours) with vascular imaging, cardiac monitoring, and immediate secondary prevention — regardless of ABCD² score.
  • A low ABCD² score can be falsely reassuring. Posterior circulation TIAs (vertigo, ataxia, diplopia) may score 0–1 but still have significant stroke risk. Crescendo TIA and large-vessel stenosis are not captured by the score.
  • The most impactful clinical action after TIA is starting secondary prevention immediately: antiplatelet therapy (aspirin ± clopidogrel for 21 days per CHANCE/POINT trials), statin, and BP control. This reduces 90-day stroke risk by >50%.
  • ABCD² does not include imaging findings. An ABCD² score of 2 with 70% internal carotid artery stenosis is a vascular emergency. Always obtain vascular imaging urgently.
  • Duration of symptoms can be difficult to determine precisely. If uncertain, err on the side of the longer duration category.

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UK clinical guidanceStroke and TIA (initial assessment + urgent actions)