What is the accuracy of the ASTRAL (Astral Stroke Risk Assessment Tool) stroke prediction tool in adults with hypertension, diabetes, atrial fibrillation, or other conditions that increase stroke risk?

ASTRAL Score Accuracy for Stroke Prediction

The ASTRAL score demonstrates good to excellent accuracy for predicting functional outcomes and mortality after acute ischemic stroke, but it is NOT designed for primary stroke prevention in at-risk populations—it is a post-stroke prognostic tool, not a pre-stroke risk assessment instrument.

Critical Distinction: ASTRAL vs. Primary Prevention Tools

The ASTRAL (Acute Stroke Registry and Analysis of Lausanne) score is fundamentally different from primary prevention risk assessment tools:

• ASTRAL is a post-stroke prognostic tool used after acute ischemic stroke has already occurred to predict functional outcomes and mortality 1, 2, 3
• For primary stroke prevention in patients with hypertension, diabetes, or atrial fibrillation, guidelines recommend the Framingham Stroke Profile, AHA/ACC CV Risk Calculator, or CHADS2/CHA2DS2-VASc scores instead 4, 5
• The American Heart Association explicitly states that "no risk stratification systems have been generally recommended for use after stroke" for secondary prevention, highlighting the gap ASTRAL attempts to fill 6

ASTRAL Score Performance for Post-Stroke Prognosis

Short-Term Outcomes (3 months)

• ASTRAL demonstrates excellent discriminative ability for 3-month functional outcomes with an area under the ROC curve (AUROC) of 0.78-0.79 in large validation studies 7
• In comparative analyses of 8 different stroke prognostic scales using 10,777 patients, ASTRAL significantly outperformed all other scales including iSCORE, PLAN, SOAR, and THRIVE for predicting modified Rankin Scale outcomes 7

Long-Term Outcomes (5 years)

• ASTRAL reliably predicts 5-year functional outcomes with AUROC of 0.89 (95% CI 0.88-0.91) for unfavorable outcomes (modified Rankin Scale 3-6) 2
• For 5-year mortality prediction, ASTRAL achieves AUROC of 0.81 (95% CI 0.78-0.83) and independently predicts mortality with hazard ratio 1.09 per point increase 2
• Survival probability decreases significantly with increasing ASTRAL score quartiles over 5-year follow-up 2

Specific Clinical Applications

• ASTRAL predicts symptomatic hemorrhagic transformation after revascularization (IVT/mechanical thrombectomy) with AUROC of 0.88, showing significantly higher scores in patients who developed hemorrhagic transformation (median 36 vs. 24 points, p<0.001) 1

Machine Learning Comparisons

• Deep neural network models can marginally improve upon ASTRAL with AUROC of 0.888 versus 0.839 for ASTRAL (p<0.001), though this requires more complex computational approaches 3
• When limited to only the 6 variables used in ASTRAL, machine learning models show no significant advantage over the traditional ASTRAL score 3
• At admission, ASTRAL performs comparably to advanced machine learning (AUROC ~0.77-0.81), but adding features available at later time points can increase machine learning model performance above 0.90 8

Clinical Limitations and Caveats

Important Pitfalls

• ASTRAL has only modest prognostic accuracy (AUROC 0.78-0.79) which "may not be sufficient as a basis for clinical decision-making" according to large-scale validation 7
• The score is NOT designed for large vessel occlusion detection—use NIHSS, RACE, LAMS, or CPSSS instead for this purpose 6
• Current risk stratification schemes including ASTRAL ignore clinically important outcomes such as functional decline, disability progression, and dementia 6

Context-Specific Use

• For atrial fibrillation patients requiring primary prevention, use CHADS2 or CHA2DS2-VASc scores which assign points for heart failure (1), hypertension (1), age ≥75 years (1), diabetes (1), and prior stroke/TIA (2) 4
• For general primary prevention, the Framingham Stroke Profile incorporates age, systolic blood pressure, hypertension, diabetes, smoking, cardiovascular disease, atrial fibrillation, and left ventricular hypertrophy 4
• The AHA/ACC CV Risk Calculator is reasonable for identifying individuals who could benefit from therapeutic interventions beyond single risk factor treatment 4

Bottom Line for Clinical Practice

Use ASTRAL only after acute ischemic stroke has occurred to predict functional outcomes and guide prognostic discussions with patients and families. For primary stroke prevention in patients with hypertension, diabetes, or atrial fibrillation, use the Framingham Stroke Profile, AHA/ACC CV Risk Calculator, or CHADS2/CHA2DS2-VASc scores as recommended by AHA/ASA guidelines 4, 5.