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    ASTRAL Score for Ischemic Stroke

    Predicts 90-day poor outcome in patients with acute ischemic stroke.
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    INSTRUCTIONS

    Use in patients with acute ischemic stroke admitted within 24 hours of stroke onset.
    When to Use
    Pearls/Pitfalls
    Why Use

    Patients with acute ischemic stroke admitted within 24 hours of stroke onset.

    • The ASTRAL Score uses clinical characteristics and laboratory testing to predict the likelihood that a given patient with acute ischemic stroke will have a Modified Rankin Scale result of 3–6 at 90 days after stroke.
    • Developed to predict a dichotomous outcome, not a discrete Modified Rankin Scale score at 90 days.
    • Does not predict mortality or degree of improvement from any form of rehabilitation.
    • Should not be used as a surrogate for stroke severity.
    • Can provide additional information on medium-term functional outcome in patients that have suffered acute ischemic stroke, in addition to clinical judgment based on relevant clinical and laboratory variables.
    • Does not need neuroimaging data to calculate.
    • Can be used to adjust for functional outcome in multivariate models in acute stroke-related research studies.
    • Can serve as a selection criterion for cohorts in acute stroke-related research studies.
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    Next Steps
    Evidence
    Creator Insights

    Advice

    • Acute ischemic stroke is a neurological emergency that is amenable to time-sensitive treatments (e.g. tPA, mechanical thrombectomy) if certain clinical conditions are met.
    • Neurological consultation should be obtained immediately in suspected cases of acute ischemic stroke.
    • Should not be used as a substitute for clinical judgment and is intended for use as an adjunct to medical decision-making.

    Management

    • In cases of suspected ischemic stroke, the following is recommended:
      • STAT neurological consultation.
      • STAT CT head without contrast.
      • STAT laboratory testing (complete blood count, PT/INR/aPTT, basic metabolic panel, type & screen, troponin-I).
      • Consider STAT CT angiogram of the head & neck in cases of suspected large-vessel occlusion (LVO) presenting in the acute setting.

    Critical Actions

    • Intravenous tissue plasminogen activator (IV tPA) is the standard-of-care treatment for adult patients presenting with acute ischemic stroke within 4.5 hours of symptom onset, if no exclusion criteria are met.
    • Mechanical thrombectomy is the standard-of-care treatment for selected adult patients presenting with acute ischemic stroke due to LVO presenting in the acute setting.
    • Note that the appropriateness of patient for endovascular intervention depends on multiple factors, such as time since onset, neuroimaging, baseline functional status, and others.
    • Appropriateness for intravenous thrombolysis or mechanical thrombectomy should be determined by neurological/neurosurgical consultant whenever available.

    Formula

    Addition of the selected points: 

    Age

    1 point for every 5 years

     --

    Severity

    1 point for every admission NIHSS point

     --

    Time delay between symptom onset or last proof of good health and admission

    2 points if >3 hours

    0 points if ≤3 hours

    Range of visual fields (new visual field defect)

    2 points if yes

    0 points if no

    Glucose at admission

    1 point if >7.3 or <3.7 mmol/L

    0 points if 3.7-7.3 mmol

    Level of consciousness

    3 points if impaired

    0 points if normal

    Evidence Appraisal

    The ASTRAL (Acute Stroke Registry and Analysis of Lausanne) Score was originally developed in a study by Ntaios et al in 2012, which identified six clinical and laboratory predictors of poor functional outcome, defined as a Modified Rankin Scale result of 3–6 at 90 days in a registry of patients with acute ischemic stroke from Lausanne, Switzerland (n = 1,645).

    The AUC was 0.85 in the derivation cohort; this study also had an internal validation of the score using separate stroke registry cohorts from Athens (n = 1,659; AUC 0.94) and Vienna (n = 653; AUC 0.77). The Hosmer-Lemeshow goodness-of-fit test was non-significant in all cohorts, indicating a well-calibrated score (derivation, p = 0.43; Athens, p = 0.22; Vienna, p = 0.49).

    The ASTRAL Score was determined to have the following specificities, sensitivities, and positive and negative predictive values for determining poor functional outcome (mRS 3–6) at 90 days at the cut-points below. Note: Due to low numbers of observations, numbers associated with the highest ASTRAL Scores should be interpreted with caution.

    ASTRAL Score cut-point

    Sensitivity, %

    Specificity, %

    Positive predictive value, %

    Negative predictive value, %

    18

    97.3

    28.5

    40.7

    95.4

    23

    84.8

    65.9

    55.6

    89.6

    31

    59.6

    90.2

    75.5

    81.6

    38

    31.3

    97.5

    86.5

    73.8

    43

    17.4

    99.6

    96.0

    70.5

    The ASTRAL Score was subsequently validated by Liu et al (2013) in a Chinese cohort (n = 3,755). The AUC was comparable to that determined in the original derivation study by Ntaios et al (AUC 0.82, 95%CI, 0.81-0.83).

    In the largest validation study of the ASTRAL Score to date, Cooray et al (2016) examined the prediction of 90 day functional outcomes in patients with acute ischemic stroke treated with IV thrombolysis as part of the SITS-ISTR (Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register; n = 36,131). While the AUC of the ASTRAL score was 0.79 (95%CI, 0.786 – 0.795), the SITS-ISTR cohort had a higher mean NIH stroke scale (12.2 vs. 8.9, p<0.0001), a shorter time from onset to assessment (82.2 min vs. 395.8 min, p<0.0001) and a smaller proportion of patients achieving mRS 0-2 at 90 days (57.4% vs 66%) than the original derivation cohort.

    Multiple external validations have been conducted for the ASTRAL Score’s ability to predict post-stroke outcomes not examined in the original ASTRAL Score derivation study, including:

    Literature

    Dr. George Ntaios

    About the Creator

    George Ntaios, MD, PhD, is an assistant professor of internal medicine at the University of Thessaly in Larissa, Greece. He is co-chair of the Guidelines Committee of the European Stroke Organization and Secretary General of the Hellenic Stroke Organization. Dr. Ntaios is an active researcher, focusing mainly on secondary stroke prevention and stroke prognosis.

    To view Dr. George Ntaios's publications, visit PubMed

    Dr. Patrik Michel

    About the Creator

    Patrik Michel, MD, is a professor in the department of neurology at the University of Lausanne in Switzerland. He is chief of the Cerebrovascular Center there, which he also established. Dr. Michel is active in many professional organizations, including the European Stroke Organization and the World Stroke Organization.

    To view Dr. Patrik Michel's publications, visit PubMed

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