Danny R. Rose, Jr., MD

Cooray C, Mazya M, Bottai M, Dorado L, Skoda O, Toni D, et al. External Validation of the ASTRAL and DRAGON Scores for Prediction of Functional Outcome in Stroke. Stroke. 2016

Given that functional outcome is one of the most commonly used parameters in studying acute stroke treatment, developing accurate prognostication scores would greatly facilitate treatment decisions and improve communicating expectations to patients and families. Cooray et al. sought to validate the two most recently developed scores designed to predict functional outcome at three months, one studied in unselected acute stroke patients (ASTRAL) and the other in acute stroke patients treated with iv-tPA (DRAGON) using the SITS-International Stroke Thrombolysis Register (ISTR), a  global stroke thrombolysis database. Outcomes were dichotomized into modified Rankin Scale (mRS) 0-2 and 3-6 as were done in both of the initial studies, and the area under the curve (AUC) of the receiver operating characteristic (ROC) was used in both scores to assess the overall predictive and discriminative performance.

The ASTRAL score was developed in a single center stroke cohort using multivariate logistic regression analysis. It consists of 6 clinical parameters: age at stroke onset (1 point per 5 years), baseline National Institutes of Health Stroke Scale (NIHSS) score (1 point per NIHSS point), time from symptom onset to admission > 3 hours (2 points), any stroke-related visual field defect (2 points), acute blood glucose >7.3 or <3.7 mmol/L (1 point) and decreased level of consciousness based on item 1a on the NIHSS (3 points). A total of 36,131 iv-tPA treated patients with complete data for the ASTRAL score were registered in the SITS-ISTR database. The main differences between the SITS-ISTR and ASTRAL cohorts were higher mean baseline stroke severity (NIHSS 12 vs 9) and a lower proportion of functional independence at 3 months in SITS, which is likely explained by the higher severity. The AUC-RPC value for functionally dependent outcome (mRS 3-6) of the ASTRAL score using this cohort was 0.790 (95% CI 0.786-0.795). Over the rante of scores, the largest discrepancy between the observed and predicted outcome was found to be 11%.

The DRAGON score was developed in a single center cohort of acute ischemic stroke patients treated with iv-tPA using similar statistical design to the ASTRAL score. It is a 10 point scale and the included parameters are hyperdense cerebral artery sign (1 point) and early infarct signs (1 point) on baseline CT, pre-stroke mRS score >1 (1 point), age (<65 years = 0 points, 65-79 years = 1 point, >80 years ≥ 2 points), acute blood glucose >8 mmol/L (1 point), time from symptom onset to treatment >90 min (1 point) and NIHSS score (0-4 = 0 points, 5-9 = 1 point, 10-15 = 2 points and >15 = 3 points). A total of 33,716 iv-tPA treated patients with complete data for the DRAGON score were registered in the SITS-ISTR database. The main differences between the SITS and DRAGON cohorts were higher median baseline stroke severity (NIHSS 12 vs 9), lower proportion of early infarct signs (16.5% vs 30.6%) and higher onset-to-treatment time in the SITS cohort. The AUC-ROC value for functionally dependent outcome on the DRAGON score using the SITS-ISTR cohort was 0.77 (95% CI 0.769-0.779). The largest discrepancy between observed and predicted outcome was close to 17%.


Despite the limitations of using a retrospective analysis, the authors’ validation of the ASTRAL and DRAGON scores suggest an acceptable prognostic value for both. Despite being designed and validated using an unselected cohort that included thrombolysed and non-thrombolysed patients, the ASTRAL score showed a similar discriminative performance to the DRAGON score in this study. Future studies involving these scores would benefit from collecting data prospectively and including patients receiving endovascular therapy.