Validation of the DRAGON Score in a North American Cohort

Objective: To provide external validation of the DRAGON Score for predicting outcome after intravenous thrombolysis Methods: A retrospective chart analysis was performed in stroke patients receiving IV-tPA within the 4.5 hour time window from January 2009 to September 2013. A total of 149 patients were included in the analysis. DRAGON scores were calculated for each patient and compared to modified Rankin scores (mRS) at 90-day follow up. Comparison of baseline patient characteristics to the original derivation cohort was made using Chi Square derived p-values for analysis where appropriate. Validity of the model was determined using area under the receiver operating characteristic (ROC) curve analysis for good and bad outcomes. Results: Proportions of patients with good outcomes (mRS of 0-2) were 100%, 89%, 75%, 5%, 0% and 0% for DRAGON Scores 0-1, 2, 3, 7, 8 and 9-10 respectively. Proportions of patients with miserable outcome (mRS of 5-6) were 0%, 5%, 4%, 82%, 100%, 80% for DRAGON Scores 0-1, 2, 3, 7, 8 and 9-10 respectively. AUC-ROC was 0.93 for our model. When using the score to evaluate only good or bad outcomes the AUC-ROC was 0.88 and 0.89, respectively. Interpretation: The DRAGON Score is a relatively easy to apply tool that is based information readily available at a patient’s initial presentation. The score predicts the functional outcome of stroke patients treated with IV-tPA. Despite statistically significant differences in baseline characteristics in this North American cohort compared to the derivation cohort, the DRAGON score model remains a reliable stratification tool with good predictive value.