A widely accepted metric (telephone assessment of the modified Rankin scale score at 90 days) may not accurately reflect the real-life outcome of endovascular stroke treatment

Introduction: The modified Rankin Score (mRS) collected at approximately 90 days after stroke onset is a reliable and reproducible measure of stroke outcome. It was utilized in the randomized controlled trials that established the safety and efficacy of endovascular stroke treatment. It has been incorporated as a core metric for measuring quality of care in comprehensive stroke centers. We aimed to evaluate the value of the 90-day mRS considering that a certain percentage of patients may fail to respond to coordinator phone calls. Methods: We retrospectively analyzed patients who received endovascular stroke treatment in a comprehensive stroke center from January 2015 to March 2017, and who were prospectively enrolled in the Get With The Guidelines-Stroke Registry. We calculated the response rates to coordinator phone calls at approximately 90 days from stroke onset. Several calls were placed according to the established institutional policy. We compared the response rates of patients who had successful or unsuccessful recanalization, as reported by the endovascular specialist at the time of the procedure. Results: We identified 79 patients who received endovascular treatment, and who were contacted by the coordinators at approximately 90 days after stroke onset. 58 patients had successful recanalization (as defined by reported TICI grades IIb and III), whereas 21 patients had unsuccessful recanalization (as defined by reported TICI grades O, I, and IIa). 44/58 patients with successful recanalization responded to coordinator calls, compared to 11/21 patients with unsuccessful recanalization. The difference in proportions was statistically significant (p=0.045). Conclusions: Patients who have unsuccessful recanalization after endovascular stroke treatment are significantly less likely to respond to coordinator calls. Therefore, their mRS cannot be estimated, and the long-term outcome of the endovascular procedure cannot be assessed. Since these patients are more likely to have died, or be in a supervised facility (and therefore not accessible at their previous phone number), the telephone assessment of the mRS is likely not an accurate measure for the long-term therapeutic effect of endovascular stroke treatment