To investigate the association between EVT start time in acute ischemic stroke (AIS) and mid-term functional outcome.
This retrospective cohort study included all AIS cases treated with EVT from two stroke center registries from January 2012 to December 2018. The primary outcome was the score on the modified Rankin Scale (mRS) and the utility-weighted mRS (uw-mRS) at 90 days. A proportional odds model was used to calculate the common odds ratio as a measure of the likelihood that the intervention at a given EVT start time would lead to lower scores on the mRS (shift analysis).
One thousand five hundred fifty-eight cases were equally allotted into twelve EVT-start-time periods. The primary outcome favored EVT start times in the morning at 08:00-10:20 and 10:20-11:34 (common odds ratio (OR), 0.53; 95% confidence interval (CI), 0.38 to 0.75; P<0.001; OR, 0.62; 95% CI, 0.44 to 0.87; P=0.006, respectively), while it disfavored EVT start times at the end of the working day at 15:55-17:15 and 18:55-20:55 (OR, 1.47; 95% CI, 1.03 to 2.09; P=0.034; OR, 1.49; 95% CI, 1.03 to 2.15; P=0.033). Symptom onset-to-EVT start time was significantly higher and use of IV t-PA significantly lower between 10:20-11:34 (P<0.004 and P=0.012, respectively).
EVT for AIS in the morning leads to better mid-term functional outcome, while EVT at the end of the work day leads to poorer mid-term functional outcome. Neither difference in baseline factors, standard workflow and technical efficacy metrics could be identified as potential mediators of this effect.