Endovascular therapy , initiated at a median of 210 minutes after the onset of stroke , increased early neurologic improvement at 3 days ( 80 % vs. 37 % , P = 0.002 ) and improved the functional outcome at 90 days , with more patients achieving functional independence ( score of 0 to 2 on the modified Rankin scale , 71 % vs. 40 % ; P = 0.01 ) .