Cumulative probabilities of this outcome were 11.0 % ( 95 % confidence interval , 7.9-15 .2 ) versus 6.3 % ( 4.0-9 .8 ) in the endarterectomy group at the 5-year follow-up ( hazard ratio , 1.85 ; 1.00-3 .40 ; P = 0.04 ) and 11.5 % ( 8.2-15 .9 ) versus 7.6 % ( 4.9-11 .8 ; hazard ratio , 1.70 ; 0.95-3 .06 ; P = 0.07 ) at the 10-year follow-up .