Independent risk factors modifying the risk of CNP were cardiac failure ( risk ratio [ RR ] 2.66 , 95 % CI 1.11 to 6.40 ) , female sex ( RR 1.80 , 95 % CI 1.02 to 3.20 ) , the degree of contralateral carotid stenosis , and time from randomization to treatment > 14 days ( RR 3.33 , 95 % CI 1.05 to 10.57 ) .