Biochemically validated 7-day tobacco abstinence at 6 months was higher with sustained care ( 26 % ) than with standard care ( 15 % ) ( relative risk [ RR ] , 1.71 [ 95 % CI , 1.14-2 .56 ] , P = .009 ; number needed to treat , 9.4 [ 95 % CI , 5.4-35 .5 ] ) .