The odds ratio of being a smoker in intervention compared with control schools was 0.75 ( 95 % CI 0.55-1 .01 ) immediately after the intervention ( n = 9349 students ) , 0.77 ( 0.59-0 .99 ) at 1-year follow-up ( n = 9147 ) , and 0.85 ( 0.72-1 .01 ) at 2-year follow-up ( n = 8756 ) .
