The differences between groups were also nonsignificant after we restricted the analysis to patients who reported excessive substance use at baseline ( OR 1.6 , 95 % CI 0.9-2 .8 , at 3 mo ; OR 1.7 , 95 % CI 0.9-3 .2 , at 6 mo ; and OR 1.9 , 95 % CI 0.9-4 .0 , at 12 mo ) .