Mean ASI Drug Use composite score at baseline was 0.11 ( SD , 0.10 ) ( brief intervention ) and 0.11 ( SD , 0.10 ) ( enhanced care as usual ) and at 3 months was 0.10 ( SD , 0.09 ) ( brief intervention ) and 0.09 ( SD , 0.09 ) ( enhanced care as usual ) and not significantly different ( difference in differences , = 0.008 [ 95 % CI , -0.006 to 0.021 ] ) .