Seventy-eight percent of patients in the buprenorphine group ( 89 of 114 [ 95 % CI , 70 % -85 % ] ) vs 37 % in the referral group ( 38 of 102 [ 95 % CI , 28 % -47 % ] ) and 45 % in the brief intervention group ( 50 of 111 [ 95 % CI , 36 % -54 % ] ) were engaged in addiction treatment on the 30th day after randomization ( P < .001 ) .