Social competence showed no clear difference in marijuana use < 12 months Subjective compared with usual curricula (moderate certainty).
Combined programmes showed no clear difference in hard drug use < 12 months Subjective compared with usual curricula (high certainty).
Combined programmes showed no clear difference in hard drugs use ≥12 months Subjective compared with usual curricula (high certainty).
Combined programmes leads to lower any drugs use < 12 months Subjective compared with usual curricula (high certainty).
Social competence showed no clear difference in marijuana use ≥ 12 months Subjective compared with usual curricula (high certainty).
Social competence showed no clear difference in hard drug use < 12 months Subjective compared with usual curricula (moderate certainty).
Social competence probably leads to lower any drug use < 12 months Subjective compared with usual curricula (moderate certainty).
Social influence showed no clear difference in marijuana use < 12 months Subjective compared with usual curricula (moderate certainty).
Social influence showed no clear difference in marijuana use ≥ 12 months Subjective compared with usual curricula (moderate certainty).
Combined programmes showed no clear difference in marijuana use < 12 months Subjective compared with usual curricula (moderate certainty).
Combined programmes probably leads to lower marijuana use ≥12 months Subjective compared with usual curricula (moderate certainty).
Buprenorphine showed no clear difference in drop out Number of participants who did not complete the… compared with clonidine (moderate certainty).
Buprenorphine probably leads to higher initiation of naltrexone treatment Number of participants initiating… compared with clonidine (moderate certainty).
Buprenorphine detox may leads to higher drop out Number of participants who dropped out from the study compared with buprenorphine maintenance (low certainty).
Buprenorphine detox showed no clear difference in patients with positive urine at the end of treatment Number of… compared with buprenorphine maintenance (low certainty).
Buprenorphine detox may leads to higher self‐reported use at 12 months compared with buprenorphine maintenance (low certainty).
Buprenorphine detox showed no clear difference in enrolment in addiction treatment at 12 month compared with buprenorphine maintenance (low certainty).
Buprenorphine maintenance may leads to lower drop‐outs Number of participants who did not complete the study compared with buprenorphine detoxification (low certainty).