Table 1.

Characteristics of included studies

Study ID	Setting and Country	Type of Intervention	Gender breakdown (%)	Age (Mean, SD)
1. Grenard et al., 2007 [27]	Alternative high school campuses, Los Angeles, USA	Individual Motivational Interviewing (1 session of 25 minutes)	67% Male, 33% Female	16.1 (0.9)
2. Friedman et al., 2002 [28]	Residential Facility for court adjudicated adolescent males, Philadelphia, USA	Botvin Life Skills Training (20 sessions), Prothrow/Stith Anti-Violence model (20 sessions), Values Clarification procedure-20 sessions: (55 minutes each)	100% Male	15.5 (1.1)
3. Stein et al., 2006 [29]	Northwest juvenile correctional facility, USA	Motivational Interviewing (60 minute , 90 minute booster)	89.5% Male, 10.5% Female	17.09 (1.06)
4. Bailey et al., 2004 [33]	Youth Centre, New South Wales, Australia	Brief Motivational Interviewing group intervention (4 sessions-first session 40 minutes, remaining sessions 30 minutes)	50% Male, 50% Female	15.44 (1.80)
5. Peterson et al., 2006 [34]	Homeless adolescents-drop in centres, street intercepts. Seattle, Washington, USA	Brief Motivational Enhancement (1 session of approximately 30 minutes)	54.7% Male, 45.3 Female	17.4 (1.54)
6. Winters et al., in press [26]	Urban Public High School, Minnesota, USA	Teen Intervene-Brief Motivational Interviewing (2 sessions with adolescent of 60 minutes, 1 session of 60 minutes with parent)	51.5% Male, 48.5% Female	16.1 (n/a)
7. Walton et al., 2010 [31]	Emergency Department, Michigan, USA	SafERteens therapist vs computer brief intervention (1 session of 35 minutes)	43.5% Male, 56.5% Female	16.8 (1.3)
8. Spirito et al. , 2004 [30]	Northeast Emergency Department, USA	Brief Motivational Interviewing (1 session of 35–45 minutes)	63.8% Male, 36.2% Female	15.6 (1.2)
9. D’Amico et al., 2008 [32]	Community-based health clinic, Los Angeles, USA	Project CHAT: Motivational Interviewing (1 session of 15–20 minutes; 5–10 minute booster telephone call	47.6% Male, 52.4% Female	16.0 (1.85)