School-based prevention for illicit drugs' use.

BACKGROUND: Drug addiction is a chronic, relapsing disease. Primary interventions should be aimed to reduce first use, or prevent the transition from experimental use to addiction. School is the appropriate setting for preventive interventions.

OBJECTIVES: To evaluate the effectiveness of school-based interventions in improving knowledge, developing skills, promoting change, and preventing or reducing drug use versus usual curricular activities or a different school-based intervention .

SEARCH STRATEGY: MEDLINE , EMBASE, ERIC, PSYCHINFO, Cochrane Library, ACP Journal Club, Cochrane Drug and Alcohol Group Register, updated to February 2004, were searched. Bibliography of papers was checked and personal contacts were made to identify other relevant studies.

SELECTION CRITERIA: RCTs, CCTs or Controlled Prospective Studies (CPS) evaluating school-based interventions designed to prevent substance use.

DATA COLLECTION AND ANALYSIS: Data were selected and extracted independently by two reviewers. Quality was assessed with the CDAG checklist. Interventions were classified as skills, affective, knowledge-focused and other characteristics were also studied (teaching, follow-up implementation, context activation).

MAIN RESULTS: 32 studies (29 RCTs and 3 CPSs) were included. 28 were conducted in the USA; most were focused on 6th-7th grade students, and based on post-test assessment. RCTs: (1) Knowledge vs usual curricula: Knowledge focused programs improve drug knowledge (SMD=0.91; 95% CI: 0.42, 1.39).(2) Skills vs usual curricula: Skills based interventions increase drug knowledge (WMD=2.60; 95% CI: 1.17-4.03), decision making skills (SMD=0.78; CI95%: 0.46-1.09), self-esteem (SMD=0.22; CI95%: 0.03-0.40), peer pressure resistance (RR=2.05; CI95%: 1.24-3.42), drug use (RR=0.81; CI95%: 0.64, 1.02), marijuana use (RR=0.82; CI95%: 0.73, 0.92) and hard drug use (RR=0.45; CI95%: 0.24-0.85). (3) Skills vs knowledge: No differences are evident.(4) Skills vs affective: Skills-based interventions are only better than affective ones in self-efficacy (WMD=1.90; CI95%: 0.25, 3.55). (5) Affective vs usual curricula: Affective interventions improve drug knowledge (SMD=1.88; CI95%: 1.27, 2.50) and decision making skills (SMD=1.35; CI95%: 0.79, 1.9). (6) Affective vs knowledge: Affective interventions improve drug knowledge (SMD=0.60; CI95%: 0.18,1.03), and decision making skills (SMD=1.22; CI95%: 0.33, 2.12). Results from CPSs: No statistically significant results emerge from CPSs.

AUTHORS' CONCLUSIONS: Skills based programs appear to be effective in deterring early-stage drug use. The replication of results with well designed, long term randomised trials, and the evaluation of single components of intervention (peer, parents, booster sessions) are the priorities for research. All new studies should control for cluster effect.