Effectiveness of the strengthening families programme 10-14 in Poland: cluster randomized controlled trial.

: The Strengthening Families Programme for youth aged 10-14 and parents/carers (SFP10-14) is a family-based prevention intervention with positive results in trials in the United States. We assessed the effectiveness of SFP10-14 for preventing substance misuse in Poland. : Cluster randomized controlled trial with 20 communities (511 families; 614 young people) were allocated to SFP10-14 or a control arms. Primary outcomes were alcohol, smoking and other drug use. Secondary outcomes included parenting practices, parent-child relations, and child problem behaviour. Interview-based questionnaires were administered at baseline and at 12- and 24-months post-baseline, with respective 70.4 and 54.4%, follow-up rates. : In Bayesian regression models with complete case data we found no effects of SFP10-14 for any of the primary or secondary outcomes at either follow-up. For example at 24-months, posterior odds ratios and 95% credible intervals for past year alcohol use, past month binge drinking, past year smoking, and past year other drug use, were 0.83 (0.44-1.56), 0.83 (0.27-2.65), 1.94 (0.76-5.38) and 0.74 (0.15-3.58), respectively. Although moderate to high attrition rates, together with some evidence of systematic attrition bias according to parent education and family disposable income, could have biased the results, the results were supported in further analyses with propensity score matched data and 40 multiple imputed datasets. : We found no evidence for the effectiveness of SFP10-14 on the prevention of alcohol or tobacco use, parenting behaviour, parent-child relations or child problem behaviour at 12- or 24-month follow-up in a large cluster randomized controlled trial in Poland.