Abstract: We identified 10 completed RCTs, most of which were relatively recent (2007 or later) and were conducted with at least some involvement from the intervention developer or the FAST organisation. Nine of the 10 trials were from the USA; the other was from the UK. Children were young (five to nine years old; mean age approximately six years), and therefore, whilst not so named in the reports, evaluations consisted of what is sometimes referred to as 'Kids FAST' and sometimes 'Elementary Level FAST'). Among the USA-based studies, at least 62% of participants were members of a racial/ethnic minority group (most commonly, African American or Latino). FAST was usually delivered in schools after the school day. Trials lasted about eight weeks and usually examined the effects of FAST relative to no additional intervention. Most studies were funded by agencies in the US federal government. We judged the certainty of evidence in the included studies to be moderate or low for the main review outcomes. Failure to include all families in outcome analyses (attrition) and possible bias in recruitment of families into the trials were the main limitations in the evidence. We included over 9000 children and their families in at least one meta-analysis. The follow results relate to meta-analyses of data at long-term follow-up. Primary outcomes Four studies (approximately 6276 children) assessed child school performance at long-term follow-up. The effect size was very small, and the CI did not include effects that, if real, suggest possibly important positive or negative effects if viewed from an individual perspective (SMD -0.02, 95% CI -0.11 to 0.08). We assessed the certainty of evidence for this outcome as moderate. No studies assessed child adverse events, parental substance use, or parental stress. Secondary outcomes Parent reports of child internalising behaviour (SMD -0.03, 95% CI -0.11 to 0.17; 4 RCTs, approximately 908 children; low-certainty evidence) and family relationships (SMD 0.08, 95% CI -0.03 to 0.19; 4 RCTs, approximately 2569 children; moderate-certainty evidence) also yielded CIs that did not include effects that, if real, suggest possibly important positive or negative effects. The CI for parent reports of child externalising behaviour, however, did include effects that, if real, were possibly large enough to be important (SMD -0.19, 95% CI -0.32 to -0.05; 4 RCTs, approximately 754 children; low-certainty evidence). Given these results, it is hard to support the assertion that assignment to FAST is associated with important positive outcomes for children and their parents.

Plain-language summary: We found 10 randomised controlled studies (studies where schools were assigned to receive FAST or to continue as usual, by a procedure similar to tossing a coin), with a total of more than 9000 children and their families. Nine of the studies took place in the USA and were funded by agencies in the US federal government. One study took place in the UK. Children's ages ranged from five to nine years, and most of the USA-based children were members of a racial or ethnic minority group. Boys and girls were represented at approximately equal rates. In most studies, FAST was delivered at children's schools after the end of the school day, although in some studies it was delivered outside of school (e.g. at a community centre). The trials lasted about eight weeks and usually examined the effects of FAST compared to no additional intervention. The evidence is current as of December 2018. A meta-analysis is a statistical method of combining data from several studies to reach a single, more robust conclusion. We were able to use data from nine studies in a meta-analysis measuring the impact of FAST for children aged between five and eight years. Although individual studies reported some positive findings, there was little evidence to suggest that being involved in a FAST programme results in important improvements in the primary outcomes of child school performance, parental substance abuse, or parental stress. No study measured child adverse outcomes. Furthermore, there was little evidence to suggest that FAST leads to important improvements in child behaviour or family relations. We judged the certainty of evidence in the included studies for the main review outcomes to be moderate or low risk. Failure to include all families in outcome analyses (attrition) and possible bias in recruitment of families into the trials were the main limitations in the evidence. Evidence on the effectiveness of being assigned to FAST is of moderate to low certainty and does not suggest that being assigned to FAST confers important benefits for students and their families.