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Foxcroft D.R., Tsertsvadze A.
Cochrane Database of Systematic Reviews: 2011, 5, Art. No.: CD009113.
This authoritative review says that school programmes which work best at preventing youth drinking problems are not specifically about alcohol at all, but instead target problem behaviour more generally.
Summary This review updates a more wide ranging review of alcohol prevention published in 2002 but focuses on school-based programmes. It searched for studies published up to mid-2010 which addressed all the relevant grades or ages in the school population (hence 'universal') rather than selecting pupils based on their risk levels or actual drinking. The aim was to find trials which randomly assigned pupils (whether individually, as classes, schools or some other 'unit of analysis') to a psychosocial intervention expected to affect drinking versus an alternative school and/or non-school-based programme, or just the standard curriculum. The intervention might be targeted specifically at drinking, or a more generic programme intended to affect this among other outcomes such as healthy and pro-social lifestyles.
The analysts found 53 such studies of which 41 were conducted in the USA and none in the UK. Most (39) tested a generic intervention intended to affect drinking along with other non-substance use behaviours. In 85% of studies the focal intervention was compared to a standard curriculum. It was considered inappropriate to pool the results from the 53 trials because they differed too much in the types of population sampled, the nature of the interventions, and in their measures of drinking outcomes.
Of the 11 trials of alcohol-specific interventions, five found no statistically significant impacts relative to a standard curriculum and six found some differences which were statistically significant. However, in most of these six studies significant impacts were confined to certain subgroups such as pupils who had (or had not) already drunk alcohol or girls rather than boys, and in some not all drinking measures were significantly affected.
Another 39 studies tested more generic programmes. Of these, 24 found no statistically significant impacts on drinking relative to a standard curriculum or to a no-intervention control A group of people, households, organisations, communities or other units who do not participate in the intervention(s) being evaluated. Instead, they receive no intervention or none relevant to the outcomes being assessed, carry on as usual, or receive an alternative intervention (for the latter the term comparison group may be preferable). Outcome measures taken from the controls form the benchmark against which changes in the intervention group(s) are compared to determine whether the intervention had an impact and whether this is statistically significant. Comparability between control and intervention groups is essential. Normally this is best achieved by randomly allocating research participants to the different groups. Alternatives include sequentially selecting participants for one then the other group(s), or deliberately selecting similar set of participants for each group. group and one found a negative impact. The remaining 14 studies found some statistically significant reductions in drink-related outcomes relative to a standard curriculum, though in three these were confined to certain subgroups of pupils, and some drinking measures were not significantly affected.
In terms of identified programmes, it was noted that in all the relevant studies the Life Skills Training social and personal skills curriculum yielded positive results, as in two of three trials did the early years classroom management strategy known as the Good Behaviour Game. Also with a relatively good record was the Unplugged European drug education curriculum. In contrast, there were no statistically significant positive effects in trials which evaluated the Project ALERT substance use prevention curriculum or Drug Abuse Resistance Education (DARE) classes typically delivered by police officers.
One interpretation of the overall picture – some studies showing some effects and others none – is that school-based alcohol prevention does not work, and that such statistically significant impacts as there are arise purely by chance. However, this seems unlikely given the proportion and sample size of studies which found statistically significant effects, coupled with the likelihood that many studies were too small for relatively modest effects to register as statistically significant. More likely is that some school-based psychosocial and developmental prevention interventions truly are effective in particular settings for reducing alcohol misuse among young people, while others are not. What accounts for this difference is unclear, hampering the effort to translate the findings in to specific recommendations for practice.
Overall, the evidence is more convincing for certain generic rather than alcohol-specific programmes. Among the generic programmes, those based on psychosocial or developmental approaches (life skills in Life Skills Training; social skills and norms in Unplugged; behaviour norms and peer affiliation in the Good Behaviour Game) were most likely to report statistically significant effects over several years (in the case of the Good Behaviour Game, up to 12 years) when compared to standard school curricula or other types of interventions. The impacts were small but, across a population, potentially important. Generic programmes offer the additional advantage of potentially impacting on a broader set of problem behaviours, for example antisocial behaviour or the use of cannabis, tobacco, or harder drugs. Such programmes could be considered as policy and practice options, though variability in outcomes means their effectiveness should be tested in different settings.
Certain common methodological shortcomings limit confidence in the findings. Caution should be exercised in accepting statistically significant findings among certain subgroups, Post-hoc subsample analyses are best seen as generating hypotheses for testing in a study specially designed for this purpose. The main problems are that they rob the results of the reassurance of the level playing field created by randomising patients to different treatments, they build on what may be chance variation in the effectiveness of the intervention between different subsamples, test effects not derived from the theory of how the intervention is supposed to work, and (there is no implication that this was a problem in this case) can capitalise on the fact that samples can be sub-sampled in any number of ways until one (perhaps purely by chance) results in a significant finding. As a result, "any conclusion of treatment efficacy (or lack thereof ) or safety based solely on exploratory subgroup analyses are unlikely to be accepted" (Lewis J.A. "Statistical principles for clinical trials (ICH E9): an introductory note on an international guideline." Statistics in Medicine: 1999, 18, p. 1903–1904. http://www3.interscience.wiley.com/journal/63000985/abstract?CRETRY=1&SRETRY=0. These risks are eliminated or reduced by specifying the subsamples in advance at the time the trial is designed but often this is not the case (Al-Marzouki S., Roberts I. "Selective reporting in clinical trials: analysis of trial protocols accepted by The Lancet." The Lancet: 2008, 372, 19 July, p. 201). especially if these arise from tests not planned in advance. Poor follow-up rates remain a challenge. Beyond the first follow-up, few studies met the 80% standard expected of good trials, yet few used more advanced statistical techniques to adjust for these shortfalls.
commentary Not specifically in relation to drinking but substance use in general, Findings has also highlighted the effectiveness of generic prevention programmes. Some do not mention substance use at all, but instead target parenting or school affiliation and classroom management techniques which affect vulnerability to developmental problems. UK national policy is also leaning in this direction. Breaking with previous versions, the 2010 English national drug strategy and also public health plans have focused attention on early years parenting, particularly in vulnerable families. Though it was unable to statistically establish their superiority, its conclusions had to be hedged due to methodological concerns, and there remained a mystery over why some programmes worked and others did not, the featured review offers authoritative backing to this policy trend. It remains the case however that in respect of preventing harmful drinking, no type of psychosocial intervention has attracted as much scientific support as population-wide changes like price rises and outlet restrictions which affect everyone, independent of the choices they make.
Thanks for their comments on this entry in draft to David Foxcroft of Oxford Brookes University in England. Commentators bear no responsibility for the text including the interpretations and any remaining errors.
Last revised 30 September 2011
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