Spoth R.L., Randall G.K., Trudeau L. et al.
Drug and Alcohol Dependence: 2008, 96(1–2), p, 57–68.
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Two of the most widely recommended US school and family prevention programmes retarded growth in some forms of substance use, especially among youngsters who had already used by their early teens, but there are some methodological concerns over the findings.
Summary 36 secondary schools in the rural US mid-west were randomly allocated to either carry on as normal (the 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. schools) or to one of two prevention programmes. Both were delivered primarily in the seventh grade (ages 12–13), and both featured the LifeSkills Training (LST) drug education curriculum consisting of fifteen classroom lessons with later 'boosters'. In one set of schools, these lessons were supplemented by the Strengthening Families Program: for Parents and Youth 10-14. This entails seven two-hour evening sessions plus four booster sessions in the following year, during which groups of about six or seven families focus in turn on particular parenting issues and skills. In the first hour of each session, parents and children learn in parallel; in the second, they come together to practice these skills with each other. Only a quarter of the families allocated to these (and 38% of those actively recruited) attended any of the family sessions, but results are reported for all the families offered the intervention, regardless of attendance.
Questionnaire responses from 1677 pupils surveyed about six months before the grade seven lessons formed the baseline to assess changes in substance use among the same pupils over each of the five years following the lessons. Typically by then aged 17–18, about three quarters of the starting sample responded to the final assessments. For the featured report the sample was narrowed down slightly to pupils who had provided the relevant outcome measures at least three times: at baseline; about a month after the seventh grade interventions; and during at least one follow-up. For these pupils, the analysis tested whether over the five and a half years:
• trends in the growth of substance use differed between the three sets of schools; and
• whether by the end levels of substance use also differed.
First the study assessed how many pupils had started to use alcohol, cigarettes or cannabis. Most consistently positive results were found for cigarettes; growth in the proportion who had tried smoking, and the final proportion who had used by age 17–18, were significantly lower in intervention schools compared to control schools. For cannabis, only the final proportion was significantly lower, and for alcohol, only the growth trend, and then only when the family intervention had supplemented the lessons. When these measures were combined in an index representing experience of all three substances, both the growth trend and the final outcomes favoured the interventions. Experience of getting drunk was also measured and, like drinking itself, only the growth trend favoured the interventions.
Similar analyses for current use on at least a monthly basis and other more serious patterns of substance use found no results favouring the interventions. However, there were such results among the fifth of pupils considered at high risk of developing substance use problems. These were the pupils who at the first survey point at age 12–13 had already used two of the three substances. Compared to their lower risk peers, among these pupils both interventions had consistently An exception was the frequency with which the pupils got drunk. There were also some significant growth trend differences, notably for the frequency of cannabis use and an index of monthly use of all three substances. greater effects on overall levels of use across the follow-up years. Further analysis showed that among lower risk pupils, the interventions made no significant difference. But among the higher risk fifth,growth in the average frequency of smoking cigarettes or using cannabis was less than in the control schools, and so too was final average frequency of use. This was not the case for the frequency of drinking or of getting drunk; for these measures only two Final frequency of use and of drunkenness after the LifeSkills curriculum without the family intervention supplement. of the eight outcomes significantly favoured the interventions. Among the same higher risk pupils, indices of serious use patterns combining measures of current or past use of all three substances Plus solvent misuse for one of the indices. consistently favoured the intervention schools.
Summarising their findings, the authors noted that for all substance initiation outcomes, one or both intervention groups showed significant, positive differences compared with the control group in the final follow-up year, and/or significant differences in growth trends over the five years since the interventions. In contrast, across all the pupils, more serious substance use outcomes reflecting mainly current and frequent use were not significantly affected. However, these forms of substance use were curbed when the analysis was restricted to higher risk pupils. Though the two interventions often bettered education-as-usual, in no case did one outperform the other. The authors speculated that less convincing initiation-prevention results than in earlier studies might have been due to the family intervention being delayed a year, when more pupils had already initiated substance use. In terms of affecting more serious forms of substance use, pupils already advanced in their substance use patterns responded relatively well, possibly because the messages were more 'real' for them and for their parents. Despite randomisation, there remained some significant baseline differences between control and intervention pupils which might also have obscured intervention impacts, though attempts were made to adjust for these in the analyses.
commentary The two programmes tested in the study enjoy among the most widely respected research records in substance use prevention (LST SFP). The featured study's strengths include large samples, reasonable follow-up rates, randomisation by school and an analysis controlling for the influence of the school itself, and outcome measures probing not just experience of the substances concerned, but how serious and lasting this was. Nevertheless the most which can be said is that the LifeSkills Training element probably retarded the initiation of smoking, possibly cannabis use, but not drinking, had no cross-sample benefits in respect of the forms of substance use of greatest concern, but may have had such benefits among the minority of pupils already relatively advanced in their substance use before the interventions started. Other LifeSkills Training studies have also most consistently found beneficial outcomes in respect of smoking, the programme's original target.
Focusing on the featured study's positive findings might give the impression of more all round success, but in respect of the full samples, these consisted of at most 13 out of 44 findings, and possibly (if arguably more appropriate methodological conventions had been followed) seven or fewer. Greater and more consistent success among the higher risk pupils is a tentative finding because of differences between intervention and control schools, because the study was not set up to test this subsample, and because of some methodological issues. Impacts on the forms of drug use of greatest concern emerged solely from this analysis, meaning that the interventions' ability to reduce these cannot be considered to have been demonstrated, though the possibility that this might prove to be the case is encouraging. Importantly, though many tests did not show the interventions were superior to education-as-usual, none Personal communication from Dr Spoth, July 2009. indicated that they were inferior; the only significant findings favoured the interventions. For more on all these issues see background notes.
Disappointingly, and despite earlier findings from the study, there was no real hint that adding the family programme improved on the school lessons in terms of the substance use measures reported in the study, though there may have been other benefits. Remaining support for the family programme comes mainly from a study whose findings (impressive as they were) derived from just over a third Though every family who participated and supplied the relevant data was included in the analysis regardless of whether they had attended the sessions. Also on all but one (parent education) of the variables measured (parent education, household income, target child gender, parent marital status, number of children, child conduct problems, and social-emotional distress), the families who participated in the study did not differ from those who did not. of the mainly white and rural families asked to participate in the study. A similar limitation applies to a later study of a substantially revised version among poor black families. Because of the way they were designed, these trials could establish benefits only among the minority of families prepared or able to participate in the interventions and complete the studies; they cannot be considered a secure indication of how the interventions would perform if applied across the board. So far in the UK a small pilot study has established the programme's feasibility among a small set of families.
This leaves two of the most thoroughly researched universal prevention programmes for children of secondary school age with mixed findings of uncertain relevance to how they might perform if truly applied across the board. At least part of the problem lies in not in whether the benefits of these programmes are (or at least, can be) real, but in the difficulty of showing they are real. Verdicts in respect of drinking that public health strategies built on education and persuasion are relatively ineffective compared to measures such as restricting availability and raising price, would not be altered by the featured study. For smoking, the case for education in schools as a public health strategy is considerably stronger. Universal prevention programmes in general, and school-based programmes in particular, have greater impacts on tobacco use than on use of the other two substances featured in the study.
Some evidence supports the modest effectiveness of school programmes in preventing cannabis use. But of the four studies on which this verdict was based, one was a primary school programme not focused on substance use at all but on classroom management, education and parenting, another was conducted only among pupils for some reason excluded from mainstream education, and the programme studied in a third has since failed in a more real-world study conducted by researchers not associated with its development. The remaining study was conducted in secondary schools and concerned LifeSkills Training, but the impact on cannabis use was not statistically significant. This line up does not offer much support to drug education in mainstream secondary schools as a means of preventing cannabis use.
Mixed findings of a prevention impact from school programmes targeting substance use do not negate the possibility that general attempts to create schools conducive to healthy development will affect substance use along with other behaviours, nor do they relieve schools of the obligation to educate their pupils on this important aspect of our society. As much as the limited research, such considerations led the UK's National Institute for Health and Clinical Excellence (NICE) to recommend that alcohol education should be an integral part of national science and health education curricula, in line with government guidance.
Thanks for their comments on this entry in draft to Richard Spoth of Iowa State University, Andrew Brown of the Drug Education Forum and David Foxcroft of Oxford Brookes University. Commentators bear no responsibility for the text including the interpretations and any remaining errors.
Last revised 02 July 2009. First uploaded
STUDY 2003 Family programme improves on school lessons
STUDY 2000 Education's uncertain saviour
REVIEW 2015 Prevention of addictive behaviours