This study examined substance use outcomes when community-based teams implement evidence-based family and school interventions. Analyses of effects showed evidence of intervention-control differences on a range of substance initiation and current use measures. Three features of the interventions producing these results are noteworthy. First, the design of these interventions followed research-based principles and met criteria for evidence of efficacy, suggested by current literature.36
Second, the community teams were required to choose a combination of one family-focused and one school-based intervention from a menu of evidence-based interventions. With this combination of interventions, a range of empirically-supported family-, school-, and peer-related etiological factors for substance use were addressed.9
Third, the interventions were implemented under “real world” conditions, consistent with an effectiveness trial.15
A critical element of this model is the provision of regular and proactive technical assistance for the community team implementation through the land grant university based Cooperative Extension System. The use of this system and active technical assistance are key features of the PROSPER model that is intended for future dissemination to other communities.21,22
The range of substances on which positive effects were observed also is noteworthy. The interventions were designed to impact substance use by intervening with etiological risk and protective factors that were expected to influence substance use generally, independent of the specific type of substance in question. Thus, intervention content was not substance specific. Nonetheless, there were statistically significant effects on a broad range of substances, from frequently used gateway substances to substances used at lower rates in the general population, like methamphetamines, inhalants, and ecstasy.
Concerning the practical significance of effects, the relative reduction rates for marijuana, methamphetamine, and ecstasy initiation are especially noteworthy. For example, the initiation rate of marijuana use was 40% lower in the intervention group than among controls. This suggests that for every 100 non-intervention, general population adolescents who begin using marijuana, only 60 intervention group adolescents would do so over the same period. In addition, effect sizes were primarily in the moderate range when calculated at the community-level, as is most consistent with the intent-to-treat analytic design and most directly relevant to the assessment of community-level public health impact.
The real world conditions under which the present effectiveness trial was conducted also are important in interpreting the practical significance of the results. Showing positive results under such conditions can be expected to be particularly difficult when conducting a rigorous assessment of community-level outcomes using intent-to-treat analysis. Under these conditions, the lower degree of researcher control over such factors as program recruitment could easily lead to weaker community-level effects. Nonetheless, in the current study, with intervention implementation driven by the local teams, intervention participation (17% of the general population families targeted, in the case of the family-focused intervention) and program fidelity were sufficiently high to produce significant reductions in adolescent substance use. In other words, these results are of greater relevance for typical community-based prevention practice than results from an efficacy trial conducted under artificially well-controlled circumstances. A number of barriers to widespread dissemination concern resource demands for sustained quality implementation of evidence-based preventive interventions, including the requisite human and financial capacity for this type of implementation. For example, implementing the SFP 10–14 for a group of 8–10 families costs approximately $3,000. The per group costs may be higher or lower, depending upon the hourly wage rate for staff, the level of participation incentives used, and what elements of the program were donated (for example, food). The PROSPER partnership model is designed to address the costs of SFP 10–14 implementation and other resource issues in two ways. First, sustainability training is central to the PROSPER model. This sustainability training is substantial, starts early on, and focuses on sustaining both effective community team functioning over time and quality program implementation, including training in local fundraising. As of this writing, all community-teams have continued to operate and each has garnered sustainability funding to continue both the family and school programs in their communities.
Second, PROSPER addressed human resource barriers to sustainability through its design as a hybrid of other types of community-based programming models, a hybrid that is grounded in a stable human resource system. As described in an earlier report20
, one type of model involves no university-based research staff and another model entails paid research staff that are directly and extensively involved. The PROSPER model consists of community-based implementation by a local community team, consisting mostly of local community volunteers who have primary responsibility for implementation. As described earlier, support for community team implementation efforts is provided by technical assistants with prevention programming expertise. This technical assistance is based in a stable system (the Land Grant University Cooperative Extension System) that provides resources extending beyond research grant funding. Thereby, the PROSPER model addresses both financial and human resource barriers to widespread implementation.
Unlike the authors’ prior prevention trials, there were no effects on alcohol initiation. Earlier studies have suggested that effects on alcohol initiation are observed primarily when the intervention is implemented sufficiently early in the phase during which young adolescents are experimenting with use.43, 44
Unfortunately, in PROSPER the base rates of alcohol initiation in 6th
grade were higher than expected and may have suppressed the intervention effect on that outcome. Indeed, most of the significant initiation effects were observed for substances with lower base rates. Notably, on the one alcohol intervention outcome with a relatively lower base rate (drunkenness) relatively more positive results were observed.
Consistent with earlier reports, we found comparable intervention effects among lower-and higher-risk subsamples or, in some cases, stronger effects for higher-risk youth.18,19
This pattern of findings across studies is important in that it counters the common speculation that universal interventions often benefit only those in the general population at lower risk.10
The present findings highlight how universal strategies can provide an avenue for reaching at least some higher-risk youth, while avoiding iatrogenic effects sometimes observed when high-risk youth are grouped together for intervention.45
Most importantly, results indicating comparable or stronger benefits for higher-risk youth show how a community-based approach like the one tested can address the needs of that segment of the community youth population.
The reader should be cognizant of several limitations of the current study. First, although it was conducted in two states and included diverse communities with a range of populations, the largest community was approximately 44,500 in population (with the smallest being approximately 7,000) and the participants were primarily Caucasian. It is not entirely clear to what extent the PROSPER model results would generalize to students in larger metropolitan areas and non-white populations; further research with such populations will be required to assess generalizability of the findings. Second, all of the substance use measures are based on self-report; this could introduce some bias into the reporting, although there is support in the literature for the validity of this type of data.38–40,46
Addressing the health and economic consequences of adolescent substance use noted in the introduction requires diffusion of effective community-based, empirically-supported interventions; community-based partnership approaches have been highly recommended for this purpose.17,22,47,48
The significant differences in levels of substance use across several different measures for the intervention group as compared with a control group—differences that past research17,36
suggests will increase over time—are especially noteworthy in light of this recommendation for community-university partnerships.22,47
Thus, the findings suggest that the PROSPER partnership model for sustained quality implementation of evidence-based interventions by communities has public health potential and warrants further research.