This page refers to the current evidence on the effectiveness of the available prevention interventions for communities. Information on the methodology used and the definition of terms can be found on the methodology page.
Date of last update: 11.05.2012. Next update: March 2013.
Summary: Comprehensive community based programmes are more effective than interventions targeting community or school only in reducing licit and illicit drug use among high risk young individuals. Multicomponent and interactive programs are effective in reducing licit drug use.
Comprehensive approaches involving community, school and family were found effective in a systematic review of 222 studies (14 systematic reviews; 103 RCTs; 52 Controlled non-randomized studies; 18 CBA; 35 BA) (Jones et al., 2006) at preventing/delaying/reducing:
There was no difference in effectiveness between ‘school-community’ programmes and ‘community-only’ programmes. Moreover, low risk population effect sizes were significantly greater across all types of interventions (‘comprehensive’, ‘school-community’, ‘community-only’) for tobacco (SMD = 0.05, SMD = 0.13); and cannabis (SMD = 0.04, SMD = 0.10). No other significant differences were reported.
Mentoring (intended as a supportive relationship in which one person offers support, guidance and concrete assistance to the partner, based on the sharing of experience and expertise without expectation of personal gain by the mentor - Center for Substance Abuse Prevention 2000) was found in a systematic review (Thomas et al., 2011) more effective than no interventions in:
Coordinated, widespread, multi-component community interventions include age restrictions on tobacco purchase, programs for prevention of disease (like heart disease), mass media and school programs. Such interventions were found in a systematic review of 17 studies (Sowden and Stead, 2003) to:
Programmes offering strong behavioural life skills development content, emphasised team-building, interpersonal communication methods, and introspective learning approaches focusing on self-reflection were found to be effective in a review of studies (Springer et al., 2004) in:
These programmes were based upon a clearly articulated and coherent programme theory, and provided quality contact with young people.
No interventions met the criteria for this category.
Anti-alcohol/cannabis community interventions were analyzed in a review of 29 reviews (McGrath et al., 2006) and weak studies due to lack of control groups suggested a reduction in:
No pooled analysis could be done on mentoring (understood here to mean a supportive relationship in which one person offers support, guidance and concrete assistance to the partner, based on the sharing of experience and expertise without expectation of personal gain by the mentor — Center for Substance Abuse Prevention 2000) in a systematic review (Thomas et al., 2011) for:
There is little evidence that interventions with multiple components are more effective than interventions with single components as shown in a systematic review (Foxcroft et al., 2011):
No interventions met the criteria for this category.
Below you can find definitions and further explanation for some of the terms used in this section of the Best practice portal. A more general glossary for the best practice portal is also available.
A type of prevention intervention which aims to they aim to modify inner qualities (personality traits such as self-esteem and self-efficacy, and motivational aspects such as the intention to use drugs).
Before-after (BA) study design
Interventions for which precise measures of the effects in favour of the type of intervention were found in systematic reviews of relevant studies. An intervention ranked as ‘beneficial’ is suitable for most patients/contexts. See the relevant module methodology page for further information.
Controlled before-after (CBA) study design. UCBA stands for Uncontrolled before-after study design.
Cognitive behavioral therapy is an individual based intervention occurring in three stages. Phase 1 is aimed at determining and prioritizing the patient’s problems and constructing the treatment contract. Phase 2 is aimed at increasing coping competence and reducing risky behaviors. Phase 3 focuses on relapse prevention. Each session is administered once per week over a period of 4-6 months with 60- to 90-minute sessions (Beck AT, Wright FW, Newman CF, Liese B. Cognitive Therapy of substance abuse. New York: Guilford Press, 1993).
Controlled clinical trials (CCT)
A cohort study is a type of observational study that follows a group of people (i.e. a cohort) over time. In a prospective cohort study, the cohort is formed and then followed over time. In a retrospective cohort study, data is gathered for a cohort that was formed sometime in the past.
The Confidence Interval (CI) is a measure of the precision (or uncertainty) of study results. It is the interval that most likely includes the true value of the parameter we are calculating, where 'most likely' is taken by common usage to be a 95% probability. Thus the current expression of '95 % CI'. A wide CI indicates less precise estimates of effect and vice versa.
Current population survey (CPS)
A cross-sectional study is a study employing a single point of data collection for each participant or system being studied.They are usually conducted to estimate the prevalence of the outcome of interest for a given population at a given point in time.
Interventions that gave negative results if compared with a standard intervention or no intervention, for example. See the relevant module methodology page for further information.
Additional information for prevention
For ethical reasons this category in prevention should be considered as interventions with negative and undesired (iatrogenic) effect.
Individual psychotherapy is a standard individual treatment based on counseling and motivational interviewing and focused on substance use triggers and strategies for relapse prevention. It includes elements of cognitive-behavioral therapy (CBT).
Intermittent time series design (CPS)
Knowledge-focused prevention intervention
A type of prevention intervention which aims to to enhance knowledge of drugs, and drug effects, and consequences.
Interventions that were shown to have limited measures of effect, that are likely to be effective but for which evidence is limited. An intervention ranked as ‘likely to be beneficial’ is suitable for most contexts/patients, with some discretion. See the relevant module methodology page for further information.
The Number Needed to Treat (NNT)indicates the number of patients that needs to be treated to obtain one respondent patient. Numerically the NNT is the reciprocal of the difference between the proportion of events in the experimental and the comparison group (absolute risk reduction). Taking into consideration that the ideal NNT would be 1 (the unreal situation in which every single patient succeeded) it is easily understood that a NNT value close to 3 or 4 would be very good.
The Adjusted Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups, yet they are calculated adjusting for or controlling for other possible contributions from other variables (tipically demographic variables) in the model. An AOR equal to 1 implies that the the event is equally probable in both groups. An AOR greater than 1 implies that the event is more likely in the first group. An AOR less than 1 implies that the event is less likely in the first group.
The Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups. Like the Relative Risk, an OR equal to 1 implies that the the event is equally probable in both groups. A OR greater than 1 implies that the event is more likely in the first group. A OR less than 1 implies that the event is less likely in the first group. In medical research, the odds ratio is commonly used for case-control studies, as odds, but not probabilities, are usually estimated. Relative risk is used in randomized controlled trials and cohort studies.
A p-value is a measure of how much evidence we have against the null hypothesis. The null hypothesis represents the hypothesis of no change or no effect. The smaller the p-value, the more evidence we have against the null hypothesis thus it is more likely that our sample result is true. Traditionally, researchers will reject a null hypothesis if the p-value is less than 0.05.
Randomised controlled trial (RCT)
The Relative Risk (RR) is used to compare the risk in the two different groups of people, i.e. treated and control groups to see if belonging to one group or another increases or decreases the risk of developing certain outcomes. This measure of effect will tell us the number of times an outcome is more likely (RR > 1) or less likely (RR < 1) to happen in the treatment group compared with the control group.
Interventions that obtained measures of effects in favour of the intervention, but that showed some limitations or unintended effects that need to be assessed before providing them. See the relevant module methodology page for further information.
Interventions for which there are not enough studies or where available studies are of low quality (with few patients or with uncertain methodological rigour), making it difficult to assess if they are effective or not. Interventions for which more research should be undertaken are also grouped in this category.
Additional information for prevention
For prevention interventions, this is also known as 'zero effect'.
A type of prevention intervention which aims to enhance students’ abilities in generic skills, refusal skills and safety skills.
The Standardised Mean Difference (SMD) is the difference in means divided by a standard deviation. Note that it is not the standard error of the difference in means (a common confusion). The standardized mean difference has the important property that its value does not depend on the measurement scale. It may be useful if there are several trials assessing the same outcome, but using different scales.
The z-score (aka, a standard score) indicates how many standard deviations an element is from the mean of the population.
Though there is no single definition for the term 'community', as used here it is understood to mean a group of individuals sharing a common geographical and administrative setting. Interventions within a community do not necessarily address all members of that community but possibly only a specific part, i.e. those at higher risk of substance use (aka vulnerable groups). In cases where the term 'community' is being used in a different sense, this is indicated.
As for the module on school interventions, being the community a wide concept including many different people and their relations, no specific risks exist in being member of a community. Community based interventions are rather developed with the aim of involving different social structures and actors into comprehensive approaches.
Interventions included in this section involve all individuals or specific vulnerable groups in the community and aim to hinder or limit the use of substances.
Also interventions with family- or school-based components were included in this section, provided the community-based component was predominant.
The main aim of prevention interventions provided to communities is to deter or to delay the onset of substance use/abuse by providing all individuals with the information and skills necessary to prevent the problem.