Best practice portal:
Prevention interventions for families

This page refers to the current evidence on the effectiveness of the available prevention interventions for families. Information on the methodology used and the definition of terms can be found on the methodology page.

Date of last update: 30.6.2011.     Next update: February 2012.

Available evidence for prevention interventions for families

Summary: Comprehensive family-oriented prevention interventions proved to be effective in reducing substance use (licit and illicit). Home visitation for disadvantaged families showed effects in reducing licit substance use. Interventions aimed at parents only needs to be further investigated.

Beneficial

No interventions met the criteria for this category.

Likely to be beneficial

Comprehensive family-oriented prevention for cannabis use

Comprehensive family-oriented prevention, which includes training for parents, children and whole families, was found to be effective in  one study included in a systematic review of  9 cluster randomised studies and 8 randomised studies (N = 1230) (Gates et al., 2006) — although with some disagreement and methodological weaknesses — in:

• reducing lifetime cannabis use and cannabis use in the past year in adolescents (RR =  0.55, 95 % CI 0.32–0.95 and RR = 0.44 95 % CI 0.20–0.96 respectively, at 6 year follow-up) .

Parent and family socialisation for alcohol use

Interventions included within the program, such as parent and child clarification of expectations, appropriate discipline, management of strong emotions and effective communication, and children peer skills were found  in one cluster randomized study (N=846 families) analysed in a systematic review of 56 studies (RCTs 41; BA 14; ITS 1) (Foxcroft et al., 2008) to be effective in:

• reducing alcohol use, alcohol use without permission and first drunkenness in adolescents (NNT=9 over 4 years).

Teachers and parents partnership promotion for cigarette use

Training teachers to communicate with parents and build partnerships (3-day workshops), training manual and follow-up supervisory visits; weekly home-school learning and communicating activities and workshops for parents were found in 1 RCT (N= 678) analysed in a systematic review of 22 RCTs (Thomas et.al., 2007), to be effective in:

• reducing cigarette use in adolescents (OR = 0.55, 95 % CI 0.34–0.88, p = 0.013 over 7 years).

Home visitation for disadvantaged families

Home visitation for families composed of low-income unmarried women was found in one study (N= 743) analysed in a narrative review to be mildly effective at 15-year follow-up (Toumbourou et al., 2007) in reducing for the parent(s):

• number of cigarettes smoked per day (1.50 versus 2.50, p = 0.10);
• number of days having consumed alcohol in the past six months (1.09 versus 2.49, p = 0.03).

Trade-off between benefits and harms

No interventions met the criteria for this category.

Unknown effectiveness

Standalone parental training

Parental training, not associated with children training resulted in a narrative report of 9 studies (Bühler and Kröger, 2006):

• improved children’s educational behaviour;
• reduced children’s problem behaviour;

but did not influence substance consumption.

Evidence of ineffectiveness

No interventions met the criteria for this category.

References and definitions

List of references

• Bühler A. and Kröger C. (2006), ‘Report on the prevention of substance abuse’, Federal Centre for Health Education BZgA (English version) | (German version)
• Foxcroft D., Ireland D., Lowe G. and, Breen R. (2008), ‘Primary prevention for alcohol misuse in young people’, Cochrane Database of Systematic Reviews 2002, Issue 3. Art. No.: CD003024. DOI: 10.1002/14651858.CD003024
• Gates S., McCambridge J., Smith LA. and Foxcroft D. (2006), ‘Interventions for prevention of drug use by young people delivered in non-school settings’, Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD005030. DOI: 10.1002/14651858.CD005030.pub2.
• Storr C.L., Ialongo N.S., Kellam S.G., Anthony J.C. (2002), ‘A randomized controlled trial of two primary school intervention strategies to prevent early onset tobacco smoking’, Drug Alcohol Dependence, Mar 1;66(1):51-60.
• Thomas R.E., Baker P.R.A. and Lorenzetti D. (2007), ‘Family-based programmes for preventing smoking by children and adolescents’, Cochrane Database of Systematic Reviews 2007, Issue 1. Art. No.: CD004493. DOI: 10.1002/14651858.CD004493.pub2.
• Toumbourou J.W., Stockwell T., Neighbors C., Marlatt G.A., Sturge J. and Rehm J. (2007), ‘Interventions to reduce harm associated with adolescent substance use’, Lancet 2007; 369: 1391–401. DOI:10.1016/S0140-6736(07)60369-9

Explanation of terms used

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.

Affective-focused prevention intervention

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).

BA

Before-after (BA) study design

Beneficial

Interventions for which precise measures of the effects in favour of the treatment were found in the systematic review of randomised controlled trials (RCTs), and that were recommended in guidelines with reliable methods for assessing evidence (such as GRADE). A treatment ranked as 'beneficial' is suitable for most patients.

CBA

Controlled before-after (CBA) study design

CCT

Controlled clinical trials (CCT)

Confidence Interval (CI)

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.

Practical interpretation

• If the RR (the relative risk) = 1, or the CI (the confidence interval) = 1, then there is no significant difference between treatment and control groups
• If the RR > 1, and the CI does not include 1, events are significantly more likely in the treatment than the control group
• If the RR < 1, and the CI does not include 1, events are significantly less likely in the treatment than the control group

CPS

Current population survey (CPS)

Evidence of ineffectiveness

Interventions that gave negative results if compared with a placebo, for example.

Additional information for prevention
For ethical reasons this category in prevention should be considered as interventions with negative and undesired (iatrogenic) effect.

ITS

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.

Likely to be beneficial

Interventions that were shown to have limited measures of effect, that are likely to be effective but for which evidence is limited, and those that are recommended with some caution in guidelines with reliable methods for assessing evidence (such as GRADE). A treatment ranked as 'likely to be beneficial' is suitable for most patients, with some discretion.

Number Needed to Treat (NNT)

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.

Odds Ratio (OR)

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

p value

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.

RCT

Randomised controlled trial (RCT)

Relative Risk (RR)

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.

Practical interpretation

• If the RR (the relative risk) = 1, or the CI (the confidence interval) = 1, then there is no significant difference between treatment and control groups
• If the RR > 1, and the CI does not include 1, events are significantly more likely in the treatment than the control group
• If the RR < 1, and the CI does not include 1, events are significantly less likely in the treatment than the control group

Trade-off between benefits and harms

Interventions that obtained measures of effects in favour of treatment and are recommended in guidelines with reliable methods for assessing evidence (such as GRADE), but that showed some limitations or adverse effects that need to be assessed before providing them to patients.

Unknown effectiveness

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'.

Skill-focused prevention intervention

A type of prevention intervention which aims to enhance students’ abilities in generic skills, refusal skills and safety skills.

Standardised Mean Difference (SMD)

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.

z score (Standard Score)

The z-score (aka, a standard score) indicates how many standard deviations an element is from the mean of the population.

Case definition

Prevention programmes can be delivered to family-as-a-system with or without any prior screening for vulnerability. The former programmes are general interventions targeting any family, whereas the latter are developed specifically to address families at risk of drug-related problems. Despite the lack of a common European definition, vulnerable families can be considered as families where one or more members misuse alcohol and/or drugs, and/or families with high levels of parental conflict and violence, poor quality of relations, family distruption and/or serious economic problems.

Risk

Studies from Member States most frequently reported the following factors to be associated with drug use among children: drug and alcohol abuse among parents, substance use of older siblings, lack of parental supervision, low quality of family relations, family distruption and problematic economic conditions. European and international research indicates that children of drug-dependent parents have an increased risk of substance use, abuse, and dependence in later adolescence. The risk conditions of families — including problem substance use, conflict, neglect, lack of parental monitoring, lower levels of interaction between young people and their families and social disadvantage - are known to increase the risk of problem drug use for their offspring. While lack of parental monitoring can occur both in single-parent and in economically affluent families, parental discipline and monitoring, and family cohesion, all play an important protective role.

Interventions

Interventions included in this section involve children and/or family members and aim to hinder or limit the use of substances, or to change family communication and interaction. Also interventions with school- or community-based components were included, provided the family-based component was predominant.

Outcomes

The main aim of prevention interventions delivered to families is to deter or to delay the onset of substance use/mis-use by providing all individuals (either targeting parental functioning or parent-children relationships) with the information and skills necessary to prevent the problem.

Primary outcomes

• Reduction of substance use
• Reduction of risky behaviour
• Reduction of intention to use
• Increase in awareness

References

• Velleman, R. D., Templeton, L. and Copello, A. (2005), ‘The role of the family in preventing and intervening with substance use and misuse: a comprehensive review of family interventions, with a focus on young people’, Drug and Alcohol Review 24(2), 93–109.
• Sumnall, H., Jones, L., Burrell, K., Witty, K., McVeigh, J. and Bellis, M. (2006), Annual Review of Drug Prevention, National Collaborating Centre for Drug Prevention, Liverpool.
• Thomas R.E., Baker P.R.A. and Lorenzetti D. (2007), ‘Family-based programmes for preventing smoking by children and adolescents’, Cochrane Database of Systematic Reviews 2007, Issue 1. Art. No.: CD004493. DOI: 10.1002/14651858.CD004493.pub2
• EMCDDA (2008), Drugs and vulnerable groups of young people, EMCDDA, Lisbon