Motivational interviewing for alcohol misuse in young adults

Globally, harmful use of alcohol results in approximately 2.5 million deaths each year. About 9% of these deaths are young people between the ages of 15 and 29 years (WHO 2011), mainly resulting from motor vehicle accidents, homicides, suicides and drownings. Hazardous drinking levels for men (consuming over 40 g/day alcohol on average, that is 5 units) double the risk of liver disease, raised blood pressure, some cancers and violent death (because some people who have this average alcohol consumption drink heavily on some days). For women, over 24 g/day average alcohol consumption (3 units) increases the risk for developing liver disease and breast cancer. Motivational interviewing (MI) is a popular technique for addressing excessive drinking in young adults but its effectiveness has not previously been examined in a Cochrane review.

The specific objectives were:(1) to summarise current evidence about the effects of MI intended to address alcohol and alcohol-related problems in young adults, compared with no intervention or a different intervention, on alcohol consumption and other substantive outcome measures;(2) to investigate whether the effects of MI are modified by the length of the intervention.

Relevant evidence was identified from (1) Cochrane Central Register of Controlled Trials (CENTRAL) (October 2013), (2) MEDLINE (January 1966 to October 2013), (3) EMBASE (January 1988 to October 2013), and (4) PsycINFO (1985 to October 2013). References of topic-related systematic reviews and the included studies were handsearched.

Randomised controlled trials and cluster randomised controlled trials of young people up to the age of 25 years in college and non-college settings comparing MIs with no intervention or a different intervention for prevention of alcohol misuse and alcohol-related problems were included.

We used the standard methodological procedures expected by The Cochrane Collaboration.

A total of 66 randomised trials (17,901 participants) were included four of which were cluster randomised. Studies with longer-term follow-up (four plus months) were of more interest when considering the sustainability of intervention effects.At four or more months follow-up, effects were found for the quantity of alcohol consumed (standardised mean difference (SMD) -0.14; 95% confidence interval (CI) -0.20 to -0.08 or a reduction from 13.7 drinks/week to 12.2 drinks/week), moderate quality of evidence; frequency of alcohol consumption (SMD -0.11; 95% CI -0.19 to -0.03 or a reduction in the number of days/week alcohol was consumed from 2.74 days to 2.57 days), moderate quality of evidence; and peak blood alcohol concentration (BAC) (SMD -0.14; 95% CI -0.23 to -0.05 or a decrease in peak BAC from 0.144% to 0.129%), moderate quality of evidence. A marginal effect was found for alcohol problems (SMD -0.08; 95% CI -0.15 to 0.00 or a reduction in an alcohol problems scale score from 8.91 to 8.18), low quality of evidence. No effects were found for binge drinking (SMD -0.05; 95% CI -0.12 to 0.01), moderate quality of evidence; or average BAC (SMD -0.08; 95% CI -0.22 to 0.06), moderate quality of evidence. We also considered other outcomes and at four or more months follow-up we found no effects on drink-driving (SMD -0.11; 95% CI -0.31 to 0.09), moderate quality of evidence; or other alcohol-related risky behaviour (SMD -0.14; 95% CI -0.30 to 0.02), moderate quality of evidence.Further analyses showed that the type of control comparison (assessment only versus alternative intervention) did not predict the outcome in a clear or straightforward way; and there was no consistent relationship between the duration of the MI intervention (in minutes) and effect size.

The results of this review indicate that there are no substantive, meaningful benefits of MI interventions for the prevention of alcohol misuse. Although some significant effects were found, we interpret the effect sizes as being too small, given the measurement scales used in the studies included in the review, to be of relevance to policy or practice. Moreover, the statistically significant effects are not consistent for all misuse measures, heterogeneity was a problem in some analyses and bias cannot be discounted as a potential cause of these findings.