These notes expand on the related studies and reviews summarised in the commentary on the study featured in the main entry.
The only previous study to compare feedback alone with motivational interviewing with and without assessment feedback recruited As compensation, participants received up to five experimental psychology course credits or monetary compensation of $5 per hour. a small sample of relatively heavy drinking US college students. Generally the results were inconclusive with no significant impacts on drinking though some favouring feedback-based interventions in respect of symptoms of alcohol dependence and (among only the women) drink-related problems. The tentative conclusions were that on these measures, motivational interviewing benefited from assessment feedback, and that if it came to a choice between unelaborated feedback and motivational interviewing without feedback, the former more effectively reduced dependence symptoms.
A few previous studies have contrasted feedback alone with feedback incorporated in a motivational interview. One US study found no differences in drinking reductions six months later. However, in this study heavy drinking college students The authors explain that "Potential participants were recruited through an extra credit screening available to undergraduate students enrolled in psychology and communications courses." Three quarters of screened students were women. were not just given the feedback but instructed to think about it for half an hour in the study's intervention room, and feedback was accompanied by written risk reduction advice. Moreover, the motivational interview seemed too explicitly directive to be a faithful implementation. In other words, the 'feedback' was actually much more than feedback, and the 'motivational interview' may not have really qualified for that designation, perhaps accounting for the 'no difference' finding.
Another US college study initially (four months after intervention) found no differences in drinking reductions. But after 15 months there were signs that compared to written feedback only, the face-to-face interview led to better retention of initial reductions in drinking and related problems. This pattern may be because the study recruited students caught violating university rules on alcohol. Being caught and facing sanctions in itself leads to drinking reductions, perhaps initially overwhelming the motivational interview.
Two rather different studies concerned patients identified as risky drinkers in hospital emergency departments. In a US trauma centre, young adults were randomly allocated to feedback delivered in person but with minimal interaction Counsellors introduced the feedback report as providing information about how much the patients drink and what happens when they drink, and how they compare to others their age. Conversation was minimal, but any questions or concerns were addressed appropriately. Contact lasted from one to three minutes. or to the same feedback incorporated in a motivational interview. Six and 12 months later the interview led to substantially greater reductions in drinking.
A similar study in Sweden but not confined to young adults compared brief face-to-face feedback with this plus professional counselling lasting over an hour to explore the patient's concerns, compare their intake to safer drinking limits and population norms, and to offer further counselling and tests for impaired brain function. Re-assessment six and 12 months later revealed no greater reductions in drinking from the longer intervention. It may be relevant that even in the shorter intervention patients were advised that their drinking probably put them at risk, and that the longer intervention was not a motivational interview.
This is not to say that mere feedback is ineffective. It was ineffective in the featured study, and also failed to create statistically significant changes in most of the 14 studies of feedback-only interventions included in a recent meta-analysis. Yet when that analysis amalgamated results across the studies, it found a statistically significant small to medium size reduction in alcohol consumption. All but one of the 14 studies had recruited non-treatment seekers from the community, and nine involved higher education students.
All these studies left open the question of whether other counselling/information-giving styles might have been just as effective as motivational interviewing. That issue was addressed in three reviews. The first analysed 42 studies which trialled interventions aimed at individual students. As opposed to interventions like campus-wide media campaigns or alcohol availability restrictions. No support was found for those which confined themselves to imparting information or knowledge, or for brief 'values clarification' approaches alone or with other information content. There was some mixed evidence for skills-based interventions, including self-monitoring or self-assessment. The 'normative' tactic of attempting to correct student's over-estimates of how much their peers drink worked best when it was personalised to the individual, setting their drinking and/or risks alongside national or local norms. But the evidence was most consistent for interventions which incorporated this and other feedback in a brief motivational intervention. A second review of 15 studies reached very similar conclusions.
The verdicts of these reviews were confirmed by a review and meta analysis which aggregated results from 62 studies evaluating alcohol abuse prevention among student drinkers. Nearly half trialled motivational interviewing techniques and just over half compared the student's drinking with population norms. This quantitative analysis found that individual, face-to-face interventions using motivational interviewing and featuring personalised feedback led to the greatest reductions in alcohol-related problems. Specific forms of feedback associated with larger effects included normative comparison of the individual's drinking with population norms, and feedback on their expectations of, or motives for, drinking.
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