JMIR Publications

ABSTRACT

Background:

Brief interventions such as counselling or individualized feedback have been found to be effective in alcohol users who exceeded low-risk drinking limits. Recent evidence has indicated that alcohol consumption below these limits is also associated with substantial health risks, such as elevated probabilities for adverse brain and cardiovascular outcomes as well as prevalent cancers. To maximize their public health impact, brief interventions should be targeted at all alcohol users, raising questions regarding their applicability to the broader population. As they have been most often excluded from brief alcohol intervention trials, little is known on the efficacy of brief interventions for alcohol use below low-risk drinking levels.

Objective:

The aims were (i) to test the long-term effects of computer-generated individualized feedback letters among individuals who consume alcohol, irrespective of how much; and (ii) to explore how the intervention effects may be moderated by alcohol use severity and school education.

Methods:

In the waiting area of the municipal registry office in Greifswald, Mecklenburg-Western Pomerania, Germany, a general population sample of 1,646 adults (56% women; mean age = 31.0 years) who reported alcohol use at least once in the past year were randomized to an intervention (n = 815) or control group (n = 831). The intervention comprised up to three computer-generated individualized feedback letters based on the Transtheoretical Model of Behavior Change at baseline and after 3 and 6 months. The control group received assessment only. The outcome was change in self-reported number of drinks per week from baseline to follow-up after 36 and 48 months. Moderators of intervention efficacy were self-reported alcohol use severity (low-risk vs. at-risk drinking) and school education (less than 12 years vs. 12 or more years) at baseline.

Results:

Unadjusted and adjusted latent growth models revealed no group difference after 36 months (Incidence rate ratio IRR = 1.05; 95% Confidence interval 95% CI = 0.87-1.27; Bayes factor BF = 0.37). After 48 months, a decrease in weekly alcohol consumption was observed in the control group and no change in the intervention group (IRR = 1.29; 95% CI = 1.05-1.57; BF = 0.16), indicating strong evidence against the hypothesized intervention effect. Intervention efficacy was not moderated by alcohol use severity or school education at baseline.

Conclusions:

In a randomized controlled trail, no evidence for the efficacy of individualized feedback letters was found after three and four years. Unexpectedly, drinking reductions in the control group and no change in the intervention group were observed four years after study start. Intervention strategies effective in at-risk drinkers may necessitate adaptation for applicability to alcohol users as a whole. Clinical Trial: The trial was prospectively registered at the German Clinical Trials Register (DRKS00014274, date of registration: 12th March 2018).