Introduction: The influence of age on brief motivational interventions (BMI) effects remains unknown. In the present study, we explored whether change in alcohol consumption after BMI differs across age groups and whether these differences are reflected in motivational interviewing (MI) counsellor skills.

Method: Secondary analysis of a randomized controlled trial among emergency room (ER) patients screened for unhealthy alcohol consumption. Participants (N = 97, 80 % men, 18–21 y: 19.6 %, 22–29 y: 22.7 %, 30–49 y: 34.0 % and ≥50 y: 23.7 %) received a single BMI in the ER, which was coded using the MI Skills Code 2.0. Alcohol outcomes were measured at 12-month. First, we tested whether BMI effect varied by age group using negative binomial regression for weekly drinking consumption, and logistic regression for change to low-risk drinking. Second, MI counsellor skills (global ratings of empathy, MI spirit and acceptance, and percentages of open questions, complex reflections (CR) and MI-consistent behaviors) were examined through one-way ANOVA or Welch test.

Results: The 22–29 y group i) reported lower consumption at follow-up compared to the 30–49 y group (IRR=1.60, p = .04) and the ≥ 50 y group (IRR=1.67, p = .03), and ii) was more likely to change to low-risk drinking than the 18–21 y group (OR=11.25, p = .04). When comparing MI counsellor skills across age groups, higher empathy ratings (F(3,93)= 2.70, p = .05) and a higher percentage of CR (F(3,93)= 4.10, p = .009) were recorded for the 22–29 y group.

Conclusion: This exploratory study shows that BMI was associated with significantly better 12-month alcohol outcomes among patients aged 22–29 years, which corresponded with higher counsellor empathy ratings and percentage of CR.