The impact of a stage tailored intervention on alcohol use trajectories among those who do not intend to change

Background: Persons not intending to change are an important target population for public health efforts. The aim of this study was to investigate whether subgroups characterized by different trajectories of alcohol use frequency and quantity among persons with unhealthy drinking but no intention to change benefitted differently from a stage tailored intervention.

Methods: This study was part of a randomized controlled trial among job-seekers. The participants of the intervention group (n=413) received feedback letters tailored to their motivational stage. The control group (n=414) received minimal assessment only. Among all participants, 629 (76.1%) did not intend to change alcohol use and constitute the study sample (60.7% men; mean age=29.7 years, SD=10.8). 3-, 6-, and 15-month follow-ups were conducted. Growth mixture modeling was applied to identify classes representing the heterogeneity in the development of alcohol use frequency and quantity and the influence of the intervention on different trajectories.

Results: Four classes were identified: a class of persons who achieved abstinence (2%), a class with low-frequent drinking with declining quantity (35%), a class with high-frequent drinking with low but slightly increasing quantity (30%), and a class with constant heavy episodic drinking (33%). Although non-significant, there was a tendency of different intervention effects for different classes.

Conclusions: A sample of persons not intending to change unhealthy alcohol use was composed of subgroups characterized by different trajectories of alcohol use quantity and frequency. Trends towards beneficial intervention effects on motivation and drinking outcomes were not significant, possibly due to low power.