Trajectory classes of engagement with an alcohol text message intervention and predictors of intervention engagement

Digital interventions have increased our capacity to reach young adults who have hazardous alcohol use. Alcohol text message interventions have shown small effects in reducing hazardous drinking, leaving room for improvement. An important challenge to address in improving digital interventions is maintaining engagement, which reflects the "dose" of intervention received. This study aimed to identify trajectory classes of engagement with an alcohol text message intervention, and baseline predictors of the trajectory classes to determine "for whom" the digital intervention was more versus less engaging, to guide further intervention tailoring. This secondary analysis examined data from a study that compared five 12-week alcohol text message interventions designed to reduce hazardous drinking in young adults (aged 18-25; N = 1,131, 68% female) recruited from Emergency Departments in Western Pennsylvania. Engagement with the intervention was based on response (present/absent) to text message queries delivered twice per week during 2-week run-in and 12-week intervention. Repeated measures latent profile analysis identified five latent trajectory classes as having the best fit to the data: "High engagement" (55.1%), "Slow decrease, moderate engagement" (23.2%); "Mid-way decrease in engagement" (8.9%), "Steadily decreasing engagement" (8.1%); and "Fluctuating, moderate engagement" (4.6%). Females and individuals enrolled in college were overrepresented in the high engagement trajectory class, whereas individuals higher in impulsivity were more likely to be in decreasing (versus high) engagement trajectory classes. Methods to boost engagement using, for example, motivational enhancement for young adults with higher levels of impulsivity, at specific time points, such as the mid-point of the intervention, warrant consideration.