Comparing Profiles of the Transtheoretical Model of Change Constructs for Reducing Cannabis Use Among Trauma Patients

Background: The Transtheoretical Model (TTM) is a foundational framework of many interventions that target substance use behavior change. Prior research has found that profiles of successful substance use behavior change can be captured by comparing the mean scores of TTM constructs between changers and non-changers. However, no prior study has investigated TTM construct profiles among trauma patients with a history of substance use. TTM construct profiles may be unique for trauma patients due to the impact of traumatic events on mechanisms of substance use behavior change. Thus, examining TTM construct profiles for specific substance use behaviors may inform knowledge of markers for successful behavior change among this population. This study’s purpose was to investigate TTM construct profiles for cannabis use behavior change among trauma patients. We focused on cannabis use due to its high prevalence among traumatic injury victims.

Methods: Study data came from The Traumatic Injury Prevention Project (TIP), a three-group, single-site randomized clinical trial conducted in a level-1 urban trauma center. Participants included adults who were admitted for a traumatic injury and screened positive for past-month substance use. The TTM constructs of pros for change, cons for change, confidence to change, temptation, experiential processes of change, and behavioral processes of change for cannabis use were combined to form the construct profiles. Profile analysis (PA) was used to examine the end-of-treatment (3 months post-intake) mean profiles of TTM constructs for two cannabis use-outcome-based groups (abstinence vs. any cannabis use at 12-months post-intake). PA is a form of multivariate analysis of variance (MANOVA) for repeated measures that can be used when several dependent variables (e.g., individual TTM constructs) are measured simultaneously. The raw mean scores of each construct were transformed into z scores, which is consistent with the PA assumption that each dependent variable is measured on the same metric.

Results: PA results showed a significant parallelism effect (p<.001), suggesting differences in the profiles of abstainers and those who used cannabis at 12 months. Additionally, significant differences were found between the two groups on the individual TTM constructs of confidence to change, temptation, and behavioral processes of change. Compared to those who used cannabis, abstainers reported greater confidence to change (p<.001), lower temptation to use cannabis (<.001), and greater behavioral processes of change (p<.05).

Conclusions and Implications: The differences in the end-of-treatment TTM construct profiles between cannabis abstainers and those who used cannabis at 12 months have clinical and research implications. That abstainers exhibited higher confidence to change, higher use of behavioral processes, and lower temptation to use cannabis is generally consistent with findings from previous studies that examined TTM construct profiles of at-risk drinking. Study findings suggest that emphasizing these TTM constructs may be salient for clinicians working with clients with a history of traumatic injury and substance use. Replication of these findings for other substance use behaviors among trauma patients is a pragmatic next step for future research. Further study is also needed to investigate how individual TTM profiles can be integrated into existing substance use interventions.