Therapist and computer-based brief interventions for drug use within a randomized controlled trial: effects on parallel trajectories of alcohol use, cannabis use and anxiety symptoms

Abstract

Background and aims: Despite their high comorbidity, the effects of brief interventions (BI) to reduce cannabis use, alcohol use and anxiety symptoms have received little empirical attention. The aims of this study were to examine whether a therapist-delivered BI (TBI) or computer-guided BI (CBI) to address drug use, alcohol consumption (when relevant) and HIV risk behaviors, relative to enhanced usual care (EUC), was associated with reductions in parallel trajectories of alcohol use, cannabis use and anxiety symptoms, and whether demographic characteristics moderated reductions over time.

Design: Latent growth curve modeling was used to examine joint trajectories of alcohol use, cannabis use and anxiety symptoms assessed at 3, 6 and 12 months after baseline enrollment.

Setting: Hurley Medical Center Emergency Department (ED) in Flint, MI, USA.

Participants: The sample was 780 drug-using adults (aged 18-60 years; 44% male; 52% black) randomly assigned to receive either a TBI, CBI or EUC through the HealthiER You study.

Interventions and comparator: ED-delivered TBI and CBIs involved touchscreen-delivered and audio-assisted content. The TBI was administered by a Master's-level therapist, whereas the CBI was self-administered using a virtual health counselor. EUC included a review of health resources brochures in the ED.

Measurements: Assessments of alcohol use (10-item Alcohol Use Disorders Identification Test), cannabis use (past 30-day frequency) and anxiety symptoms (Brief Symptom Inventory-18) occurred at baseline and 3-, 6- and 12-month follow-up.

Findings: TBI, relative to EUC, was associated with significant reductions in cannabis use [B = -0.49, standard error (SE) = 0.20, P < 0.05) and anxiety (B = -0.04, SE = 0.02, P < 0.05), but no main effect for alcohol use. Two of 18 moderation tests were significant: TBI significantly reduced alcohol use among males (B = -0.60, SE = 0.19, P < 0.01) and patients aged 18-25 years in the TBI condition showed significantly greater reductions in cannabis use relative to older patients (B = -0.78, SE = 0.31, P < 0.05). Results for CBI were non-significant.

Conclusions: Emergency department-based therapist-delivered brief interventions to address drug use, alcohol consumption (when relevant) and HIV risk behaviors may also reduce alcohol use, cannabis use and anxiety over time, accounting for the overlap of these processes.

Trial registration: ClinicalTrials.gov NCT01113190.

Keywords: Alcohol; anxiety; brief intervention; cannabis; emergency department; latent growth curve modeling.

© 2019 Society for the Study of Addiction.

Figures

Figure 1.

Joint process model showing that alcohol use, cannabis use, and anxiety levels decreased significantly across the whole sample from baseline to 12-month follow-up. Note. ***p < .001. Model fit statistics: CFI = .94; TLI = .92, RMSEA = .06, SRMR = .05. Standardized values reflect z-scores. Overall, across the whole sample, there was a reduction in alcohol use across the four time points, with significant variance in both starting levels (intercept) and linear change (slope): Means: Slope, B = −.04, SE = .01, p < .001, Intercept, B = .96, SE = .04, p < .001; variances: Slope, B = .01, SE = .006, p < .05. Intercept, B = .66, SE = .06, p < .001. There was also a reduction in cannabis use across time, with significant variance in both starting levels (intercept) and linear change (slope): Means: Slope, B = −.18, SE = .11, p = .11, Intercept, B = 13.08, SE = .40, p < .001; variances: Slope, B = 2.63, SE = .93, p < .01. Intercept, B = 86.07, SE = 5.20, p < .001. There was a significant correlation between the starting levels of anxiety and alcohol use (r = .31, p < .001), but not between anxiety and cannabis use or between alcohol and cannabis use. Finally, there were correlations between slope factors (i.e., correlation in linear change): alcohol and cannabis use, r =.35, p <.05; alcohol use and anxiety: r = .47, p < .05; cannabis and anxiety: r = .42, p < .05.

Figure 2.

Cannabis use showed a significant reduction over time from baseline to 12 months in the TBI group but not the control group. Note. *p < .05, n.s. = non-significant. There was a significant linear reduction in cannabis use over time in the TBI group (B = −.49, SE = .20, p < .05) but not the control group (B = .13, SE = .20, p = .50).

Figure 3.

Anxiety level showed a significant reduction over time from baseline to 12 months in the TBI group but not the control group. Note. *p < .05, n.s. = non-significant. There was a significant linear reduction in level of anxiety over time in the TBI group (B = −.04, SE = .02, p < .05) but not the control group (B = −.006, SE = .02, p = .74).

Figure 4.

Alcohol use showed a significant reduction over time from baseline to 12 months among males in the TBI group but not the control group. Note. **p < .01, *p < .05, n.s. = non-significant. There was a significant linear reduction in level of alcohol use over time among males in the TBI group (B = −.60, SE = .19, p < .01) but not the control group (B = −.15, SE = .18, p = .40) Among females, there was a slight decrease in alcohol use in the control group (B = −.21, SE = .11, p < .05) but the rate of alcohol use among females in the TBI group did not change significantly (B = −.08, SE = .12, p = .52).

Figure 5.

Participants aged 18–25 years old benefited most from the TBI relative to other age groups Note. *p < .05, †p < .10. The figure shows linear change in cannabis usage among individuals within the TBI group divided into four age categories: ages 18–25 (n = 101, ages 25–35 (n = 76), ages 36–45 (n = 45), and 46 years and older (n = 35). Individuals ages 18–25 years old who received TBI showed a significant reduction in cannabis usage (B = −.78, SE = .31, p < .05); individuals aged 26–35 within the TBI group also showed a modest reduction in cannabis use but was not significant (B = −.64, SE = .38, p = .09; individuals aged 36–45 years old within the TBI group did not show a significant change in usage (B = −.40, SE = .50, p = .43); finally, individuals aged 46 years or older within the TBI group actually showed a slight increase in cannabis use but was not significant (B = .54, SE = .31, p = .09).