Supplementary Material for: Evaluation of a Smartphone App Intervention with Telephone Guidance as Transitional Support from Inpatient Treatment to Continuing Care for Individuals with Alcohol Use Disorder: Results from a Randomized Controlled Trial

Introduction: Relapse rates in individuals with alcohol use disorder (AUD) are particularly high following inpatient treatment. Innovative strategies should specifically target the transitional gap between completion of inpatient treatment and uptake of standard continuing care. This study aimed to determine whether Appstinence, a digital approach that combines a smartphone app intervention with adjunct telephone coaching, more markedly reduces the risk of relapse for 6 months after inpatient AUD treatment in comparison to a control group with access to standard continuing care.

Methods: In this multicenter clinical trial, 356 participants were randomized to the intervention (n=175) or control group (n=181). Eligibility criteria included diagnosis of AUD, smartphone access, no acute suicidality, and no language or neurocognitive impairments. The primary outcome was risk of relapse within six months after randomization, as assessed with the Timeline-Follow-Back method. Secondary outcomes included uptake of standard continuing care, hazardous alcohol consumption, craving, depression and anxiety symptom severity, and well-being.

Results: The intervention reduced the risk of relapse within six months as indicated by a log-rank test (HR 0.72, 95% CI 0.53-0.98, p=0.04) and Cox regression adjusted for baseline characteristics (HR 0.67, 95% CI 0.48-0.92, p=0.01). This effect increased when participants fully adhered to the intervention protocol (log-rank test: HR 0.61, 95% CI 0.39-0.94, p=0.02). No significant differences were observed in secondary outcomes.

Conclusion: Our findings provide supportive evidence for digital AUD transition treatment. Specifically, we found that, in comparison with access standard continuing care, the novel intervention more effectively reduced risk of relapse within six months following inpatient treatment.