“Customize it to that population, my population, my people, my peeps.” Qualitative Evidence of Usability, Appropriateness, and Feasibility of an Anxiety-Facing Mobile Application for Co-Occurring Substance Use and Anxiety Disorders

Despite the rapid growth of app-based interventions (ABIs), effective and accessible tools for individuals with co-occurring anxiety and substance use (A-SUD) remain limited. Most usability studies of ABIs for substance use rely on quantitative methods and rarely focus on anxiety comorbidity. To address this gap, we conducted longitudinal qualitative interviews with 24 participants in SUD treatment (peer-led, n=11; pharmacotherapy, n=9; psychotherapy, n=4) over a two-month period. The study aimed (1) to assess the acceptability, appropriateness, and feasibility of the Unwinding Anxiety app as an adjunctive support for SUD treatment among patients with A-SUD ; (2) identify needed modifications to optimize it for A-SUD. Participants found the app's features and skills useful and relevant but emphasized the need for additional substance use-specific content. Findings underscore the value of evidence-based, step-by-step digital interventions for enhancing and complementing SUD care across treatment modalities. Future research should build on reinforcement learning and interoceptive awareness principles to better tailor ABIs for substance use.