%0 Journal Article %@ 2291-5222 %I JMIR Publications %V 9 %N 1 %P e24424 %T Developing an Adaptive Mobile Intervention to Address Risky Substance Use Among Adolescents and Emerging Adults: Usability Study %A Coughlin,Lara N %A Nahum-Shani,Inbal %A Philyaw-Kotov,Meredith L %A Bonar,Erin E %A Rabbi,Mashfiqui %A Klasnja,Predrag %A Murphy,Susan %A Walton,Maureen A %+ Department of Psychiatry, Addiction Center, University of Michigan, 2800 Plymouth Rd, Ann Arbor, MI, 48109, United States, 1 734 615 4774, laraco@med.umich.edu %K mHealth %K adolescents %K young adults %K just-in-time adaptive intervention %K alcohol misuse %K cannabis %K mobile phone %D 2021 %7 15.1.2021 %9 Original Paper %J JMIR Mhealth Uhealth %G English %X Background: Substance use among adolescents and emerging adults continues to be an important public health problem associated with morbidity and mortality. Mobile health (mHealth) provides a promising approach to deliver just-in-time adaptive interventions (JITAIs) to prevent escalation of use and substance use–related consequences. Objective: This pilot study aims to describe the iterative development and initial feasibility and acceptability testing of an mHealth smartphone app, called MiSARA, designed to reduce escalation in substance use. Methods: We used social media advertisements to recruit youth (n=39; aged 16-24 years, who screened positive for past-month binge drinking or recreational cannabis use) with a waiver of parental consent. Participants used the MiSARA app for 30 days, with feasibility and acceptability data reported at a 1-month follow-up. We present descriptive data regarding behavior changes over time. Results: The results show that most participants (31/39, 79%) somewhat liked the app at least, with most (29/39, 74%) rating MiSARA as 3 or more stars (out of 5). Almost all participants were comfortable with self-reporting sensitive information within the app (36/39, 92%); however, most participants also desired more interactivity (27/39, 69%). In addition, participants’ substance use declined over time, and those reporting using the app more often reported less substance use at the 1-month follow-up than those who reported using the app less often. Conclusions: The findings suggest that the MiSARA app is a promising platform for JITAI delivery, with future trials needed to optimize the timing and dose of messages and determine efficacy. %M 33448931 %R 10.2196/24424 %U http://mhealth.jmir.org/2021/1/e24424/ %U https://doi.org/10.2196/24424 %U http://www.ncbi.nlm.nih.gov/pubmed/33448931