Efficacy of a Smartphone App. Designed to Manage Craving & Individual Predictors of Substance Use/Addictive Behavior

We will compare the percentage of participants for whom a 20% decrease in main problematic substance use / addictive behavior was observed between 1st week and 4 th week of smartphone application use in the experimental group versus the control group

Multifactorial addiction severity ASI "Composite Score" for the main problematic addiction (drug or alcohol or tobacco or behavioral addiction) : Range 0-1 (1: higher severity) and craving self-reported in the last EMA week, and reported in the Craving evaluation scale developed by the University of Bordeaux Addiction Team of the Sanpsy Laboratory will be used. It is an heteroevaluation of craving for all substances and addictive behaviors reported by the subject. This tool explores the frequency of craving, corresponding to the number of days craving was reported during the last 30 days, as well as mean and maximum intensity on a scale ranging from 0 (no craving) to 10 (extreme craving).

Comparison between baseline, 1-month et 4-month follow-ups of frequency, mean and maximum intensity of craving for main problematic addiction

Evaluation of the initial severity of addiction ASI "Composite Score" for the main problematic addiction (drug or alcohol or tobacco or behavioral addiction) : Range 0-1 (1: higher severity), initial craving frequency and intensity with craving evaluation scale, the type of addiction,comorbid psychiatric disorders (evaluated with Mini International Neuropsychiatric Interview), and past or concomitant addiction treatment (evaluated by ASI and Treatment Service Review).

During the 4 weeks use of the application, all participants will be instructed to complete 4 daily EMA electronic interviews to assess craving-and substance use/addictive behavior (see Serre, Fatseas et al. 2012). At each electronic interview, participants will be asked to rate the maximum level of craving (i.e. the desire to use the main substance/addictive behavior) that they felt since the previous assessment on a seven-point scale (1 no desire to 7 extreme desire), and will also be asked if they had used, since the previous assessment, the main substance/addictive(yes/no)

• The evolution and temporal trajectories of substances use/addictive behaviors measured with EMA in daily life

Feasibility will be assessed at the 1-month follow-up by number of days and frequency of use of the application (calculated from EMA responses: number of questionnaires answered on total number of questionnaires proposed by the application), rate of participants not completing the study, and reasons for stopping

Acceptability will be assessed at 1-month follow-up with AES, D-WAI and uMARS. The Acceptability E-scale (AES) is a 6-item questionnaire that evaluates the extent to which subjects find E-health systems acceptable. Each item is ranked on a 5-point Likert scale, generating a total score of acceptability ranging from 6 (lowest acceptability) to 30 (highest acceptability) (Micoulaud-Franchi, Sauteraud et al. 2016). The Digital Working Alliance Inventory (D-WAI) measures factors (goals, tasks and bond) to examine the therapeutic relationship between the participant and the app (Henson et al., 2019). The user version of the Mobile Application Rating Scale (uMARS) is a simple tool that can be reliably used by end-users to assess the quality of mHealth apps (Stoyanov et al., 2016).

Impact of the 4 weeks use of the smartphone application Potential impact (positive or negative) of the 4 weeks use of the smartphone application on subsequent treatment will be assessed at 4-month follow-up with rate of first-time attendance to the standard treatment, time to first-time attendance to the standard treatment, compliance with standard treatment (Treatment Service Review), and evolution of severity of addiction during the standard treatment (ASI Composite Score). Follow-ups measures will be compared to baseline measures, and the difference will be compared between the two groups.

Intervention Satisfaction will be assessed at 1-month follow-up with the Client Satisfaction Questionnaire (CSQ-8), that is a multi-item measure of satisfaction related to healthcare (Larsen et al., 1979; Kapp et al., 2014). The CSQ-8 total score ranges from 8 to 32. A higher score represents greater satisfaction