JMIR Publications

ABSTRACT

Background:

Non-suicidal self-injury (NSSI), the deliberate, self-inflicted damage of body tissue without suicidal intent, is increasingly prevalent among adolescents and young adults and poses a major public health concern. Current treatments are often costly, difficult to access, and not tailored to the specific needs of young people. Mobile health (mHealth) interventions represent a promising avenue for scalable, accessible, and cost-effective support for NSSI, especially when combined with real-time assessments and personalized treatment strategies.

Objective:

This randomized controlled trial (RCT) will evaluate the effectiveness of Kalmer, a brief app-based intervention for reducing NSSI and improving emotional well-being. The study has three aims: (1) To evaluate a newly developed app-based intervention program for adolescents and young adults engaging in NSSI. (2) To assess predictors of treatment outcomes from this app-based intervention program. We hypothesize that participants receiving a mobile app-based brief intervention specifically tailored to address NSSI, will show a greater reduction in the frequency of NSSI at the end of treatment and at follow-up compared to participant receiving a non-specific App-based intervention. In this paper, we present our study protocol

Methods:

This 2-armed randomized controlled trial (RCT) lasting 6 weeks will include 240 participants with NSSI aged 14–24. The intervention app, Kalmer, was developed through iterative consultation with clinical and research experts, guided by survey results and evidence-based frameworks such as Dialectical Behavior Therapy (DBT) and Cognitive Behavioral Therapy (CBT). The intervention will include five core components: Distress Tolerance, Emotion Regulation, Mindfulness and Self-Compassion, Interpersonal Regulation, and Problem-Focused Coping. The app will deliver multimedia-based ecological momentary interventions (EMIs) triggered by real-time ecological momentary assessments (EMAs) to tailor support to users’ current context and needs. Participants are randomized to receive either the Kalmer intervention or psychoeducational control app. Primary outcomes include NSSI frequency and emotional regulation, assessed through EMAs and self-report at baseline, post-intervention (6 weeks), and follow-ups (1 and 3 months).

Results:

Ethics approval was obtained in December 2022. As of July 2025, 119 participants have consented to participate in our study and completed baseline assessments. Preliminary data shows high app engagement and acceptability, and positive user feedback on app usability and content. Recruitment is ongoing

Conclusions:

This study will provide evidence on the effectiveness of a mobile app–based intervention for NSSI and explore mechanisms of change, supporting the development of accessible digital mental health tools for youth. Clinical Trial: ISRCTN Registry ISRCTN63093907; https://www.isrctn.com/ISRCTN63093907