Introduction Suicidal ideation is common in young people and increases the risk of suicide. Effective interventions that are relevant and accessible to young people, so-called digital natives, are urgently required.
There are key questions regarding the cross-cultural efficacy of suicide prevention applications (apps) for scalability. Methods and analysis This online four-arm parallel randomised controlled superiority trial will enrol 1480 young people aged 16 - 24 years with current suicidal ideation in New Zealand and Australia.
Participants will be randomised to one of three therapeutic apps developed in different countries, Tune In, Bro and LifeBuoy, or to My Mood (attention control). The primary outcome is suicidal ideation severity at 30-day and 90-day post-baseline; secondary outcomes include mental well-being, engagement and acceptability.
Emotional regulation will be examined as a mediator of change in suicidal ideation. All outcomes are measured by self-reported scales incorporated in an online questionnaire.
Acceptability of the apps for rangatahi Māori (Indigenous youth, New Zealand) will be explored via semi-structured interviews.
Suicidal thoughts are prevalent among adolescents and young adults and constitute a major risk factor for suicide.
The protocol outlines a trial designed to test whether digital interventions—mobile applications—can reduce severity of suicidal ideation in young people aged 16–24.
A secondary aim is to evaluate cross‑jurisdictional performance of apps originally developed in different countries and to explore mechanisms such as emotion regulation.
The trial is an online, four‑arm, parallel, superiority randomized controlled study.
Enrolled participants are allocated to one of four smartphone apps: three therapeutic interventions (Tune In, Bro, LifeBuoy) and an attention control app (My Mood).
All outcome data are collected through self‑report questionnaires administered online.
Planned recruitment is 1,480 individuals reporting current suicidal ideation, drawn from two jurisdictions—New Zealand and Australia.
The protocol includes a focused qualitative component to assess acceptability among rangatahi Māori (Indigenous youth in New Zealand) via semi‑structured interviews.
The primary endpoint is severity of suicidal ideation at 30 and 90 days after baseline.
Secondary endpoints include measures of mental well‑being, user engagement, and acceptability.
Emotion regulation is specified as a putative mediator of change in suicidal ideation.
The statistical approach comprises linear mixed models for repeated measures using maximum likelihood estimation, selection of an appropriate covariance structure, and adjustment for site effects.
The protocol also proposes examining intervention effects separately by country to identify cross‑cultural differences in app performance.
Ethics approval was obtained from the Health and Disability Ethics Committees (Ministry of Health reference 2025 EXP 21500) on 26 February 2025.
Participants provide online informed consent.
Planned dissemination includes peer‑reviewed publication, website posting, and presentations at international conferences.
Individual participant data will be made available only upon request and subsequent review.
The protocol specifies self‑report assessment only; no clinician‑rated measures are reported.
Details regarding recruitment procedures, retention strategies, sample size justification, and safety monitoring are not described in this summary.