Internet-based Emotion Regulation Individual Therapy for Adolescents (IERITA) plus treatment as usual versus treatment as usual for adolescent outpatients with non-suicidal self-injury—the TEENS multi-site trial: study protocol and statistical analysis plan for a multi-site randomised clinical trial

Abstract

Non-suicidal self-injury (NSSI) is a public health concern and a widespread behaviour, especially among adolescents. NSSI is an indicator of psychological distress and a known risk factor for later suicidal behaviour and death by suicide; however, evidence-based treatment options and early interventions specifically for NSSI in adolescents are sparse. The aim of the TEENS multi-site randomised clinical trial is to investigate the benefits and harms of the 11-week IERITA programme (Internet-based Emotion Regulation Individual Therapy for Adolescents) added to treatment as usual (TAU) versus TAU alone in 13- to 17-year-old patients with NSSI referred to psychiatric outpatient services in four out of five Danish regions. Here, we present a combined protocol paper and statistical analysis plan for the TEENS multi-site trial. The TEENS multi-site trial is an investigator-initiated, two-arm, parallel-group randomised clinical superiority trial with blinded outcome assessment. IERITA is provided as an add-on treatment to TAU and compared with TAU alone. IERITA is a therapist-guided, internet-delivered intervention for adolescents teaching emotion regulation skills and includes a complementary part for parents. Participants are randomly allocated in a 1:1 ratio, stratified by trial site and past-month NSSI episodes at baseline (1–10 compared to ≥11 episodes). The primary outcome is NSSI episodes within the past month measured by the Deliberate Self-Harm Inventory Youth version (DHSI-Y). Secondary outcomes include quality of life (KIDSCREEN-10), symptoms of depression, anxiety, and stress (DASS-21), and the proportion of participants with any past-month NSSI. Both primary and secondary outcomes are measured at the end of the intervention (12 weeks). Analyses will be conducted according to the intention-to-treat principle. This paper presents the design and statistical analysis plan for the TEENS multi-site trial. Publishing these considerations before inclusion of the last participant helps increase transparency and limit bias. The trial is approved by the Regional Ethics Committee in the Capital Region of Denmark (H-21035306; 1 February 2022, protocol version 1.3) and the Regional Data Protection Agency (P-2020-113; 8 September 2021). The trial is registered on ClinicalTrials.gov (identifier: NCT05179655; 5 January 2022).