Abstract
Background: Self-harm is a growing public health concern and the strongest predictor of suicide in young people (YP). The "Supporting Adolescents with Self-Harm" (SASH) intervention was developed with YP with lived experience and expert clinicians. It involves rapid follow-up after ED attendance and up to six intervention sessions. The intervention has three components: Therapeutic Assessment (TA) of self-harm; an enhanced safety plan (SP); and Solution-Focused Brief Therapy (SFBT). Depending on the YP's preference, carers can join sessions. Carers can also receive two individual sessions. The clinical and cost-effectiveness of SASH is being evaluated in a randomised controlled trial across nine emergency departments in three NHS Trusts in London, England. A total of 154 YP were recruited between May 2023 and March 2025 and randomised on a 1:1 ratio to SASH alongside Treatment As Usual (TAU) or TAU. A logic model describes the SASH inputs, activities, mechanisms, outcomes and longer-term impacts. The aim of this paper is to (1) illustrate how TA, SP, and SFBT were implemented in practice by presenting intervention materials and session recordings for four YP cases and one carer case and (2) explore how the case study materials/recordings reflect the intervention mechanisms in the SASH logic model. Methods: Each case focused on a different component of the intervention. Intervention materials (TA self-harm diagram and completed SP) and recorded SFBT sessions with four YP and one carer were analysed using a descriptive case study approach. The TA diagram and SP were extracted from medical records. Audio/video recordings of intervention sessions were identified. Recordings of intervention sessions and qualitative interviews were transcribed. Quotes from qualitative interviews with the same participants were included where relevant. Results: Across the four YP cases, some core themes emerged. The role of friendships for young people, particularly at school, was important in both negative and positive ways. Experiencing difficulties with friends at school led to feelings of sadness and stress, which could become overwhelming, leading to thoughts of self-harm ("I just need to hurt myself"), triggering self-harm behaviour. YP described mood changes and signs that they were becoming stressed, which improved their self-awareness and understanding of the link between their feelings and self-harm behaviour. They reflected on what kept them feeling calm and overcoming their fear of burdening others by sharing how they were feeling, as this helped them not to self-harm. They also described difficult feelings stemming from a need to please everyone or needing validation from others. Overcoming these feelings led to less social anxiety and more confidence. This made it easier to go to school and to be more social with friends/student peers, which in turn improved their mood. Conclusions: These case studies demonstrate how YP improved their self-awareness and understanding of the link between feelings and self-harm behaviour and identified personal strategies for managing difficult feelings and situations. The carer case study demonstrates how sessions with carers can facilitate carers better supporting their YP's mental health. Supporting YP and carers in this way has the potential to reduce the risk of future self-harm.