INTRODUCTION: Non-suicidal self-injury (NSSI) is considered a cathartic approach to reducing negative emotions
repeated occurrences increase the risk of suicide. Applying an information-knowledge-attitude-practice (IKAP) model might help patients establish effective and sustainable ways to express negative emotions and cope with difficulties, reducing NSSI. AIM: We explored an IKAP-based intervention on NSSI among adolescents and young adult patients with major depressive disorder (MDD). METHODS: A total of 120 adolescent and young adult patients with MDD who reported NSSI were recruited from January to December 2021. Using stratified randomisation, the participants were randomly divided into a balanced control group (usual treatment) and intervention group (IKAP intervention). The Cognitive Emotion Scale, NSSI, and handling of dangerous items were assessed pre- and post-intervention. RESULTS: Post-intervention, the intervention group had significantly lower NSSI, were more likely to give up dangerous items, and indicated better cognitive-emotional regulation than the control group (all p <
0.05). DISCUSSION: The IKAP model significantly improved NSSI-related outcomes. IMPLICATION FOR PRACTICE: The IKAP model could improve patients' cognitive-emotional regulation more than traditional health education, enabling patients to participate more actively in disease management, learn problem-solving skills, reduce negative emotions, actively cooperate with ward safety management practices, and reduce NSSI. TRIAL REGISTRATION: ChiCTR registration number: ChiCTR2100050317.