Profiling of subjective rewarding experiences immediately after NSSI in a clinical sample of adolescents using k-means clustering: an exploratory study

Adolescents with nonsuicidal self-injury (NSSI) often report rewarding experiences, including ‘feeling better’ and ‘eliciting care from others’ following self-injury. These subjective rewarding experiences may reinforce self-injurious behavior and be associated with psychosocial dysfunction. Various theoretical models explain the motivation behind NSSI; nevertheless, research focused on experiences immediately after NSSI is limited. In an exploratory framework, 132 clinical adolescents with NSSI (87.9% girls; mean age 15.1) were assessed to determine subjective rewarding experiences immediately after most recent episode of NSSI using the Suicide Attempt Self-Injury Interview (SASII). Participants also completed psychological questionnaires and provided basic demographic and clinical information. A k-means clustering analysis was used to classify participants into subgroups based on subjective rewarding experiences, determining the optimal k using the silhouette method. Subsequently, subgroup differences in basic demographic, clinical, and psychological factors were examined. Two clusters were identified using k-means clustering based on the level of subjective rewarding experiences following NSSI. Adolescents in cluster 1 (62.9%) reported lower levels of rewarding experiences associated with NSSI than did those in cluster 2 (37.1%), but showed greater levels of externalizing problems. Compared with cluster 1, cluster 2 had higher rates of depressive symptoms, stressful life events, and receiving medical treatment. This study identified adolescents who are vulnerable to the rewards inherent in NSSI. The identified subgroups differ in subjective rewarding experiences, suggesting that adolescents in each cluster may benefit from different therapeutic approaches tailored to their situation.