The longitudinal course of childhood bullying victimization and associations with self‐injurious thoughts and behaviors in children and young people: A systematic review of the literature

INTRODUCTION: Bullying victimization has consistently been highlighted as a risk factor for self‐injurious thoughts and behaviors (SITBs) in young people. This systematic review of prospective, community‐based studies explored associations between bullying victimization (traditional/face‐to‐face and cyber) across the full spectrum of self‐harm and suicidality, in children and young people aged up to (and including) 25 years. Importantly, associations by sex/gender were explored. METHODS: MEDLINE, Embase, PsycINFO, CINAHL and Scopus were searched for articles meeting the inclusion criteria. Articles were screened by title, abstract and full text. Quality appraisal was performed using the Newcastle‐Ottawa Scale for cohort studies. Data were synthesized narratively. The protocol is registered on PROSPERO (CRD42021261916) and followed PRISMA 2020 guidelines. RESULTS: A total of 35 papers were included, across 17 countries. Results were presented by bullying type: traditional/face‐to‐face (n = 25), cyber (n = 7) and/or an aggregate of both types (n = 7). Outcomes included suicidal ideation (n = 17), self‐harm (n = 10), suicide attempt (n = 4), NSSI (n = 4), other (n = 7). Studies measured outcomes in under 18s (n = 24), 18–25‐year‐olds (n = 8) and both under 18s and 18–25‐year‐olds (n = 3). Studies exploring the role of sex/gender (20%) found some interesting nuances. CONCLUSIONS: Some weak to strong associations between bullying and SITBs were found yet conclusions are tentative due to study heterogeneity (e.g., methods used, conceptualizations and operationalisations of exposures/outcomes). Future research should address methodological issues raised in this review, and further explore gender differences in bullying, including by bullying sub‐types (e.g., overt or relational) and victim status (e.g., victim or bully‐victim).