RESUMO
INTRODUCTION: In Mexico, as in other countries, studies do not distinguish between attempted suicide and suicidal and nonsuicidal self-injury (NSSI). The aim of this study was to investigate self-injury and its prevalence using several definitions, in addition to studying the frequency of the proposed DSM-5 criteria for NSSI in adolescent girls and boys. METHODOLOGY: The study was observational, descriptive, cross-sectional, and comparative using a nonrandomized sample of adolescent girls and boys from official high schools who completed the self-injury questionnaire. RESULTS: The participants were 533 older children and adolescents with a mean (SD) age of 13.37 (0.95) years, age range 11 to 17 years, and 54% female sex distribution. The prevalence of NSSI defined according to proposed DSM-5 criteria was 5.6% (N=30) and, according to a broad definition using only item 51 ("Do you hurt yourself without intending to end your life?"), 17.1% (N=140). Prevalence defined by the number of events in the last month (1-3 events) was 9.9% (N=53), in the last 6 months (1-3 events), 11.6% (N=62), and in the last year (5 events), 12.6% (N=67). The age at onset was 11.9 (1.39) years (range 6-15 years). Most DSM-5 criteria were more frequent in girls than boys. CONCLUSIONS: Suicidal and nonsuicidal self-injury are frequent in the community. Important points for decision-making in schools and medical practice are discussed.