Bullying victimisation and perpetration and the association with mental disorders among adolescents in Kenya, Indonesia, and Vietnam: Findings from the National Adolescent Mental Health Surveys

Background: Few studies report the prevalence of both bullying victimisation and perpetration at the national level in low- and middle-income countries, with fewer still reporting the association with mental disorders assessed diagnostically. Methods: Nationally representative household surveys of adolescents aged 10-17 years and their primary caregiver were conducted in Kenya, Indonesia, and Vietnam as part of the National Adolescent Mental Health Surveys (NAMHS). Adolescents were asked about bullying victimisation and perpetration in the past three months. The prevalence of mental disorders in the past 12 months was assessed using a diagnostic instrument. The prevalence of bullying involvement was calculated, along with bullying victimisation and perpetration which were further disaggregated by sex and age. Types of victimisation and perpetration were assessed among those who endorsed bullying involvement. Adjusted odds ratios quantified the association between any mental disorder and bullying victimisation and perpetration. All findings were weighted to the respective countrys population and presented with 95 confidence intervals (CIs). Results: The prevalence of any bullying involvement was highest in Kenya (6.3, CI 5.3-7.4), followed by Indonesia (3.4, 95 CI 2.4-4.8), then Vietnam (1.9, 95 CI 1.3-2.7). For bullying victimisation, both Kenya (4.1, 95 CI 3.4-5.0) and Indonesia (2.6, 95 CI 1.9-3.6) had significantly higher prevalence than Vietnam (1.2, 95 CI 0.9-1.67). Kenya had significantly higher prevalence of bullying perpetration (3.1, 95 CI 2.5-3.8) compared to Indonesia (1.1, 95 CI 0.6-2.1) and Vietnam (0.8, 95 CI 0.5-1.2). Adolescents experiencing bullying victimisation were significantly more likely to have a mental disorder than those who had not been bullied in all three countries (Kenya: aOR 2.17, 95 CI 1.50-3.15; Indonesia: aOR 3.55, 95 CI 1.47-8.59; Vietnam: aOR 4.71, 95 CI 1.82-12.21). The same was seen for bullying perpetration although only in Kenya (aOR 4.38, 95 CI 2.77-6.93) and Indonesia (aOR 4.32, 95 CI 1.62-11.51). Conclusions: NAMHS is the first study to report national prevalence estimates of bullying victimisation and perpetration among adolescents in Kenya, Indonesia, and Vietnam. Bullying was strongly associated with adolescent mental disorders and is consequently an important consideration for strategies aimed at improving adolescent mental health.© The Author(s) 2025.