Mental health-related hospitalisations associated with patterns of child protection and youth justice involvement during adolescence: A retrospective cohort study using linked administrative data from the Northern Territory of Australia

•The risk of mental health hospitalisations in adolescence increases with child protection and youth justice involvement.•Out-of-home care (OOHC) and detention were linked to the highest risk of mental health hospitalisations.•A higher frequency of mental-health hospitalisations was associated with OOHC during adolescence.•Trauma-informed approaches and co-ordination of services between child protection and youth justice systems are needed.•The over-representation of Aboriginal adolescents in this study reinforces the need for culturally responsive approaches.