PT - JOURNAL ARTICLE AU - Kristin Cleverley AU - Kathryn J Bennett AU - Sarah Brennenstuhl AU - Amy Cheung AU - Joanna Henderson AU - Daphne J Korczak AU - Paul Kurdyak AU - Andrea Levinson AU - Antonio Pignatiello AU - Jennifer Stinson AU - Aristotle N Voineskos AU - Peter Szatmari TI - Longitudinal Youth in Transition Study (LYiTS): protocol for a multicentre prospective cohort study of youth transitioning out of child and adolescent mental health services at age 18 AID - 10.1136/bmjopen-2019-035744 DP - 2020 Feb 01 TA - BMJ Open PG - e035744 VI - 10 IP - 2 4099 - http://bmjopen.bmj.com/content/10/2/e035744.short 4100 - http://bmjopen.bmj.com/content/10/2/e035744.full SO - BMJ Open2020 Feb 01; 10 AB - Introduction Transition between health services is widely recognised as a problematic hurdle. Yet, the factors necessary for successful transition out of child and adolescent mental health services (CAMHS) as youth reach the service boundary at age 18 are poorly understood. Further, fragmentation and variability among the services provided by mental health organisations serve to exacerbate mental illness and create unnecessary challenges for youth and their families. The primary aim of the Longitudinal Youth in Transition Study (LYiTS) is to describe and model changes in psychiatric symptoms, functioning and health service utilisation at the transition out of CAMHS at age 18 and to identify key elements of the transition process that are amendable to interventions aimed at ensuring continuity of care.Methods and analysis A prospective longitudinal cohort study will be conducted to examine the association between psychiatric symptoms, functioning and mental health and health service use of youth aged 16–18 as they transition out of child mental health services at age 18. We will recruit a sample of (n=350) participants from child and adolescent psychiatric programmes at two hospital and two community mental health sites and conduct assessments annually for 3 years using standardised measures of psychiatric symptoms, functioning and health service utilisation.Ethics and dissemination Ethics approval has been obtained at all four recruitment sites. We will disseminate the results through conferences, open access publications and webinars.