Long-term effects of psychotherapy in children and adolescents: protocol for database development and a systematic review in the LaKiJu META project

INTRODUCTION: Approximately one in every six children and adolescents is affected by mental disorders, which impose significant costs on patients, their families and societies. Psychotherapy is the first-line treatment for many of these disorders, and systematic reviews of post-intervention effects show small to moderate favourable outcomes compared with control groups. However, the long-term effects of psychotherapy remain less well understood.