BACKGROUND: The prevalence of mental ill health is increasing in young people worldwide, with rising referrals to child and adolescent mental health services (CAMHS). The numbers and proportions of the youth population who present to CAMHS, however, including how those figures are changing over time, are unclear. Understanding trends in mental health service contacts for young people over time is crucial mental health surveillance data.

AIMS: Our aim was to calculate both the lifetime and annual prevalence of CAMHS contact in Wales for young people up to age 18 years.

METHOD: Using linked Welsh administrative healthcare records, we calculated the annual prevalence of CAMHS contacts between 2004 and 2023. We also calculated the lifetime prevalence of CAMHS contacts for sequential annual birth cohorts born between 1991 and 2005 and followed to age 18 (between 2009 and 2023).

RESULTS: In 2004, 0.8% ( = 4665) of the total child and adolescent population were in contact with CAMHS. By 2022, this had risen nearly five-fold to 3.9% ( = 19 870) of the total child and adolescent population. Among the 1991 birth cohort who turned 18 in 2009, 5.8% had contact with CAMHS at some stage in childhood or adolescence. For individuals born in 2005 who turned 18 in 2023, this figure had risen to 20.2%.

CONCLUSIONS: The number of the young people in contact with CAMHS has increased dramatically over the past 15 years, from 1 in 17 young people who turned 18 in 2009 to 1 in 5 young people who turned 18 in 2023.