BACKGROUND: Early intervention in youth mental health is essential, with up to 75% of mental health difficulties emerging before the age of 25. Over the past two decades, enhanced primary care models, such as Jigsaw in Ireland, have been developed to provide free, accessible, evidence-based mental health support for young people aged 12-25 years. Understanding trends in service utilisation and factors driving engagement is critical for service improvement.

OBJECTIVES: This study examines (1) trends in service utilisation within Jigsaw and (2) factors associated with session attendance, such as demographic, service-related, and contextual.

METHODS: Secondary analysis of routine clinical data was conducted, including 23 227 young people aged 12-25 who accessed Jigsaw services from 2017 to 2022. Time series analyses assessed trends in service utilisation, presenting issues, and wait times. Negative binomial regression models evaluated predictors of session count.

RESULTS: A steady increase in referrals was found over time, with clear seasonal fluctuations consistent with academic calendars. Early growth likely reflects service expansion, but the continued rise may suggest broader drivers. Anxiety was the strongest predictor of higher session utilisation across age groups (IRR = 1.13-1.15, p < 0.001).Higher baseline psychological distress predicted lower attendance in older youth but not in younger adolescents. Males attended fewer sessions than females. Small significant effects were observed for wait time (older > younger) and for season (summer/autumn > winter/spring). Parental referral predicted higher attendance in older youth.

CONCLUSIONS: Utilisation of primary care youth mental health services may be influenced by developmental, family, and contextual factors. Rising demand (with clear seasonal fluctuations) highlights the need for accessible, family-informed services and good integration with secondary care.