Latent trajectories of mental health service use in an Australian state population cohort of children

Objectives: Mental health service use among young people is increasing, and small groups within the population disproportionately account for the majority of mental health service use. The aims of this study were to identify population-based trajectories of mental health service use across childhood and adolescence and associated sociodemographic/other risk factors. Methods: Mental health trajectories between birth and 17 years of age were identified using zero-inflated Poisson latent-class growth mixture modelling, in a New South Wales cohort of 9510 children (born between 2002 and 2005) who had at least one primary diagnosis of a mental disorder recorded in ‘Emergency Department’, ‘Admitted Patients’ and/or ‘Mental Health Ambulatory’ data collections. Results: A two-trajectory solution provided the optimal fit to the data: One trajectory displayed high increasing service use (n = 1861, 19.6%) and accounting for more than 68% of the days treated for mental disorder among the entire cohort. The other trajectory (n = 7649, 80.4%) was distinguished by a consistently low level of service use. Membership in the high mental health service use trajectory was associated with parental mental disorder, child maltreatment exposure and diagnoses of psychosis spectrum and personality disorders. Conclusion: Less than one-fifth of children account for more than 68% of hospital and ambulatory services used up to age 17 years; these children are more likely to have parents with mental disorder and to have been exposed to child maltreatment, pointing towards multi-disciplinary supports as a basis for early intervention.