Mental Health Service Use Before First Diagnosis of a Psychotic Disorder.

Importance: Characterizing mental health service use trajectories preceding diagnosis of a psychotic disorder may help identify individuals at highest risk and in which settings they are at highest risk.

Objective: To examine mental health service use and diagnostic trajectories before first diagnosis of psychotic disorder and identify utilization and diagnostic patterns.

Design, setting, and participants: This population-based, retrospective cohort study used linked provincial health administrative data. The sample included individuals aged 15 to 29 years diagnosed with a psychotic disorder in Ontario, Canada, between April 1, 2012, and March 31, 2018. These individuals were matched to individuals with a diagnosis of a mood disorder. Data were analyzed from November 2018 to November 2019.

Main outcomes and measures: The main outcomes were rates, timing, and setting of mental health-related service use and associated diagnoses in the 3 years before the index disorder among individuals first diagnosed with a psychotic disorder compared with those first diagnosed with a mood disorder.

Results: A total of 10 501 individuals with a first diagnosis of psychotic disorder were identified (mean [SD] age, 21.55 [3.83] years; 72.1% male). A total of 72.2% of individuals had at least 1 mental health service visit during the 3 years before their first psychotic disorder diagnosis, which was significantly more than matched controls with a first mood disorder diagnosis (66.8%) (odds ratio [OR], 1.34; 95% CI, 1.26-1.42). Compared with individuals diagnosed with a mood disorder, individuals diagnosed with a psychotic disorder were significantly more likely to have had mental health-related hospital admissions (OR, 3.98; 95% CI, 3.43-4.62) and emergency department visits (OR, 2.27; 95% CI, 2.12-2.43) in the preceding 3 years. Those with psychotic disorders were more likely to have had prior diagnoses of substance use disorders (OR, 2.57; 95% CI, 2.35-2.81), other disorders (personality disorders, developmental disorders) (OR, 1.75; 95% CI, 1.61-1.90), and self-harm (OR, 1.64; 95% CI, 1.36-1.98) in the past 3 years compared with those diagnosed with mood disorders.

Conclusions and relevance: This study found that in the 3 years prior to an index diagnosis, individuals with a first diagnosis of psychotic disorder had higher rates of mental health service use, particularly emergency department visits and hospitalizations, compared with individuals with a first diagnosis of a mood disorder. Individuals with psychotic disorders also had a greater number of premorbid diagnoses. Differences in health service utilization patterns between those with a first psychotic disorder diagnosis vs a first mood disorder diagnosis suggest distinct premorbid trajectories that could be useful for next steps in prediction and prevention research.