Introduction Many patients exhibit subsyndromal clinical findings of schizophrenia prior to diagnosis. Early treatment may mitigate schizophrenia development, yet little is known about comorbidities and healthcare resource utilization (HCRU) in these patients before diagnosis. Methods This retrospective, longitudinal cohort study, conducted between January 1, 2007 and April 30, 2016, used claims data from the US HealthCore Integrated Research Database. Newly diagnosed patients with schizophrenia (International Classification of Diseases, Ninth Revision: 295.x or ICD 10 F20.%) were identified and matched (1:4) with non-schizophrenia comparators. Patients were 15–54 years of age with either ≥1 inpatient/emergency room claim with a primary schizophrenia diagnosis, or ≥2 claims in any setting with any schizophrenia diagnosis. Demographics, comorbidities, physician specialties, medications, and related services, and other HCRU were compared between cohorts for up to 5 years before diagnosis. Results The schizophrenia cohort included 6732 patients (57.4% male, mean age 30.3 years for males and 36.2 years for females). All outcomes were more prevalent in the schizophrenia cohort than the comparator cohort. Substantial comorbidity, medication use, and HCRU were observed in the schizophrenia cohort even 4–5 years before diagnosis with increasing findings approaching diagnosis. From 4–5 years to 0–12 months before diagnosis, resource use increased from 20.5% to 53.3% for atypical antipsychotics, 29.3% to 48.2% for antidepressants, and 15.1% to 35.5% for psychiatric diagnostic examinations. Conclusions Patients with schizophrenia extensively use healthcare resources up to 5 years before diagnosis. Our findings may help with developing predictive models to identify patients at high risk of schizophrenia.
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