Long-term outcome of early-onset compared to adult-onset schizophrenia: A nationwide Danish register study.

Objective: Early-onset schizophrenia (EOS) may have worse outcomes than adult-onset schizophrenia (AOS), but data are scarce. We compared outcomes of EOS vs. AOS.

Methods: Longitudinal, register-based study of patients diagnosed with schizophrenia in Denmark between 1996 and 2012, with follow-up until 12/2014. Co-primary outcomes were psychiatric inpatient days during the initial two years after schizophrenia diagnosis and mean number of annual inpatient days for the remaining follow-up.

Results: Altogether, 16,337 patients with schizophrenia were included (EOS = 1223, AOS = 15,114, mean follow-up = 9.5 ± 5.0 years). EOS were hospitalized longer during the first two years than AOS (180.9 ± 171.0 vs 163.4 ± 183.1 days, p < 0.005; IRR = 1.27, 95% CI = 1.19-1.35, p < 0.001), but duration and annual rates thereafter did not differ (EOS = 26.8 ± 57.1 days, AOS = 26.6 ± 56.2 days, p = 0.95; IRR = 1.07, 95% CI = 0.94-1.23, p = 0.30). Fewer EOS patients were never psychiatrically hospitalized (EOS = 17.2%, AOS = 20.1%, p < 0.001), but with no difference in re-admissions in patients diagnosed during hospitalization (EOS = 77.1% vs AOS = 78.1%, p = 0.56). More EOS patients were admitted involuntarily (41% vs. 36%, p < 0.02). AOS patients had more often comorbid substance use disorders during follow-up than EOS (EOS = 21.7%, AOS = 34.2%, p < 0.001). Substance use disorders and out-of-home placement were significantly associated with more inpatient days during both short- and long-term follow-up.

Conclusion: Although EOS was associated with more inpatient days in the first two years after diagnosis, results do not seem to support a generally poorer long-term outcome of EOS compared to AOS. Longer initial hospitalization may be driven by different treatment patterns in child and adolescent vs. adult psychiatry. These data suggest that patient characteristics other than age of onset significantly affect outcomes.