Incidence of early onset schizophrenia
diagnosis from ICD-8 to ICD-10. (ii) All reported
incidences are solely diagnosed incidences, thus
individuals without contact to the psychiatric
system were not included. Schizophrenia is a severe
mental illness, which is most often cared for in an
inpatient hospital setting, but patients diagnosed
solely as outpatients before 1995, are not in the
register. (iii) In calculating IR, we used the number
of persons in each age group for each time period as a
proxy of person-time, as data on date of diagnosis
and date of birthday were unavailable.