A population based elaboration of the role of age of onset on the course of schizophrenia

Background: Despite suggestions that an earlier age of onset and being male confer to a poorer course of schizophrenia, evidence regarding when these effects are most salient appears to be ambiguous. Aims: To examine the relationship of age of first hospitalization and sex with the course of hospitalization in a population based cohort. Method: All first admissions for schizophrenia in a national population based cohort in Israel from 1978 to 1992 were followed through 1996 (n = 12,071) using data from the National Psychiatric Hospitalization Case Registry of the State of Israel, a complete national registry of psychiatric admissions. Recursive partitioning was conducted to empirically determine cut-off points for age groups showing the greatest difference on the variables of interest. Results: A younger age of first hospital admission was associated with a greater likelihood of having more than one hospital admission, longer first admissions, more hospital admissions and more inpatient days per year. Of patients with age of first admission below 17, 82.5% had more than one admission which decreased for subsequent age groups to 73.54% (18-28), 69.36% (29-31), 62.88% (32-45), and 50.77% (over 45). Men had an earlier first admission than women, and had slightly more cut-off values. Irrespective of sex, the relationship between age at first admission and later hospitalization conformed to a linear trend. Conclusions: An earlier onset corresponds linearly with the severity of the course of illness and appears to have prognostic value.