Point prevalence of schizophrenia in immigrant groups in Rotterdam: data from outpatient facilities

Reports of an increased incidence of schizophrenia in some immigrant groups to The Netherlands are based exclusively on hospital data.

1) to determine the treated point prevalence of schizophrenia at outpatient mental health services in Rotterdam and to compare the results for immigrants to those for natives; and 2) to compare groups born in The Netherlands and immigrant groups in terms of the proportions of patients with a previous hospital admission.

We included all patients aged between 20 and 64 who were treated for a non-affective psychosis at any of the outpatient mental health services in Rotterdam on October 1, 1994. The mental health professionals responsible reported on the socio-demographic and clinical characteristics of each patient.

Seven hundred and thirteen patients with a diagnosis of schizophrenia (DSM-III-R) were identified (rate: 2.1 per 1000). The (treated) prevalence of schizophrenia in male immigrants from Surinam and Morocco and in female immigrants from Surinam, the Netherlands Antilles and Cape Verde was significantly higher than that in their native-born counterparts (odds ratios between 2 and 3). The (treated) prevalence was not significantly higher in immigrants from Turkey, female immigrants from Morocco or male immigrants from the Antilles. Proportions of patients with a previous hospital admission were similar in each ethnic group (81-93%).

These findings are generally in line with earlier studies, based on the Dutch psychiatric registry, which has reported an increase in the (treated) incidence of schizophrenia in immigrants from Surinam and the Netherlands Antilles and in male immigrants from Morocco, and no increase in the (treated) incidence in immigrants from Turkey or female immigrants from Morocco.