First contact incidence of psychotic disorders among native Dutch and Moroccan immigrants in the Netherlands: Influence of diagnostic bias

Background: Several studies have reported increased incidence rates of psychotic disorders among immigrant groups. Surprisingly, the cross-cultural validity of the diagnostic instruments that were used was never tested. Aims: To examine whether the incidence rates of psychotic disorders including schizophrenia among Moroccan immigrants to the Netherlands remain increased when a cultural sensitive diagnostic interview is used. Method: We compared first contact incidence with a standard and a cultural sensitive version of a diagnostic interview. Results: Age and gender adjusted relative risk for psychotic disorders and schizophrenia among Moroccans compared to native Dutch was 7.9 (95% CI 4.7-13.5) and 7.8 (95% CI 4.0-15.2) respectively based on the standard diagnostic interview and 4.2 (95% CI 2.3-7.9) and 1.5 (0.5-4.3) respectively based on the cultural sensitive version the diagnostic interview. Conclusion: First contact incidence of schizophrenia among Moroccans was no longer significantly higher than among ethnic Dutch people when a cultural sensitive diagnostic procedure was applied.