CAOS contribution to understanding cultural/ethnic differences in the prevalence of bipolar affective disorder in New Zealand.

Objective: To examine whether data on the clinical profiles of psychiatric service users can inform the claim that Māori in the New Zealand community have an increased rate of bipolar disorder.

Method: The standardized recordings of a variety of clinical phenomena previously collected in a New Zealand study of psychiatric service users was extracted for those persons who were diagnosed with a bipolar mental disorder. The individual clinical phenomena were then compared by ethnicity.

Results: The most dramatic result was the increased recording of high levels of overactivity or disruptive aggressive behaviour in Māori compared with European in psychiatric service users, despite which, the rates of the disorder did not significantly differ by ethnicity.

Conclusion: In the community survey lay raters were deciding on the presence or absence of phenomena including hyperactivity without the contextual knowledge that clinicians use. It is possible that the Composite International Diagnostic Interview decision tree was being fed an excessive amount of that criterion.