Te Rau Hinengaro: The New Zealand Mental Health Survey: Overview of methods and findings

Objective: To estimate the prevalence and severity of anxiety, mood, substance and eating disorders in New Zealand, and associated disability and treatment. Method: A nationwide face-to-face household survey of residents aged 16 years and over was undertaken between 2003 and 2004. Lay interviewers administered a computerized fully structured diagnostic interview, the World Health Organization World Mental Health Survey Initiative version of the Composite International Diagnostic Interview. Oversampling doubled the number of Maori and quadrupled the number of Pacific people. The outcomes reported are demographics, period prevalences, 12 month severity and correlates of disorder, and contact with the health sector, within the past 12 months. Results: The response rate was 73.3%. There were 12 992 participants (2595 Maori and 2236 Pacific people). Period prevalences were as follows: 39.5% had met criteria for a DSM-IV mental disorder at any time in their life before interview, 20.7% had experienced disorder within the past 12 months and 11.6% within the past month. In the past 12 months, 4.7% of the population experienced serious disorder, 9.4% moderate disorder and 6.6% mild disorder. A visit for mental health problems was made to the health-care sector in the past 12 months by 58.0% of those with serious disorder, 36.5% with moderate disorder, 18.5% with mild disorder and 5.7% of those not diagnosed with a disorder. The prevalence of disorder and of serious disorder was higher for younger people and people with less education or lower household income. In contrast, these correlates had little relationship to treatment contact, after adjustment for severity. Compared with the composite Others group, Maori and Pacific people had higher prevalences of disorder, unadjusted for sociodemographic correlates, and were less likely to make treatment contact, in relation to need. Conclusions: Mental disorder is common in N ew Zealand. Many people with current disorder are not receiving treatment, even among those with serious disorder.