Evolution of first episode psychosis diagnoses and health service use among young Māori and non-Māori-A New Zealand national cohort study.

Abstract

The validity of diagnostic classification in early psychosis has important implications for early intervention; however, it is unknown if previously found disparities between Māori (Indigenous people of New Zealand) and non-Māori in first episode diagnoses persist over time, or how these differences impact service use. We used anonymized routine mental health service data and a previously established cohort of over 2400 13-25-year-old youth diagnosed with FEP between 2009 and 2012, to explore differences in diagnostic stability of psychosis diagnoses, comorbid (non-psychosis) diagnoses, and mental health service contacts between Māori and non-Māori in the five-year period following diagnosis. Differences in schizophrenia and affective psychosis diagnoses between Māori and non-Māori were maintained in the five-year period, with Māori being more likely to be diagnosed with schizophrenia (51% vs. 35%), and non-Māori with bipolar disorder (28% vs. 18%). Stability of diagnosis was similar (schizophrenia 75% Māori vs. 67% non-Maori; bipolar disorder 55% Māori vs. 48% non-Māori) and those with no stable diagnosis at FEP were most likely to move towards a schizophrenia disorder diagnosis in both groups. Māori had a lower rate of diagnosed co-morbid affective and anxiety symptoms and higher rates of continued face to face contact and inpatient admission across all diagnoses. Indigenous differences in schizophrenia and affective psychosis diagnoses could be related to differential exposure to socio-environmental risk or assessor bias. The lower rate of co-morbid affective and anxiety disorders indicates a potential under-appreciation of affective symptoms in Māori youth with first episode psychosis.