Incidence of treated first episode psychosis from an Australian early intervention service and its association with neighbourhood characteristics.

Objectives: Psychotic disorder incidence varies geographically and is associated with neighbourhood characteristics, including social deprivation, population density, unemployment, social capital or social fragmentation. Yet it is not known whether these findings are applicable to Australia's unique geography. This study aimed to determine whether the incidence of first episode psychosis (FEP) varies according to neighbourhood characteristics in an Australian cohort.

Method: This study included all young people, aged 15 to 24, with an FEP who attended Orygen Youth Health in Melbourne, from a geographically defined catchment area encompassing Northern and Western Melbourne, over a 44-month period. Neighbourhood demographic data was collected from the 2011 Australian National Census. Negative binomial regression was used to determine incidence rate ratios controlled for age, sex and migrant status.

Results: A total of 747 young people had an FEP during the 44-month study period and 722 were included in this study. Of these, 58.0% were males and 67.9% had a non-affective psychotic disorder; the mean age of the cohort was 19.1 years. The incidence of FEP in young people aged 15 to 24 in the catchment area was 123.2 per 100,000 person-years. There was a higher incidence of FEP in neighbourhoods of greatest social deprivation (IRR = 1.65, CI = 1.06-2.51, p = .02), highest unemployment (IRR = 1.56, CI = 1.04-2.35, p = .03) and above average social fragmentation (IRR = 1.42, CI = 1.02-1.97, p = .04), when controlled for age, sex and migrant status.

Conclusions: This study highlights variation in psychotic disorder incidence and the need for this disparity to be reflected in appropriate resource allocation.