Predictors of suicides occurring within suicide clusters in Australia, 2004-2008

A number of studies have investigated the presence of suicide clusters, but few have sought to identify risk and protective factors of a suicide occurring within a cluster. We aimed to identify socio-demographic and contextual characteristics of suicide clusters from national and regional analyses of suicide clusters. We searched the National Coroners Information System for all suicides in Australia from 2004 to 2008. Scan statistics were initially used to identify those deaths occurring within a spatial-temporal suicide cluster during the period. We then used logistic regression and generalized estimation equations to estimate the odds of each suicide occurring within a cluster differed by sex, age, marital status, employment status, Indigenous status, method of suicide and location. We identified 258 suicides out of 10,176 suicides during the period that we classified as being within a suicide cluster. When the deceased was Indigenous, living outside a capital city, or living in the northern part of Australia (in particular, Northern Territory, Queensland and Western Australia) then there was an increased likelihood of their death occurring within a suicide cluster. These findings suggest that suicide clustering might be linked with geographical and Indigenous factors, which supported sociological explanations of suicide clustering. This finding is significant for justifying resource allocation for tackling suicide clustering in particular areas.