Influences of population-level factors on suicides in older adults: a national ecological study from Australia

Objective: The relationship between older adult suicide rates and population-level variables has been examined in a few studies. Therefore, the objective of the present study is to analyse the extent to which population-level factors are associated with suicide by older persons in Australia, from an ecological perspective.

Methods: Suicide rates for older adults aged 65 years and over were calculated for 68 observation units at Statistical Areas Level 4 in Australia for 2002-2011. The 2011 Census of Population and Housing was used for population-level variables. Analysis on standardised suicide mortality ratios and Poisson regression were performed to examine geographical and gender differences.

Results: Between 2002 and 2011, a total of 3133 suicides of persons aged 65 years and above (men: n = 2418, 77.1%) was identified with an average annual rate of 10.1 per 100,000 persons. Suicide rates in older adults vary widely between different geographical regions in Australia. The multivariate estimates of contextual factors showed that the risk of suicide was positively associated with the sex ratio (incidence risk ratio (IRR) = 1.053, 95%CI = 1.016-1.092), the proportion of those in tenant household (IRR = 1.120, 95%CI = 1.081-1.160) and Australian residents born in North-West Europe (IRR = 1.058, 95%CI = 1.022-1.095). Significant gender variations were found.

Conclusions: Specific factors increasing risk of suicide for older adults on SA4 level in Australia were living in areas with a higher proportion of male population, a higher proportion of tenant household dwellers and a higher proportion of immigrants from North-West Europe. The different influences of population-level factor on suicide between older men and women indicate the need for targeted suicide prevention activities.