Divergent trends in suicide by socio-economic status in Australia

Abstract

This study investigated secular trends in socio-economic status (SES) differentials in Australian suicide (1979-2003), which includes overall declines in male suicide from 1998. Suicide rates were stratified by approximate equal-population quintiles of area-based SES for the period 1979-2003 and examined across five quinquennia, centred on each Australian Census from 1981 to 2001, to determine if (1) SES differentials in suicide have persisted over time, and (2) if SES differentials have widened or narrowed. Suicide rates (per 100,000) were adjusted for confounding by sex, age, country-of-birth, and urban-rural residence using Poisson regression models, and secular changes in SES differentials were assessed using trend tests on suicide rate ratios (low to high SES quintiles). Socio-economic status (SES) differentials persisted across the study period for both males and females after adjusting for the effects of age, migrant status, and urban-rural residence, with the largest differences between low and high SES groups evident in males, and especially young males (20-34 years). For males, suicide rates increased significantly in all SES groups until 1998, before diverging significantly in the most recent 5-year period, particularly in younger males (P<0.0001). In young males, suicide rates in the most recent period increased in the low SES group from 44.8 in 1994-1998 to 48.6 in 1999-2003 (an 8% increase). In contrast, suicide rates in the middle SES group decreased from a peak of 37.3 to 33.5 (a 10% decrease), and in the high SES group from a peak of 33.0 to 27.9 (a 15% decrease). A similar statistically significant divergence of a lesser magnitude was also evident in all age males and younger females (20-34 years). This study shows that SES differentials in suicide persisted in Australia for most of the period 1979-2004. The decline in suicide in young males in the most recent quinquennium was limited to middle and high SES groups, while the low SES group displayed a continued increase. The continued increase in suicide in low SES males has implications for social and economic intervention and suicide control programs.