Australian suicide trends 1964-1997: youth and beyond?

We present suicide rates and trends across all ages, placing them in context by comparing them with rates from other Western nations. The national focus on youth suicide to the relative exclusion of older age groups is examined in the light of these data.

Years of potential life lost (YPLL) were calculated for 10-year age and sex groups for the most recent year (1997). The formula used was adapted from that used by the Australian Bureau of Statistics⁴ in order to incorporate age groups (Box 1). The Australian population at 30 June 1991 was chosen as the standard population, as suggested by the Australian Bureau of Statistics.

International data were obtained from the World Health Organization (WHO)^5-8 and Lester and Yang.⁹ Mean suicide rates were calculated for 23 Western countries (including Australia), averaged over 1990-1994, for 10-year age and sex groups. These 10-year age and sex rates were then ranked to compare Australia with other nations.

Males

Years of potential life lost by suicide in 1997 are shown in Box 2.

Boxes 3a and 3b list the mean suicide rates (per 100 000 population) by age group and sex for 23 Western nations, including Australia.

From a policy perspective, the most important finding is that suicide rate increases since 1973 for men aged 25-34 years have paralleled those of 15-24 year olds, with even less evidence of a recent plateau. Despite having shorter life expectancies, the toll in potential years of life lost (in 1997) was greatest for 25-34 year olds. These years are also the peak years for early parenthood, making the likelihood of there being bereaved offspring greater than in the younger group. These findings suggest that priority initiatives for youth suicide prevention should be extended to those aged 15-34 years, if not further (the high level of potential years of life lost continues to 44 years). The Federal Government's recently announced National Suicide Prevention Policy provides for ages beyond youth, by recognising that rising rates are not confined to the age group 15-24 years and that high suicide rates in the elderly should not be overlooked.

It is unclear whether or to what extent the suicide phenomenon in boys and young men might be a cohort effect -- a "damaged" generation. The later commencement of the rise in suicide rate in men aged 25-34 years and the, as yet, absence in this age group of the possible 1990s plateau could be seen as consistent with this.

Rates in females aged 15-24 years showed no convincing rise. It has previously been noted that suicide rates in females aged 15-19 years rose modestly between 1960 and 1989, while rates for those aged 20-24 years showed no overall change over this period.¹⁰ However, much of the rise in females aged 15-19 years was in the early 1960s, predating the rise in rates of 15-19-year-old males, but coinciding with a general, transient rise in suicide rates in females of all ages. Perhaps the most important observation regarding young females in the present study is that their suicide rates remained relatively static at a time when rates for most other female age groups declined.

Suicide rates in children under 15 years of age have not significantly altered over time, although the small numbers involved do not lend confidence to rate estimates. The recording of suicide in children under the age of 10 years is affected by the different criteria used by the Australian Bureau of Statistics for determining suicide: it is considered that children have a limited ability to form an intent to suicide. Hence, more explicit evidence of suicidal intent is required,¹¹ usually a coroner having stated explicitly that suicide was the cause of death. As most State and Territory Coroners' Acts discourage if not prohibit such findings (for all ages), such explicit statements are unlikely.¹¹

Beyond 35 years in women, and 45 years in men, and up to 75 years and over for both sexes, Australian suicide trends are striking. In both sexes there have been major declines, and for much of the period these declining male and female rates have been parallel, quite unlike the trends for 15-24 year olds. It is unclear whether these declining rates have as yet plateaued. Even if this were not the case, it is inevitable that these declining rates will shortly level out and increase again (from the trends over the complete period a number of these age rates would reach zero in the early decades of the next century). In the early 1960s, suicide rates, particularly in women and in older age groups, rose in association with an epidemic of barbiturate poisoning, subsequently to fall in the late 1960s, reaching rates in the early 1970s similar to those before this epidemic.^12,13 The causal factors determining the subsequent decline in rates of those between 35 and 74 years are yet to be determined. It is possible that such determination might yield valuable clues as to the causes and possible methods of preventing suicide in young people.

International comparisons should be interpreted conservatively, as variations in data collection systems will account for some of the variations. With these reservations in mind, among 23 Western nations, Australian suicide rates for 15-24 year olds ranked fourth for males and eighth for females (Boxes 3a and 3b). Australian rates for both sexes between the ages of 35 and 74 years, as well as declining, compared favourably internationally (ranking in the middle of or below those of other Western nations).

Although Australian suicide rates for those over 75 years were not declining, they nevertheless again compared favourably from an international perspective. Whereas the Australian suicide rate for 15-24-year-old males was over half that of the highest-placed nation (Finland), the corresponding ratio for males 75 years and over was about one-sixth. For females, these comparisons were even more marked. Nevertheless, a comprehensive policy should not overlook the needs of men over 75 years, especially as, in Australia, suicide rates in this age group surpass those of all other age groups.

The Western nations with lower suicide rates include those that provided most of the early immigrants to Australia: Greece, Italy (except in the elderly), the United Kingdom and Ireland. The highest suicide rates were in mainland Western Europe (especially Hungary) and Scandinavia (especially Finland). Some of these nations, for example Denmark, have profiles radically different from that of Australia, with lower youth suicide rates but much higher rates in those over 35 years of age.

Canada and, to a lesser extent, the United States and New Zealand are the nations with suicide rate profiles most similar to Australia's. All four of these nations have common characteristics of European migration, a comparatively short history (apart from their indigenous populations), geographical isolation, climatic extremes and more.¹⁰ They serve as potentially valuable nations to study shared characteristics that may affect suicide rates.

Studies have yet to provide explanations for these similarities and differences which have often been overlooked, largely as a consequence of the worldwide lack of epidemiological mental health data. While differences in prevalence of psychiatric disorders are potentially relevant, the magnitude of the different international rates suggests other factors may operate. Hungary and Finland share common cultural origins and high suicide rates. It has been suggested that Finland's high suicide rates in young men may relate to cultural expectations that men should be tough and resilient¹⁴ -- a suggestion that might be equally relevant in Australia, New Zealand, the United States and Canada. It is possible that a better understanding of cultural influences and how to positively modify them might be relevant to suicide prevention.

1. Commonwealth Department of Health and Family Services. Youth suicide in Australia: a background monograph. 2nd edition. Canberra: AGPS, 1997.
2. Snowdon J. Suicide rates and methods in different age groups: Australian data and perceptions. Int J Geriat Psychiatry 1997; 12: 253-258.
3. Hassan R, Carr J. Changing patterns of suicide in Australia. Aust N Z J Psychiatry 1989; 23: 226-234.
4. Australian Bureau of Statistics. Causes of death, Australia, 1996: 73. (Catalogue No. 3303.0.)
5. World Health Organization. World Health Statistics Annual 1992. Geneva: WHO, 1993.
6. World Health Organization. World Health Statistics Annual 1993. Geneva: WHO, 1994.
7. World Health Organization. World Health Statistics Annual 1994. Geneva: WHO, 1995.
8. World Health Organization. World Health Statistics Annual 1995. Geneva: WHO, 1996.
9. Lester D, Yang B. Suicide and homicide in the twentieth century: Changes over time. Commack, NY: Nova Science, 1998: 165-204.
10. Cantor CH, Leenaars AA, Lester D, et al. Suicide trends in eight predominantly English-speaking countries 1960-1989. Soc Psychiatry Psychiatr Epidemiol 1996; 31: 364-373.
11. Cantor CH, Neulinger K, Roth J, Spinks D. The epidemiology of suicide and attempted suicide among young Australians: a report to the National Health and Medical Research Council: Australian Institute for Suicide Research and Prevention. In press.
12. Oliver G, Hetzel BS. An analysis of recent trends in suicide rates in Australia. Int J Epidemiol 1973; 2: 91-101.
13. Whitlock FA. Suicide in Brisbane, 1956-1973: The drug-death epidemic. Med J Aust 1975; 1: 737-743.
14. Retterstol N. Suicide in the Nordic countries. Psychopathology 1992; 25: 254-265.

Reprints will not be available from the authors.
Correspondence: Dr C H Cantor, Australian Institute for Suicide Research and Prevention, Griffith University, Nathan, QLD 4111.
Email: C.CantorATmailbox.gu.edu.au