Suicides in the Canton of Zurich (Switzerland)

QUESTIONS: The Swiss Health Observatory recently reported that the Canton of Zurich ranked fourth highest among the Swiss cantons in regard to suicide rates. The aim of this study was to identify sociodemographic risk factors (such as sex, age, marital status, religion and place of residence) in relation to suicide rates in the Canton of Zurich, and to explore suicide methods and co-morbidities from all suicides in this area between 1995 and 2007. METHOD: Data from Swiss statistics on causes of death were analysed using statistical modelling. RESULTS: Suicides were found to be more frequent among men than women, and suicide was more prevalent in older or single people than in younger or married people, respectively. Age groups over 70 had increasingly high suicide rates compared to lower age groups. Investigating geographical distribution, highest suicide risks were found in the cities and high-income municipalities. The chosen suicide methods differed among age and sex groups. Poisoning was more than twice as frequent among women, and more common with increasing age in both sexes. Usage of firearms was about ten times as frequent among men. For train suicides, the age group of 10 to 19 years predominated. In 36% of suicide cases, mental disorders were listed as co-morbidities; in 12% malignant tumours were reported. CONCLUSIONS: Relatively low rates of mental illness were reported in older suicide victims, despite a massively rising suicide rate with increase of age, indicating that undiagnosed depression could contribute to the high suicide rates in the elderly. Demographic changes in the coming years may result in larger numbers of suicides.