The leading methods of suicide in Taiwan, 2002-2008

Restricting the methods of suicide has been proposed as one of the most effective suicide prevention strategies [1‐5]. As physical availability and socio-cultural acceptability are two important determinants in the choice of method [6], these factors would differ across geographic areas and therefore the leading methods of suicide would differ accordingly. Ajdacic-Gross et al. used mortality data from the World Health Organization to illustrate great variations in the preferred method of suicide across countries [7]. For example, poisoning by pesticides was common in some Asian countries (e.g., 38% of all suicides in Korea) and in Latin America (e.g., 86% in El Salvador, 61% in Nicaragua and 55% in Peru); poisoning by drugs was common in both Nordic countries (e.g., 18% in Finland and 14% in Demark) and the United Kingdom (15%); hanging was the preferred method of suicide in Eastern Europe (e.g., 92% in Lithuania, 85% in Latvia and 70% in Slovakia); as was suicide with firearms in the United States (61%) and jumping from a high place in cities and urban societies such as Hong Kong (43%) [7].

Ajdacic-Gross et al. further commented that the patterns of suicide typically change very slowly except for suicide by charcoal burning [7]. Suicide by charcoal burning has become epidemic in Hong Kong, Taiwan and Japan [8‐12]. In Taiwan, only 32 people completed suicide by charcoal burning in 1998 but this number increased to 1346 in 2005 [10]. A recent spatial and temporal analysis suggested that the epidemic of suicide by charcoal burning in Taiwan emerged more prominently in urban areas, was without a single point of origin, and rates remained highest in metropolitan regions over time [11].

Little is known about the differences in suicide rates by charcoal burning by geographic regions and cities/counties. This would have different implications for suicide prevention programs. For example, Taipei City and Kaohsiung City are the only two metropolitan areas in Taiwan and are classified at the same level of urbanization; however, Taipei City is in northern Taiwan and Kaohsiung City in southern Taiwan and the city governments were run by different political parties with many different local policies. City/county is the most important political administrative unit in Taiwan with its own budget and autonomy in designing locally relevant suicide prevention programs.

Cities/counties in Taiwan differ greatly in socio-demographic characteristics, ethnic composition, dialects used, economic structure and income level (Table 1). Taiwan experienced rapid economic growth during the 1970s and 1980s and this resulted in diverse development between cities/counties. For example, many high technology industries are located in northern Taiwan (such as Taipei County, Tauyuan County and Hsinchu County); and many counties (e.g., Nantou County, Yunlin County, Chiayi County, Pintung County, and Taitung County) rely predominantly on traditional industries and have a high percentage of agricultural population and lower disposable household income (Table 1). All seven cities are in urban areas with high population density. Most counties include some urban townships with high population density and some rural townships with low population density. General speaking, counties in the south and east have more rural townships and are poorer.

The diverse economic and social development between geographic regions and cities/counties has resulted in diverse physical availability and socio-cultural acceptability of certain methods of suicide. A previous study in Taiwan indicated that cities/counties with a higher percentage of agricultural population were more likely to have suicides from pesticides and cities/counties with a higher percentage of high buildings were more likely to have suicides from jumping [13]. We hypothesize that the leading method of suicide would be different across cities/counties and would have changed after the epidemic of suicide by charcoal burning.

For Taiwan as a whole, hanging was the leading method of suicide in both 2002-04 and 2006-08 and accounted for 30% of all suicides and deaths of undetermined intent. At the city/county level, hanging was the leading method in 18 out of 22 cities/counties in 2002-04 but decreased to 10 out of 22 cities/counties in 2006-08 (Table 2 and Figure 1). On the other hand, charcoal burning was not the leading method in any city/county in 2002-04 but increased to 10 out of 22 in 2006-08. Charcoal burning became the most commonly used method of suicide in 6 cities and 4 prosperous counties (i.e., Taipei County, Taoyuan County, Hsinchu County, and Taichung County) in 2006-08.

Table 3 shows the leading methods of suicide by city/county, sex and age between 2002-04 and 2006-08 in Taiwan. The sex-age groups whose leading method changed from 2002-04 to 2007-08 are highlighted. We found that the younger the age of the deceased, the more likely that the leading method would change from 2002-04 to 2006-08. Of 44 sex-city/county groups, 28 showed changes in the leading method for those aged 15-24. For the 25-44 age group, 18 showed changes as did 16 for the 45-64 group, and 13 for the ≧65 group. For females aged 15-24, the leading method of suicide was jumping in 9 cities/counties in 2002-04 but remained so in only one city (i.e., Taipei city) in 2006-08 as suicidal individuals in most cities/counties changed to charcoal burning.

The distribution of leading methods of suicide across cities/counties differed greatly by age group (Figure 2). In 2006-08, for 17 out of 22 cities/counties, charcoal burning was the leading method for those aged 15-24 and this number increased to 21 out of 22 cities/counties for 25-44 year olds. Hanging was still the most commonly used method for 45-64 year olds (18 out of 22) and ≧65 years olds (17 out of 22). Of elderly females who completed suicide in eastern Taiwan (i.e., Hualien County and Taitung County) more than half used pesticides to kill themselves.

Of 1651 suicides by pesticides occurred between 2006 and 2008, 541 (32.8%) cases used herbicides, 306 (18.5%) cases used insecticides, 38 (2.3%) cases used other pesticides, and 766 (46.4%) cases did not report specified type of pesticides. Parauqat was the most common used herbicides (471 cases) and organophosphates (130 cases) and methomyl (97 cases) were the two most often used insecticides in Taiwan.

Large variations in the distribution of leading methods of suicide across geographic regions and cities/counties in Taiwan were partially due to the different physical availability of particular methods such as pesticides and high buildings; however, great differences in patterns between age groups and across time within a given city/county (equal physical availability) were due mainly to differences and changes in the socio-cultural acceptability of certain methods (especially charcoal burning and pesticides). Suicide prevention programs at the city/county level should not only consider restricting the locally relevant, physically available methods of suicide, but should also consider addressing the false socio-cultural acceptability of certain methods of suicide by particular age groups.