The authors have declared that no competing interests exist.
Conceived and designed the experiments: SSC YYC PSFY WJL AH DG. Performed the experiments: SSC YYC PSFY WJL AH DG. Analyzed the data: SSC PSFY. Contributed reagents/materials/analysis tools: SSC YYC PSFY DG. Wrote the first draft of the manuscript: SSC YYC. Contributed to the writing of the manuscript: SSC YYC PSFY WJL AH DG.
Using a time trend analysis, Ying-Yeh Chen and colleagues examine the evidence for regional increases in charcoal-burning suicide rates in East and Southeast Asia from 1995 to 2011.
Suicides by carbon monoxide poisoning resulting from burning barbecue charcoal reached epidemic levels in Hong Kong and Taiwan within 5 y of the first reported cases in the early 2000s. The objectives of this analysis were to investigate (i) time trends and regional patterns of charcoal-burning suicide throughout East/Southeast Asia during the time period 1995–2011 and (ii) whether any rises in use of this method were associated with increases in overall suicide rates. Sex- and age-specific trends over time were also examined to identify the demographic groups showing the greatest increases in charcoal-burning suicide rates across different countries.
We used data on suicides by gases other than domestic gas for Hong Kong, Japan, the Republic of Korea, Taiwan, and Singapore in the years 1995/1996–2011. Similar data for Malaysia, the Philippines, and Thailand were also extracted but were incomplete. Graphical and joinpoint regression analyses were used to examine time trends in suicide, and negative binomial regression analysis to study sex- and age-specific patterns. In 1995/1996, charcoal-burning suicides accounted for <1% of all suicides in all study countries, except in Japan (5%), but they increased to account for 13%, 24%, 10%, 7%, and 5% of all suicides in Hong Kong, Taiwan, Japan, the Republic of Korea, and Singapore, respectively, in 2011. Rises were first seen in Hong Kong after 1998 (95% CI 1997–1999), followed by Singapore in 1999 (95% CI 1998–2001), Taiwan in 2000 (95% CI 1999–2001), Japan in 2002 (95% CI 1999–2003), and the Republic of Korea in 2007 (95% CI 2006–2008). No marked increases were seen in Malaysia, the Philippines, or Thailand. There was some evidence that charcoal-burning suicides were associated with an increase in overall suicide rates in Hong Kong, Taiwan, and Japan (for females), but not in Japan (for males), the Republic of Korea, and Singapore. Rates of change in charcoal-burning suicide rate did not differ by sex/age group in Taiwan and Hong Kong but appeared to be greatest in people aged 15–24 y in Japan and people aged 25–64 y in the Republic of Korea. The lack of specific codes for charcoal-burning suicide in the International Classification of Diseases and variations in coding practice in different countries are potential limitations of this study.
Charcoal-burning suicides increased markedly in some East/Southeast Asian countries (Hong Kong, Taiwan, Japan, the Republic of Korea, and Singapore) in the first decade of the 21st century, but such rises were not experienced by all countries in the region. In countries with a rise in charcoal-burning suicide rates, the timing, scale, and sex/age pattern of increases varied by country. Factors underlying these variations require further investigation, but may include differences in culture or in media portrayals of the method.
Every year, almost one million people die by suicide globally; suicide is the fifth leading cause of death in women aged 15–49 and the sixth leading cause of death in men in the same age group. Most people who take their own life are mentally ill. For others, stressful events (the loss of a partner, for example) have made life seem worthless or too painful to bear. Strategies to reduce suicide rates include better treatment of mental illness and programs that help people at high risk of suicide deal with stress. Suicide rates can also be reduced by limiting access to common suicide methods. These methods vary from place to place. Hanging is the predominant suicide method in many countries, but in Hong Kong, for example, jumping from a high building is the most common method. Suicide methods also vary over time. For example, after a woman in Hong Kong took her life in 1998 by burning barbecue charcoal in a sealed room (a process that produces the toxic gas carbon monoxide), charcoal burning rapidly went from being a rare method of killing oneself in Hong Kong to the second most common suicide method.
Cases of charcoal-burning suicide have also been reported in several East and Southeast Asian countries, but there has been no systematic investigation of time trends and regional patterns of this form of suicide. A better understanding of regional changes in the number of charcoal-burning suicides might help to inform efforts to prevent the emergence of other new suicide methods. Here, the researchers investigate the time trends and regional patterns of charcoal-burning suicide in several countries in East and Southeast Asia between 1995 and 2011 and ask whether any rises in the use of this method are associated with increases in overall suicide rates. The researchers also investigate sex- and age-specific time trends in charcoal-burning suicides to identify which groups of people show the greatest increases in this form of suicide across different countries.
The researchers analyzed method-specific data on suicide deaths for Hong Kong, Japan, the Republic of Korea, Taiwan, and Singapore between 1995/1996 and 2011 obtained from the World Health Organization Mortality Database and from national death registers. In 1995/1996, charcoal-burning suicides accounted for less than 1% of all suicides in all these countries except Japan (4.9%). By 2011, charcoal-burning suicides accounted for between 5% (Singapore) and 24% (Taiwan) of all suicides. Rises in the rate of charcoal-burning suicide were first seen in Hong Kong in 1999, in Singapore in 2000, in Taiwan in 2001, in Japan in 2003, and in the Republic of Korea in 2008. By contrast, incomplete data from Malaysia, the Philippines, and Thailand showed no evidence of a marked increase in charcoal-burning suicide in these countries over the same period. Charcoal-burning suicides were associated with an increase in overall suicide rates in Hong Kong in 1998–2003, in Taiwan in 2000–2006, and in Japanese women after 2003. Finally, the annual rate of change in charcoal-burning suicide rate did not differ by sex/age group in Taiwan and Hong Kong, whereas in Japan people aged 15–24 and in the Republic of Korea people aged 25–64 tended to have the greatest rates of increase.
These findings show that charcoal-burning suicides increased markedly in several but not all East and Southeast Asian countries during the first decade of the 21st century. Moreover, in countries where there was an increase, the timing, scale, and sex/age pattern of the increase varied by country. The accuracy of these findings is likely to be limited by several aspects of the study. For example, because of the way that method-specific suicides are recorded in the World Health Organization Mortality Database and national death registries, the researchers may have slightly overestimated the number of charcoal-burning suicides. Further studies are now needed to identify the factors that underlie the variations between countries in charcoal-burning suicide rates and time trends reported here. However, the current findings highlight the need to undertake surveillance to identify the emergence of new suicide methods and the importance of policy makers, the media, and internet service providers working together to restrict graphic and detailed descriptions of new suicide methods.
Please access these websites via the online version of this summary at
A
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The charity Healthtalkonline has
Globally, suicide is amongst the leading causes of premature mortality; in 2010, it was the fifth leading cause of death in women and the sixth in men among individuals aged 15–49 y
Previous studies of method availability and suicide have mostly focused on the impact of restricting access to methods
In 1998–2000 there was a rapid rise in suicide by carbon monoxide poisoning from the inhalation of barbecue charcoal gas in Hong Kong and Taiwan
We used data from eight East/Southeast Asian countries (Hong Kong, Taiwan, Japan, the Republic of Korea, Singapore, Malaysia, the Philippines, and Thailand) to investigate time trends in charcoal-burning suicide across different countries and the association between changes in charcoal-burning suicide and overall suicide rates for the years 1995–2011. We also examined sex- and age-specific time trends to identify the demographic groups showing the greatest increases in charcoal-burning suicide rates across different countries. Our overall aim was to establish what can be learnt from the changing incidence of charcoal-burning suicide in this region to inform the prevention of the future emergence of novel suicide methods. Specifically, the objectives of this analysis were to investigate (i) time trends and regional patterns of charcoal-burning suicide throughout East/Southeast Asia during the period 1995–2011 and (ii) whether any rises in use of this method were associated with increases in overall suicide rates. Sex- and age-specific trends over time were also examined to identify the demographic groups showing the greatest increases in charcoal-burning suicide rates across different countries.
The study used only aggregate secondary data that were available openly; no identifiable personal data were used in the study. Ethical approval was thus not required.
To investigate time trends in charcoal-burning suicide in East/Southeast Asia we first systematically identified countries with data available in the World Health Organization (WHO) Mortality Database
There is no specific code for charcoal-burning suicide in the International Classification of Diseases (ICD)
Age-standardised suicide rates for people aged 15 y or above were calculated using the WHO world standard population
Negative binomial regression models were used to estimate the annual rate of change in charcoal-burning suicide rates by sex for all ages and four age groups (15–24, 25–44, 45–64, and 65+ y), for the time periods (i) when there were rises in rates, i.e., from the start of the rise to its peak or to the most recent year when data were available, and (ii) when there were reductions in rates, i.e., from the peak to the most recent year when data were available. The starting and peak years were identified in the joinpoint regression analyses and by visual inspection of the graphs of time trends in charcoal-burning suicide. Negative binomial regression models were used because there was evidence for over-dispersion in the Poisson regression analyses of the data. We calculated incidence rate ratios assuming a linear change in rates. To examine whether the annual rate of change in charcoal-burning suicide differed between sexes or amongst people of different age groups, interaction terms between sex and year or between age group and year were included in the models. Negative binomial regression models were estimated using Stata version 12 (StataCorp).
Year | Hong Kong | Taiwan | Japan |
Republic of Korea | Singapore | ||||||||||
Number | Percent | Rate | Number | Percent | Rate | Number | Percent | Rate | Number | Percent | Rate | Number | Percent | Rate | |
1995 | 3 | 0.4% | 0.1 | 13 | 0.6% | 0.1 | 1,091 | 4.9% | 1.0 | 38 | 0.7% | 0.1 | |||
1996 | 0 | 0.0% | 0.0 | 12 | 0.5% | 0.1 | 1,213 | 5.2% | 1.1 | 20 | 0.3% | 0.1 | 4 | 0.8% | 0.1 |
1997 | 1 | 0.1% | 0.0 | 15 | 0.6% | 0.1 | 1,281 | 5.2% | 1.2 | 30 | 0.5% | 0.1 | 2 | 0.4% | 0.1 |
1998 | 21 | 2.2% | 0.3 | 32 | 1.1% | 0.2 | 1,618 | 4.9% | 1.4 | 32 | 0.3% | 0.1 | 7 | 1.2% | 0.2 |
1999 | 149 | 15.1% | 2.6 | 68 | 2.3% | 0.4 | 1,691 | 5.2% | 1.5 | 26 | 0.3% | 0.1 | 0 | 0.0% | 0.0 |
2000 | 179 | 17.9% | 3.1 | 88 | 2.8% | 0.5 | 1,482 | 4.7% | 1.3 | 28 | 0.4% | 0.1 | 7 | 1.2% | 0.2 |
2001 | 257 | 24.2% | 4.3 | 259 | 7.2% | 1.4 | 1,414 | 4.6% | 1.2 | 43 | 0.5% | 0.1 | 9 | 1.7% | 0.2 |
2002 | 277 | 24.4% | 4.7 | 773 | 19.5% | 4.2 | 1,556 | 4.9% | 1.4 | 68 | 0.7% | 0.2 | 12 | 2.0% | 0.3 |
2003 | 325 | 25.6% | 5.4 | 660 | 16.4% | 3.5 | 3,662 | 10.8% | 3.4 | 85 | 0.7% | 0.2 | 10 | 1.7% | 0.2 |
2004 | 228 | 20.7% | 3.8 | 847 | 20.2% | 4.5 | 3,300 | 10.3% | 3.1 | 70 | 0.5% | 0.2 | 10 | 1.8% | 0.2 |
2005 | 217 | 18.9% | 3.4 | 1,338 | 27.0% | 7.0 | 4,603 | 14.2% | 4.4 | 92 | 0.6% | 0.2 | 17 | 3.5% | 0.4 |
2006 | 165 | 16.9% | 2.7 | 1,576 | 31.2% | 8.2 | 3,575 | 11.2% | 3.5 | 97 | 0.8% | 0.2 | 11 | 2.1% | 0.2 |
2007 | 143 | 15.3% | 2.3 | 1,213 | 26.6% | 6.3 | 3,131 | 9.5% | 3.1 | 115 | 0.8% | 0.3 | 14 | 2.7% | 0.3 |
2008 | 167 | 16.5% | 2.8 | 1,268 | 27.5% | 6.5 | 4,432 | 13.8% | 4.7 | 336 | 2.2% | 0.8 | 13 | 2.6% | 0.3 |
2009 | 181 | 17.7% | 2.8 | 1,271 | 27.7% | 6.4 | 4,454 | 13.6% | 4.6 | 834 | 4.5% | 2.0 | 19 | 3.8% | 0.4 |
2010 | 138 | 13.9% | 2.2 | 1,232 | 27.9% | 6.2 | 4,042 | 12.7% | 4.1 | 782 | 4.3% | 1.8 | 18 | 3.4% | 0.4 |
2011 | 101 | 13.4% | 1.5 | 957 | 24.1% | 4.8 | 2,993 | 9.7% | 3.1 | 1,290 | 7.0% | 3.0 | 23 | 4.9% | 0.4 |
1995 | 3 | 0.6% | 0.1 | 7 | 0.5% | 0.1 | 961 | 6.5% | 1.8 | 25 | 0.7% | 0.1 | |||
1996 | 0 | 0.0% | 0.0 | 10 | 0.6% | 0.1 | 1,051 | 6.8% | 1.9 | 17 | 0.4% | 0.1 | |||
1997 | 1 | 0.2% | 0.0 | 11 | 0.6% | 0.1 | 1,114 | 6.7% | 2.0 | 23 | 0.5% | 0.1 | |||
1998 | 14 | 2.3% | 0.5 | 29 | 1.5% | 0.3 | 1,432 | 6.2% | 2.6 | 26 | 0.4% | 0.1 | |||
1999 | 111 | 17.8% | 3.9 | 62 | 3.1% | 0.7 | 1,506 | 6.5% | 2.7 | 17 | 0.3% | 0.1 | |||
2000 | 116 | 19.0% | 4.2 | 79 | 3.8% | 0.9 | 1,332 | 5.9% | 2.3 | 15 | 0.3% | 0.1 | |||
2001 | 167 | 24.9% | 5.9 | 200 | 8.2% | 2.1 | 1,269 | 5.8% | 2.2 | 32 | 0.5% | 0.2 | |||
2002 | 195 | 25.7% | 6.8 | 572 | 20.9% | 6.1 | 1,389 | 6.1% | 2.4 | 58 | 0.8% | 0.3 | |||
2003 | 238 | 28.4% | 8.4 | 479 | 17.6% | 5.1 | 3,234 | 13.2% | 5.9 | 67 | 0.8% | 0.4 | |||
2004 | 165 | 23.7% | 5.9 | 615 | 21.6% | 6.5 | 2,861 | 12.3% | 5.3 | 54 | 0.6% | 0.3 | |||
2005 | 146 | 20.5% | 4.9 | 973 | 28.4% | 10.2 | 3,990 | 17.0% | 7.5 | 66 | 0.7% | 0.3 | |||
2006 | 112 | 18.7% | 3.9 | 1,182 | 33.4% | 12.3 | 3,062 | 13.6% | 5.9 | 71 | 0.8% | 0.4 | |||
2007 | 96 | 15.9% | 3.3 | 871 | 28.3% | 8.9 | 2,684 | 11.6% | 5.2 | 83 | 0.9% | 0.4 | |||
2008 | 108 | 18.1% | 3.9 | 914 | 28.9% | 9.3 | 3,649 | 16.1% | 7.5 | 259 | 2.6% | 1.2 | |||
2009 | 120 | 18.6% | 4.1 | 922 | 29.2% | 9.2 | 3,721 | 15.9% | 7.5 | 678 | 5.7% | 3.1 | |||
2010 | 92 | 15.0% | 3.1 | 896 | 30.1% | 9.0 | 3,377 | 15.0% | 6.8 | 642 | 5.3% | 2.9 | |||
2011 | 76 | 16.6% | 2.5 | 695 | 25.8% | 6.9 | 2,496 | 11.7% | 5.1 | 1,072 | 8.5% | 5.0 | |||
1995 | 0 | 0.0% | 0.0 | 6 | 0.8% | 0.1 | 130 | 1.7% | 0.2 | 13 | 0.8% | 0.1 | |||
1996 | 0 | 0.0% | 0.0 | 2 | 0.2% | 0.0 | 162 | 2.1% | 0.3 | 3 | 0.2% | 0.0 | |||
1997 | 0 | 0.0% | 0.0 | 4 | 0.4% | 0.0 | 167 | 2.1% | 0.3 | 7 | 0.3% | 0.0 | |||
1998 | 7 | 2.0% | 0.2 | 3 | 0.3% | 0.0 | 186 | 1.9% | 0.3 | 6 | 0.2% | 0.0 | |||
1999 | 38 | 10.6% | 1.3 | 6 | 0.6% | 0.1 | 185 | 2.0% | 0.3 | 9 | 0.4% | 0.0 | |||
2000 | 63 | 16.2% | 2.1 | 9 | 0.8% | 0.1 | 150 | 1.6% | 0.3 | 13 | 0.5% | 0.1 | |||
2001 | 90 | 23.1% | 2.8 | 59 | 5.1% | 0.6 | 145 | 1.7% | 0.3 | 11 | 0.4% | 0.1 | |||
2002 | 82 | 21.9% | 2.7 | 201 | 16.4% | 2.2 | 167 | 1.9% | 0.3 | 10 | 0.3% | 0.1 | |||
2003 | 87 | 20.1% | 2.8 | 181 | 13.8% | 2.0 | 428 | 4.6% | 0.8 | 18 | 0.5% | 0.1 | |||
2004 | 63 | 15.5% | 2.0 | 232 | 17.4% | 2.5 | 439 | 4.9% | 0.8 | 16 | 0.4% | 0.1 | |||
2005 | 71 | 16.1% | 2.1 | 365 | 23.8% | 3.9 | 613 | 6.8% | 1.2 | 26 | 0.6% | 0.1 | |||
2006 | 53 | 14.1% | 1.6 | 394 | 26.0% | 4.1 | 513 | 5.6% | 1.0 | 26 | 0.6% | 0.1 | |||
2007 | 47 | 14.2% | 1.4 | 342 | 23.2% | 3.6 | 447 | 4.7% | 0.9 | 32 | 0.6% | 0.1 | |||
2008 | 59 | 14.3% | 1.8 | 354 | 24.3% | 3.7 | 783 | 8.4% | 1.8 | 77 | 1.4% | 0.4 | |||
2009 | 61 | 16.0% | 1.7 | 349 | 24.4% | 3.7 | 733 | 7.9% | 1.6 | 156 | 2.4% | 0.8 | |||
2010 | 46 | 12.2% | 1.4 | 336 | 23.4% | 3.4 | 665 | 7.1% | 1.4 | 140 | 2.3% | 0.7 | |||
2011 | 25 | 8.5% | 0.7 | 262 | 20.4% | 2.7 | 497 | 5.1% | 1.1 | 218 | 3.7% | 1.1 |
Rate per 100,000 is age-standardised, except Singapore, for which rates were crude rates.
In Japan, figures for 2008 onwards included not only charcoal-burning suicides but also some deaths from hydrogen sulphide poisoning, which increased markedly in 2008
Year | Malaysia | Philippines | Thailand | ||||||
Number | Percent | Rate | Number | Percent | Rate | Number | Percent | Rate | |
1995 | 0 | 0.0% | 0.00 | ||||||
1996 | 3 | 0.1% | 0.01 | ||||||
1997 | 1 | 0.0% | 0.00 | ||||||
1998 | 2 | 0.0% | 0.00 | ||||||
1999 | 3 | 0.2% | 0.01 | 18 | 0.2% | 0.04 | |||
2000 | 9 | 0.4% | 0.06 | 3 | 0.1% | 0.01 | 18 | 0.1% | 0.04 |
2001 | 28 | 1.2% | 0.16 | 10 | 0.2% | 0.04 | |||
2002 | 38 | 1.5% | 0.24 | 7 | 0.1% | 0.01 | 5 | 0.0% | 0.01 |
2003 | 50 | 1.8% | 0.30 | 20 | 0.4% | 0.08 | 2 | 0.0% | 0.00 |
2004 | 29 | 1.0% | 0.18 | 3 | 0.0% | 0.01 | |||
2005 | 49 | 1.7% | 0.29 | 0 | 0.0% | 0.00 | |||
2006 | 23 | 0.9% | 0.15 | 1 | 0.0% | 0.00 | |||
2007 | 46 | 1.8% | 0.26 | ||||||
2008 | 25 | 0.9% | 0.13 | 7 | 0.1% | 0.01 | |||
1995 | 0 | 0.0% | 0.00 | ||||||
1996 | 3 | 0.1% | 0.02 | ||||||
1997 | 0 | 0.0% | 0.00 | ||||||
1998 | 2 | 0.0% | 0.01 | ||||||
1999 | 3 | 0.2% | 0.01 | 13 | 0.1% | 0.05 | |||
2000 | 7 | 0.4% | 0.09 | 2 | 0.0% | 0.01 | 12 | 0.1% | 0.05 |
2001 | 25 | 1.3% | 0.29 | 5 | 0.1% | 0.03 | |||
2002 | 29 | 1.4% | 0.35 | 5 | 0.1% | 0.02 | 2 | 0.0% | 0.01 |
2003 | 43 | 2.0% | 0.52 | 9 | 0.2% | 0.10 | 2 | 0.0% | 0.01 |
2004 | 27 | 1.2% | 0.34 | 3 | 0.0% | 0.01 | |||
2005 | 44 | 1.9% | 0.52 | 0 | 0.0% | 0.00 | |||
2006 | 19 | 0.9% | 0.23 | 1 | 0.0% | 0.00 | |||
2007 | 34 | 1.7% | 0.37 | ||||||
2008 | 18 | 0.8% | 0.20 | 5 | 0.1% | 0.02 | |||
1995 | 0 | 0.0% | 0.00 | ||||||
1996 | 0 | 0.0% | 0.00 | ||||||
1997 | 1 | 0.1% | 0.00 | ||||||
1998 | 0 | 0.0% | 0.00 | ||||||
1999 | 0 | 0.0% | 0.00 | 5 | 0.2% | 0.02 | |||
2000 | 2 | 0.4% | 0.02 | 1 | 0.1% | 0.00 | 6 | 0.2% | 0.03 |
2001 | 3 | 0.7% | 0.03 | 5 | 0.4% | 0.04 | |||
2002 | 9 | 2.1% | 0.11 | 2 | 0.2% | 0.01 | 3 | 0.1% | 0.01 |
2003 | 7 | 1.3% | 0.07 | 11 | 0.8% | 0.06 | 0 | 0.0% | 0.00 |
2004 | 2 | 0.4% | 0.03 | 0 | 0.0% | 0.00 | |||
2005 | 5 | 0.9% | 0.05 | 0 | 0.0% | 0.00 | |||
2006 | 4 | 0.8% | 0.07 | 0 | 0.0% | 0.00 | |||
2007 | 12 | 2.3% | 0.15 | ||||||
2008 | 7 | 1.3% | 0.07 | 2 | 0.1% | 0.01 |
Joinpoint regression analysis showed that the rise in charcoal-burning suicide began after 1998 (95% CI 1997–1999) in Hong Kong, 1999 (95% CI 1998–2001) in Singapore, 2000 (95% CI 1999–2001) in Taiwan, 2002 (95% CI 1999–2003) in Japan, and 2007 (95% CI 2006–2008) in the Republic of Korea (
Red arrows indicate the years when charcoal-burning suicides started to increase.
Country | Suicide Method | Segment 1 |
Join Point 1 | Segment 2 |
Join Point 2 | Segment 3 |
|||||
β | 95% CI | Year | 95% CI | β | 95% CI | Year | 95% CI | β | 95% CI | ||
Charcoal-burning suicide | 0.03 | −0.12, 0.19 | 1998 | 1997, 1999 | 1.67 | 0.19, 3.14 | 2001 | 1999, 2004 | −0.34 | −0.45, −0.23 | |
Suicide by other methods | −0.27 | −0.38, −0.16 | |||||||||
Overall suicide | 0.63 | 0.26, 1.01 | 2003 | 2001, 2005 | −0.89 | −1.23, −0.55 | |||||
Charcoal-burning suicide | 0.07 | −0.02, 0.15 | 2000 | 1999, 2001 | 1.21 | 0.83, 1.58 | 2006 | 2004, 2008 | −0.50 | −0.97, −0.02 | |
Suicide by other methods | 1.51 | 0.26, 2.76 | 1997 | 1997, 2002 | 0.18 | 0.02, 0.35 | 2005 | 2003, 2007 | −0.74 | −0.93, −0.56 | |
Overall suicide | 1.01 | 0.85, 1.16 | 2006 | 2005, 2007 | −1.21 | −1.70, −0.72 | |||||
Charcoal-burning suicide | 0.05 | −0.07, 0.16 | 2002 | 1999, 2003 | 2.10 | — |
2003 | 2002, 2009 | 0.05 | −0.12, 0.23 | |
Suicide by other methods | 0.58 | −0.89, 2.05 | 1997 | 1997, 1998 | 6.06 | — |
1998 | 1998, 1999 | −0.24 | −0.33, −0.15 | |
Overall suicide | 0.66 | −1.08, 2.41 | 1997 | 1997, 1998 | 6.14 | — |
1998 | 1998, 1999 | 0.02 | −0.09, 0.13 | |
Charcoal-burning suicide | 0.02 | 0.01, 0.03 | 2007 | 2006, 2008 | 0.65 | 0.49, 0.82 | |||||
Suicide by other methods | 1.52 | 1.26, 1.77 | |||||||||
Overall suicide | 0.65 | 0.41, 0.90 | |||||||||
Charcoal-burning suicide | −0.03 | −0.10, 0.04 | 1999 | 1998, 2001 | 0.18 | — |
2000 | 1999, 2006 | 0.02 | 0.01, 0.03 | |
Suicide by other methods | 0.00 | −0.35, 0.35 | 2002 | 1998, 2005 | −0.54 | −0.70, −0.38 | |||||
Overall suicide | 0.03 | −0.32, 0.37 | 2002 | 1998, 2005 | −0.52 | −0.68, −0.36 |
Rates per 100,000 are age-standardised rates for Taiwan, Japan, and the Republic of Korea, and crude rates for Hong Kong and Singapore. Data for Singapore are for 1996–2011.
Segments were linear trends between join points (i.e., the years when the trends changed) identified using joinpoint regression, which characterises time trends as contiguous linear segments and join points.
95% CI could not be estimated by the joinpoint regression as the segment included only two data points.
β, mean annual increase in suicide rate per 100,000.
If the year following the join point when the time trend turned upward is defined as the year when the increase in charcoal-burning suicide began (indicated by arrows in
Combined numbers of charcoal-burning suicides for the five study countries reached a peak in 2009 (
Graphical examinations of time trends in suicide are presented in
Country | Age Group | Males and Females | Males | Females | |||||
IRR | 95% CI | IRR | 95% CI | IRR | 95% CI | Sex×Year | Age×Year | ||
Hong Kong (1998–2001) | 0.75 | 0.87 | |||||||
All ages | 1.95 | 1.47, 2.58 | 1.85 | 1.38, 2.48 | 1.82 | 1.50, 2.20 | |||
Aged 15–24 y | 1.98 | 1.18, 3.32 | 1.73 | 1.16, 2.59 | 1.97 | 0.96, 4.06 | |||
Aged 25–44 y | 1.91 | 1.35, 2.70 | 1.81 | 1.22, 2.68 | 1.88 | 1.48, 2.40 | |||
Aged 45–64 y | 1.84 | 0.82, 4.14 | 1.91 | 0.79, 4.59 | 1.49 | 0.96, 2.31 | |||
Aged 65+ y | 2.54 | 2.54, 2.54 | 1.68 | 0.91, 3.12 | 2.68 | 0.96, 7.46 | |||
Taiwan (2000–2006) | 0.66 | 0.96 | |||||||
All ages | 1.49 | 1.37, 1.61 | 1.46 | 1.36, 1.57 | 1.53 | 1.37, 1.71 | |||
Aged 15–24 y | 1.54 | 1.29, 1.85 | 1.53 | 1.27, 1.83 | 1.45 | 1.26, 1.69 | |||
Aged 25–44 y | 1.45 | 1.25, 1.68 | 1.42 | 1.25, 1.61 | 1.53 | 1.18, 1.99 | |||
Aged 45–64 y | 1.50 | 1.27, 1.77 | 1.46 | 1.26, 1.71 | 1.57 | 1.29, 1.93 | |||
Aged 65+ y | 1.47 | 1.32, 1.64 | 1.49 | 1.33, 1.68 | 1.44 | 1.13, 1.84 | |||
Japan (2002–2005) |
0.37 | 0.064 | |||||||
All ages | 1.40 | 1.25, 1.58 | 1.38 | 1.24, 1.55 | 1.46 | 1.28, 1.66 | |||
Aged 15–24 y | 1.68 | 1.36, 2.08 | 1.63 | 1.33, 2.00 | 1.74 | 1.38, 2.19 | |||
Aged 25–44 y | 1.46 | 1.15, 1.86 | 1.44 | 1.13, 1.83 | 1.62 | 1.24, 2.12 | |||
Aged 45–64 y | 1.26 | 1.07, 1.48 | 1.25 | 1.06, 1.48 | 1.29 | 1.15, 1.46 | |||
Aged 65+ y | 1.26 | 1.04, 1.52 | 1.26 | 1.06, 1.50 | 1.21 | 0.97, 1.51 | |||
Republic of Korea (2007–2010) | 0.22 | 0.096 | |||||||
All ages | 1.60 | 1.42, 1.81 | 1.64 | 1.45, 1.85 | 1.44 | 1.29, 1.62 | |||
Aged 15–24 y | 1.59 | 1.27, 1.99 | 1.54 | 1.29, 1.84 | 1.57 | 1.13, 2.18 | |||
Aged 25–44 y | 1.80 | 1.43, 2.28 | 1.84 | 1.45, 2.33 | 1.61 | 1.31, 1.97 | |||
Aged 45–64 y | 1.74 | 1.41, 2.15 | 1.79 | 1.42, 2.25 | 1.46 | 1.22, 1.74 | |||
Aged 65+ y | 1.27 | 1.10, 1.46 | 1.33 | 1.12, 1.57 | 1.15 | 0.97, 1.35 | |||
Hong Kong (2003–2011) | 0.53 | 0.67 | |||||||
All ages | 0.89 | 0.86, 0.91 | 0.89 | 0.86, 0.91 | 0.90 | 0.87, 0.93 | |||
Aged 15–24 y | 0.87 | 0.79, 0.96 | 0.84 | 0.76, 0.94 | 0.93 | 0.80, 1.07 | |||
Aged 25–44 y | 0.88 | 0.85, 0.90 | 0.87 | 0.84, 0.90 | 0.90 | 0.86, 0.94 | |||
Aged 45–64 y | 0.90 | 0.86, 0.95 | 0.91 | 0.87, 0.96 | 0.89 | 0.84, 0.94 | |||
Aged 65+ y | 0.91 | 0.82, 1.01 | 0.89 | 0.79, 1.00 | 1.03 | 0.81, 1.31 | |||
Taiwan (2006–2011) | 0.86 | 0.55 | |||||||
All ages | 0.93 | 0.90, 0.95 | 0.93 | 0.90, 0.95 | 0.94 | 0.91, 0.96 | |||
Aged 15–24 y | 0.91 | 0.86, 0.97 | 0.91 | 0.85, 0.97 | 0.91 | 0.82, 1.02 | |||
Aged 25–44 y | 0.92 | 0.88, 0.96 | 0.91 | 0.87, 0.95 | 0.95 | 0.92, 0.98 | |||
Aged 45–64 y | 0.93 | 0.90, 0.97 | 0.94 | 0.90, 0.99 | 0.91 | 0.86, 0.95 | |||
Aged 65+ y | 0.97 | 0.91, 1.05 | 0.96 | 0.88, 1.04 | 1.06 | 0.90, 1.25 |
The peak year (2005) for Japan was determined by inspecting the time trends to identify the year when charcoal-burning suicide rate was the highest before 2008, as from 2008 onwards suicides classified as other gas poisoning included not only charcoal-burning suicides but also some deaths from hydrogen sulphide poisoning
IRR, incidence rate ratio.
Charcoal-burning suicides increased markedly in some East/Southeast Asian countries (Hong Kong, Taiwan, Japan, the Republic of Korea, and Singapore) in the first decade of the 21st century, but such rises were not experienced by all countries in the region. In countries with a rise in the charcoal-burning suicide rate, the timing, scale, and sex/age pattern of the increase varied by country. A rise in charcoal-burning suicides was first seen in Hong Kong (1999), followed by Singapore (2000), Taiwan (2001), Japan (2003), and the Republic of Korea (2008), although the evidence for a definite starting year for Singapore was limited because of relatively small suicide numbers. Evidence for an association between the charcoal-burning suicide rate and the overall suicide rate varied by country—an association was found in Hong Kong, Taiwan, and Japan (for females), but not in Japan (for males), the Republic of Korea, and Singapore. Combined numbers of charcoal-burning suicides for the five study countries reached a peak in 2009, resulting in around 6,800 deaths. Compared to the baseline levels prior to the increase in charcoal-burning suicide in individual countries, by 2011 there were nearly 50,000 excess suicides by charcoal burning in total. Annual rates of changes in charcoal-burning suicide rates did not differ by sex/age group in Taiwan and Hong Kong, whilst people aged 15–24 y in Japan and people aged 25–64 y in the Republic of Korea tended to have the greatest rates of increase.
Our data showed that the increases in charcoal-burning suicide were associated with various levels of changes in overall suicide rates across the East/Southeast Asian countries studied. The increase in charcoal-burning suicide first started in Hong Kong and Taiwan, where it was associated with a rise in overall suicide rates, followed by an increase in Japan, where the rise in overall suicide was less obvious, and then in the Republic of Korea, where the increase in charcoal-burning suicide was very recent, and further investigation of its association with any changes in overall suicide rate is needed. In contrast, Singapore had a much smaller rise in charcoal-burning suicide than other countries did.
To the best of our knowledge, this is the first systematic investigation of the rise in the popularity of charcoal burning as a method of suicide across East/Southeast Asian countries. There are several limitations to this study. First, we were not able to differentiate charcoal-burning suicides from deaths using other sources of non-domestic gas, such as car exhaust fumes or hydrogen sulphide. However, previous studies found that charcoal-burning suicide accounted for over 90% of all suicides from non-domestic gas poisoning in Hong Kong
Second, the quality of suicide data may vary by country and change over time. One important factor of under-reporting is the misclassification of suicides as deaths of other causes, such as death of undetermined intent
Third, we did not include data for some East/Southeast Asian countries where cases of charcoal-burning suicide were also reported recently, such as China
Several factors may have contributed to differences in the timing, scale, and sex/age pattern of rises in charcoal-burning suicide amongst East/Southeast Asian countries. How and the extent to which the media reported the first or first few cases of charcoal-burning suicide may have played an important role in the adoption pattern of the method. It has been reported that extensive media reporting of cases was followed by an increase in charcoal-burning suicide in Hong Kong
Variations in familiarity with coal or charcoal and their accessibility are also possible contributors to the difference between countries in the uptake of this suicide method. In Hong Kong and Taiwan, barbecue charcoal is readily accessible at local shops; such easy availability and familiarity with barbecue charcoal may have contributed to the rapid increases in charcoal-burning suicide in these countries. In contrast, charcoal-burning suicides were usually referred to in Japan as suicides using “rentan”
In Hong Kong, charcoal-burning suicides emerged in 1998–1999, following the Asian economic crisis in 1997–1998, which was shown to have a strong impact on Hong Kong's economy and suicide patterns
Our data showed that—for both the time periods when charcoal-burning suicide rates rose and fell—the rate of change did not differ by sex or age group in Taiwan or Hong Kong. In contrast, young males and females in Japan as well as middle-aged males and young females in the Republic of Korea appeared to have the most rapid increase in charcoal-burning suicide compared to other age groups, although the statistical evidence for age interaction was not significant (
Our results have several implications for international and regional suicide prevention strategies. First, our findings indicate that it is important to undertake surveillance to identify the emergence of new suicide methods. Such surveillance may include investigating the characteristics of suicide attempts in which such methods are first adopted, and the channels through which information about the new method spreads. Such information will help identify potential measures that may prevent or stop the use of new dangerous methods at an early stage. Second, it is crucial to work with the media and policy makers to restrict graphic descriptions of novel suicide methods and technical information about how to use them. Similarly, it is also important to work with internet service providers to regulate online content containing the details of dangerous methods, which may contribute to the increasing use of new suicide methods not only within but also across country boundaries. Both such measures will limit the cognitive availability of new, high-lethality methods
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International Classification of Diseases
ninth revision of International Classification of Diseases
tenth revision of International Classification of Diseases
World Health Organization