Chi-Kin Law

Charcoal burning suicides in Hong Kong and urban Taiwan: an illustration of the impact of a novel suicide method on overall regional rates

Objectives: Following the first case in Hong Kong in 1998, the method of committing suicide by charcoal burning has spread to other communities. This aim of this study was to examine the impact of charcoal burning suicides on both overall suicide rates and older-method suicide rates in Hong Kong and urban Taiwan. Design: Trend analysis of the overall and method-specific suicide rates between 1997 and 2002. Comparison of age and gender profiles of those who committed suicide by charcoal burning and other methods of suicide. Setting: Hong Kong and Urban Taiwan. Main results: Suicides by charcoal burning increased rapidly within five years in both Hong Kong and urban Taiwan. This increase was not paralleled by decreases in suicides by older methods and led to an increase of more than 20% in the overall suicide rates. Those in the 24–39 age range were more likely to choose charcoal burning than other methods. Conclusions: The lack of parallel decreases in the suicides rates of older methods with the rise of charcoal burning suicides suggests limited substitution between the methods. The preponderance of the rise in suicide deaths associated with charcoal burning suggests that its invention, followed by wide media dissemination, may have specifically contributed to the increase in suicides in both regions. As a similar increase was found in urban Taiwan as in Hong Kong, charcoal burning suicide should not be viewed as merely a local health problem and has the potential to become a major public health threat in other countries.

Silicon nanotubes: Why not?

Abstract A diamond nanowire (CNW), a silicon nanowire (SiNW), a carbon nanotube (CNT), and a silicon nanotube (SiNT) were studied using the semiempirical molecular orbital PM3 method, with confirmations by calculations at the HF/3-21G and HF/3-21G(d) levels. It was shown that the systems with a diamond structure generally possess larger band gaps than their tubular counterparts. Carbon nanotubular structure shows efficient sp 2 hybridization and π bonding, thus allowing a high stability of the carbon nanotube structure. In contrast, silicon prefers sp 3 hybridization and favors the tetrahedral diamond-like structures, thereby forming the commonly observed nanowires. This distinction can be traced to the differences in the energetics and overlaps of the valence s and p orbitals of C vs Si. Nevertheless, when the dangling bonds are properly terminated, SiNT can in principle be formed. The resulting energy minimized SiNT, however, adopts a severely puckered structure (with a corrugated surface) with Siue5f8Si distances ranging from 1.85 to 2.25 A.

Evaluating the effectiveness of barrier installation for preventing railway suicides in Hong Kong

BACKGROUNDnRailway suicide is a serious mortality issue. Most attempters are unmarried psychotic young men under psychiatric care having a high level of lethal intent. Installation of platform screen doors (PSDs) to limit access to the track has been suggested as an effective way for prevention. This study aims to examine the effectiveness of installing PSDs for preventing railway suicides; any sign of substitution of suicide location; and changes in psychiatric profile of suicide deceased after the PSD installation in the subway system of Hong Kong.nnnMETHODSnCases of railway suicide and related information from 1997 to 2007 were provided by the railway operators and the Coroners Court. The effectiveness of installing PSDs was assessed through a quasi-experimental setting. Poisson regression and chi-squared test were used.nnnRESULTSnOver the 11-year study period, a total of 76 railway suicide cases (0.71% of all suicides) were reported. A significant reduction of 59.9% (p=0.0003) in railway suicides was found after the PSD installation. Analyses confirmed that there was no significant sign of substitution by displacing potential attempters to unsealed platforms (p=0.9051). Those having psychosis would be better protected as no suicide cases with such psychiatric background were reported after the installation of PSDs.nnnLIMITATIONSnIt has not considered the potential economic benefits of PSD. It is difficult if not possible to examine whether the potential attempters would substitute to an alternative method of suicide.nnnCONCLUSIONSnThis study shows that PSDs can effectively prevent suicides with no substitution by delethalizing the image and altering peoples perception about the desirability of railway suicide. Railway operators should extend the coverage of PSD to all railway stations in Hong Kong without any delay.

Restricting the means of suicide by charcoal burning

We conducted an exploratory controlled trial to examine the efficacy of restricting access to charcoal in preventing suicides from carbon monoxide poisoning by charcoal burning in Hong Kong. All charcoal packs were removed from the open shelves of major retail outlets in the intervention region for 12 months; in the control region, charcoal packs were displayed as usual. The suicide rate from charcoal burning was reduced by a statistically significant margin in the intervention region (P<0.05) but not in the control region. We observed no significant change in the suicide rate using other methods in either location.

Psychological factors associated with the incidence and persistence of suicidal ideation.

BACKGROUNDnSuicidal ideation has been identified as both a common antecedent and a significant risk factor for suicide attempt and completed suicide. However, little is known about the incidence and persistence of suicidal ideation in the general population and the associated risk factors.nnnMETHODSnA 12-month follow-up survey investigated 997 of the respondents who participated in the baseline territory-wide survey of adult population in Hong Kong. A set of baseline psychological factors was considered as predictors of first onset and persistence of suicidal ideation.nnnRESULTSnTwelve-month incidence (1.9%) and persistence (6.2%) rates were estimated. Respondents with anxiety and lack of reasons for living were more likely to report a development of suicidal thoughts in the follow-up assessment, while respondents with higher level of average life distress and lower level of hope were at increased risk of continuing to have suicidal thoughts. Depression was found to partially mediate the effect of average life distress on persistent suicidality.nnnLIMITATIONSnRetention rate of the follow-up sample was about 50% only. Assessments of suicidal ideation were based on retrospective reports.nnnCONCLUSIONSnPsychological factors differentially predict first onset and persistence of suicidal ideation. It is of clinical value that depression partially mediated the effect of life distress on persistence of suicidality.

Social and economic burden of suicides in Hong Kong SAR: A year of life lost perspective

The paper proposes to use the years-of-life-lost method (YLL) in assessing the social and economic burden of suicides in Hong Kong SAR. The YLL from suicide by age group in 1981-2002 is calculated based on the standard set by World Health Organization (WHO). It shows that the middle age group (25-39) contributed most to the burden of disease in Hong Kong. The proportion of older adults suicides is about 25% of the total number of suicides but its disease burden is less than 6% in terms of the YLL. Though the group aged 25-39 contributed disproportionately to the total YLL from suicide, the prevention effort for this particular group has been very much neglected and needs to be strengthened. It illustrates that use of YLL could provide a new viewpoint for setting up public health policies.

The Economic and Potential Years of Life Lost from Suicide in Taiwan, 1997–2007

BACKGROUNDnTaiwan has experienced a marked increase in the suicide rate in the last decade. However, the socioeconomic burden and impact to the community has not been adequately assessed.nnnAIMSnThis study aimed to estimate the social and economic burden of premature mortality from suicide in Taiwan in 1997-2007.nnnMETHODSnThe suicide rate, potential years of life lost (PYLL), and present value of lifetime earnings (PVLE) by sex and age groups in 1997-2007 were calculated. The contribution of each suicide method to PYLL for each age group was also assessed.nnnRESULTSnUsing the PYLL calculations, suicide had become the third leading cause of death in Taiwan in 2007, compared to its ninth position in terms of absolute numbers. Furthermore, the PYLL was associated with an estimated NTD (New Taiwan Dollars) 32.5 billion of lost earnings in 2007. The increase in PYLL and PVLE from suicide was highest in middle-aged men (aged 25-59 years). Charcoal burning suicide accounted for most of the increase in PYLL in the middle-aged group in the past decade.nnnCONCLUSIONSnThe loss of life in middle-aged males contributes disproportionately to the social and economic burden of suicide in Taiwan. Suicide intervention effort should target this high-risk population.

Years of Life Lost from Suicide in China, 1990–2000

Suicide is an important public health problem in China: It is the fifth leading cause of death in China, and suicide in China accounts for over 30% of the worlds overall suicide deaths. The substantial burden due to suicide has not been well recognized. This study aims to provide an estimate of the socioeconomic burden of the suicide problem in China in terms of years of life lost (YLL) and to discuss its implications. Suicide rates and the related YLL by age, gender, and region (urban/rural) from 1990 to 2000 were estimated using the most recent data from the Ministry of Health of China. The suicide rate in rural China was three times higher than that in urban areas. Suicide completers in rural areas shared 90% of total YLL. Rural women aged 25-39 years contributed the largest share of YLL. Our results show that some population subgroups contributed a disproportionate share to the disease burden of suicide. National strategies for suicide prevention should include targeted programs in catering the need of these specified subgroups in China.

The contribution of charcoal burning to the rise and decline of suicides in Hong Kong from 1997-2007.

BackgroundThere has been scant research exploring the relationship between choice of method (means) of self-inflicted death, and broader social or contextual factors. The recent emergence and growth of suicide using carbon monoxide poisoning resulting from burning charcoal in an enclosed space (hereafter, “charcoal burning”) was related to an increase in the overall suicide rate in Hong Kong. The growth of this method coincided with changing economic conditions. This paper expands upon previous work to explore possible relationships further.PurposeThis study aims to discern the role of charcoal burning in overall suicide rate transition during times of both economic recession and expansion, as captured in the unemployment rate of Hong Kong, and to examine whether there was evidence of an effect from means-substitution.MethodsAge and gender specific suicide rates in Hong Kong by suicide methods from 1997 to 2007 were calculated. To model the transition of suicide rate by different methods, Poisson regression analyses were employed.ResultsCharcoal burning constituted 18.3% of all suicides, 88% of which involved individuals drawn from the middle years (25–59) of life. During both periods of rising and declining unemployment, charcoal burning played an important role in the changing suicide rates, and this effect was most prominent among for those in their middle years. Means-substitution was found among the married women during the period of rate advancement (1997–2003).ConclusionsCompared to others, working-age adults preferentially selected carbon monoxide poisoning from charcoal burning.

An economic evaluation of setting up physical barriers in railway stations for preventing railway injury: evidence from Hong Kong

Background Setting physical barriers, for example platform screen doors (PSDs), has been proven to be effective in preventing falls onto railway tracks, but its cost-effectiveness is not known. For economic evaluation of public health interventions, the importance of including non-health factors has been noted despite a lack of empirical studies. This study aimed to investigate the effectiveness and cost-effectiveness of PSDs, which are installed in part of the Hong Kong railway system, for preventing railway injuries. Methods Data on railway injuries from 1997 to 2007 were obtained from the railway operators. Poisson regression was used to examine the risk reduction. Two incremental cost-effectiveness ratios (ICER) were calculated to assess the cost-effectiveness based on (1) disability-adjusted life years (DALYs) only and (2) DALYs with potential fare revenue and passengers waiting time lost due to railway circulation collapse. Results The PSD installation has effectively reduced railway injuries (adjusted 5-year average percentage change: −68.8%, p<0.0001) with no apparent substitution effect to the other platforms observed. To be cost-effective, the cost of gaining a healthy life year (ICER) should not exceed three times the per capita GDP (US