Lethality of suicide methods A A ElnourJ Harrison Research Centre for Injury Studies, Flinders University, Adelaide, SA, Australia

Outline Introduction Methods Results Discussion Comments Luo Xiaomin Zhang Xia

Introduction Suicide is a major public health problem. Establishing the effectiveness of preventive interventions is challenging. Availability of suicide means can influence suicide occurrence. Restricting availability may decrease overall suicide rates.

Introduction Published data are lacking on case fatality. Examining case fatality by sex, age, and time will improve understanding of suicidal behavior and might aid prevention.

Introduction Objectives  Quantify the lethality of suicide methods used in Australia in the period 1 July 1993 to 30 June 2003  Examine method-specific case fatality by age and sex  Identify changes in case fatality during the study period

Outline Methods Results Discussion Comments

Methods Data source  Completed suicides (deaths) : National Mortality Files (n=24 194) Australian Bureau of Statistics(ABS)  Cases resulting in hospitalization due to intentional self-harm : Australia’s National Hospital Morbidity Database (n= ) Australian Institute of Health and Welfare (AIHW)

Methods 1. Firearms 2. Hanging, Strangulation and Suffocation (Hanging/Suffocation) 3. Poisoning by gases and vapors (Gases/Vapors) 4. Poisoning by and exposure to solid or liquid substances (Drugs/Poisons) 5. Drowning and Submersion 6. Jumping from a height 7. Cutting and piercing by sharp objects (sharp objects) 8. Lying or jumping before a moving object 9. Crashing a motor vehicle 10. Other and unspecified Specified 10 types of method of self-harm in terms of ICD-9 and ICD-10.

Methods Definition  ‘‘Fatal episodes’’ of self-harm means completed suicides  ‘‘Non-fatal episodes’’ of self-harm means cases recorded as being due to intentional self-harm which, based on the available data,were survived  ‘‘Total episodes’’ were estimated as the sum of these.

Methods Double counting of cases recorded in both sources was controlled by omitting fatal hospital cases from estimates of episodes of self-harm. Case lethality for each method was estimated by dividing suicide deaths for that method by total episodes involving the same suicide method. Confidence intervals assume a Poisson distribution of cases, hence used Poisson regression and non-parametric tests.

Outline Results Discussion Comments

Case fatality Overall, of the total episodes (n= ), 12% resulted in death (24 194).

Total episodes of intentional self-harm increased Fatal episodes increased and then decreased Non-fatal episodes increased

Method-specific rates Firearms were the most lethal suicide means (90%) followed by hanging (83%) *Total, fatal, and non- fatal episodes are annual average rates per population for the 10-year period 1 July 1993 to 30 June 2003.

Figure 2 Method-specific case fatality by sex, Australia, 1 July 1993 to 30 June For each suicide method, case fatality was higher in males.

Figure 3 Method-specific case fatality by age, Australia, 1 July 1993 to 30 June For each suicide method, case fatality was higher in older age groups.

Figure 4 Method-specific time trends in case fatality, Australia, 1 July 1993 to 30 June Case fatality for firearm cases changed little over time, but declined for self- harm by hanging/suffoca tion, poisoning, sharp objects, and crashing a motor vehicle.

Outline Discussion Comments

Review the results briefly Overall case fatality was 12%. Case fatality was higher in males and older age groups. Firearms were the most lethal suicide means(90%). Hanging is the second method(83%). Rates of suicide such as firearms declined over time, but those involving hanging rose. Case fatality for firearm cases changed little, but other self-harm means declined.

Discussion---advantage Broaden the view by using both hospital data (non-fatal episodes) and death data (fatal episodes). Study the lethality of the suicide methods and the case fatality varies over time.

Discussion 1 The rate of non-fatal episodes increased through the period, whereas the rate of fatal episodes rose until 1997–98, then fell. Methods of self-harm changed (with an overall decrease in case fatality) Changes in retrieval or treatment (increase in survival from some types of self-harm) Changes in information (eg, changes in case ascertainment).

Discussion 2 Was the rise in suicide by hanging causally related to the decline in suicide by firearms? The relationship between the increase in suicides by hanging and the decrease in firearm related suicides is ambiguous. its occurrence requires more than observing opposing trends.

Discussion 3 Hanging rose dramatically, from 28% to 45% of fatal episodes and even more for non-fatal episodes. Case fatality decline steadily, especially in younger ages.

Discussion 3 One possible explanation: the category ‘‘hanging, strangulation, and suffocation’’ includes sub-types of cases with different lethality and that the mixture of types has changed over time. Other possible explanations: hospital admission practices have changed in a way that increases the proportion of such cases that are admitted (including less lethal types), or that under-ascertainment of fatal cases has increased.

Discussion 4 Poisoning by gases, the second most common method for fatal cases, showed a decline in lethality during the study period. The emission controls have tended to decrease the toxicity of exhaust gas, which may have contributed to the observed decline in lethality.

Discussion 5 The ‘‘gender paradox’’ of suicide The present study does not explain these differences, but prompts questions for future work.

Discussion 6 Case fatality generally increased with age, although with different patterns for each suicide method. The decline with age of physiological robustness probably accounts for part of this effect.

Implications for prevention We should understand suicidality by considering non-fatal as well as fatal cases. The demographic and temporal patterns can usefully inform planning for prevention and interpretation of trends in suicide. Determinants of the pattern of methods used are poorly understood, limiting options for prevention.

Conclusions method-specific lethality by gender and age is so different. Lethality of the suicide methods changes over time. Understanding of suicidality in populations, on which prevention efforts depend, requires explanation of these findings.

Comments 1 The study is a very good research that add the data to the literature of suicidal research. We broaden the view from this paper. The advantages are addressed by the author too many times, now I try to find the limitation of the paper.

Comments 2 This research is a retrospective study,so it has the common limitation of all this type study. It is very hard to do the quality control of the study.

Comments 3 Suicidal problem is so complicated, but this study only choose a little variables such as age and gender. For example, the economic status and the income will decide which self-harm means we choose. Perhaps other variables will work on the results. But we never know according to this research.

Comments 4 As the author says, because of lack of data, Suicidal acts that did not result in hospital admission or death were not included. This may make the selection bias.

Comments 5 It is just a descriptive study. We should design a prospective study that with more variables, well quality control, multivariate analysis.

Comments 6 Because of the different culture, we can not use the conclusion directly. But I think that it is very important to build a national data base of the suicide in China.

Thank you