Do weather, day of the week, and address affect the rate of attempted suicide in Hong Kong?

Suicidality and mood: the impact of trends, seasons, day of the week, and time of day on explicit and implicit cognitions among an online community sample

Decades of research have established seasonality effects on completed and attempted suicides, with rates increasing in spring. Little advancements have been made to explain this phenomenon, with most studies focusing almost exclusively on the number of suicide attempts and deaths. Using more than six years of data collected among a US, UK, and Canadian online community sample (N > 10,000), we used newly developed Prophet forecasting and autoregressive-integrated moving average time-series models to examine the temporal dynamics of explicit and implicit self-harm cognitions. We created three groups (past suicide attempters; suicide ideation and/or non-suicidal self-injury; no previous self-harm, suicidal thoughts, or behaviors). We found a general increase of negative self-harm cognitions across the six years and seasonality effects for mood and desire to die, particularly among those who previously made a suicide attempt. Negative explicit self-harm cognitions peaked in winter (December), with implicit self-harm showing a lagged peak of two months (February). Moreover, daily negative self-harm cognitions consistently peaked around 4-5 am, with implicit cognitions again showing a lagged effect (1-hour). Limitations include the volunteer sample not being representative and the cross-sectional nature of the data being unable to separate between-subject and within-subject structural trends in the time series. Our findings show that negative explicit and implicit cognitions precede the rise in suicidal behaviors in spring. We proposed a conceptual model of seasonal suicide risk that may offer fertile ground for theoretical advancements, including implications for clinical risk assessment and public policies regarding the availability of health services.

[Weather and suicide : Association between meteorological variables and suicidal behavior-a systematic qualitative review article]

BACKGROUND

The effects of current and expected future climate change on mental health outcomes are of increasing concern. In this context, the importance of meteorological factors on suicidal behavior is receiving growing attention in research.

OBJECTIVE

Systematic review article with qualitative synthesis of the currently available literature, looking at the association between meteorological variables and attempted and completed suicide.

MATERIAL AND METHODS

Criteria-based, systematic literature search according to the PRISMA criteria. Peer-reviewed original research studies were included without time limits.

RESULTS AND CONCLUSION

A total of 99 studies were included and grouped according to the research analysis based on daily, weekly, monthly and annual data. The majority of the studies reported a statistical association with at least one meteorological variable. The most consistent positive correlation was shown between temperature and suicidal behavior. However, the results are not conclusive and in part contradictory. The reported studies differed distinctively in terms of study design. Meteorological parameters may be associated with suicidal behavior. Future research in this area is needed to provide further clarity. Despite existing knowledge gaps, the current findings may have implications for suicide prevention plans.

Hot Weather and Suicide Deaths among Older Adults in Hong Kong, 1976-2014: A Retrospective Study

Findings of the association between hot weather and suicide in a subtropical city such as Hong Kong are inconsistent. This study aimed to revisit the association by identifying meteorological risk factors for older-adult suicides in Hong Kong using a time-series approach. A retrospective study was conducted on older-adult (aged ≥65) suicide deaths in Hong Kong from 1976 to 2014. Suicides were classified into those involving violent methods and those involving nonviolent methods. Meteorological data, including ambient temperature, were retrieved. Transfer function time-series models were fitted. In total, 7314 older-adult suicide deaths involving violent methods and 630 involving nonviolent methods were recorded. For violent-method suicides, a monthly average daily minimum ambient temperature was determined to best predict the monthly rate, and a daily maximum ambient temperature of 30.3 °C was considered the threshold. For suicide deaths involving nonviolent methods, the number of days in a month for which the daily maximum ambient temperature exceeded 32.7 °C could best predict the monthly rate. Higher ambient temperature was associated with more older-adult suicide deaths, both from violent and nonviolent methods. Weather-focused preventive measures for older-adult suicides are necessary, such as the provision of more public air-conditioned areas where older adults can shelter from extreme hot weather.

The effect of seasonal changes and climatic factors on suicide attempts of young people

BACKGROUND

Seasonal changes and climatic factors like ambient temperature, sunlight duration and rainfall can influence suicidal behavior.

METHODS

This study analyses the relationship between seasonal changes and climatic variations and suicide attempts in 2131 young patients in Istanbul, Turkey.

RESULTS

In our study sample, there was an association between suicide attempts in youths and seasonal changes, as suicide attempts occurred most frequently during summer in females as well as in males. Furthermore, there was a positive correlation between the mean temperature over the past 10 days and temperature at the index day and suicide attempts in females. After seasonality effects were mathematically removed, the mean temperature 10 days before a suicide attempt remained significant in males only, indicating a possible short-term influence of temperature on suicide attempts.

CONCLUSIONS

This study shows an association between suicide attempts of young people and climatic changes, in particular temperature changes as well as seasonal changes. Therefore, the influence of seasonal changes and climatic factors on young suicide attempters should get more attention in research to understand the biopsychosocial mechanisms playing a role in suicide attempts of young people. As suicide attempts most frequently occur in young people, further research is of considerable clinical importance.

The Clustering and Contagion of Suicide

Two general types of suicide cluster have been discussed in the literature; roughly, these can be classified as mass clusters and point clusters. Mass clusters are media related, and the evidence for them is equivocal; point clusters are local phenomena, and these do appear to occur. Contagion has not been conceptually well developed nor empirically well supported as an explanation for suicide clusters. An alternative explanation for why suicides sometimes cluster is articulated: People who are vulnerable to suicide may cluster well before the occurrence of any overt suicidal stimulus, and when they experience severe negative events, including but not limited to the suicidal behavior of one member of the cluster, all members of the cluster are at increased risk for suicidality (a risk that may be offset by good social support).

Risk Factors for Suicidal Ideation Among Telephone Crisis Hotline Callers in Japan

BACKGROUND

Telephone hotlines are a widely used type of suicide prevention program.

AIMS

The aim of this study was to clarify the risk factors for suicidal ideation by investigating its association with a number of characteristics among telephone hotline callers.

METHOD

Data were collected over a 10-year period from a total of 246,595 calls to Inochi No Denwa, a telephone crisis hotline in Ibaraki, Japan, and subsequently analyzed. Odds ratios for suicidal compared with nonsuicidal ideation were also calculated.

RESULTS

About 6% of the calls to the hotline were suicide related, and about 2% of the callers had attempted suicide in the past. Odds ratios for suicidal ideation increased during winter, but no daily tendencies were evident. Those whose problems were related to their way of life were at the highest risk of suicidal ideation, followed by those with health-related concerns.

CONCLUSION

We were able to identify risk factors for suicidal ideation based on an analysis of enormous amounts of data from a telephone crisis hotline in Japan. Knowledge of these risk factors is expected to lead to improvements in suicide prevention programs.

Association of weekly suicide rates with temperature anomalies in two different climate types

Annual suicide deaths outnumber the total deaths from homicide and war combined. Suicide is a complex behavioral endpoint, and a simple cause-and-effect model seems highly unlikely, but relationships with weather could yield important insight into the biopsychosocial mechanisms involved in suicide deaths. This study has been designed to test for a relationship between air temperature and suicide frequency that is consistent enough to offer some predictive abilities. Weekly suicide death totals and anomalies from Toronto, Ontario, Canada (1986-2009) and Jackson, Mississippi, USA (1980-2006) are analyzed for relationships by using temperature anomaly data and a distributed lag nonlinear model. For both analysis methods, anomalously cool weeks show low probabilities of experiencing high-end suicide totals while warmer weeks are more likely to experience high-end suicide totals. This result is consistent for Toronto and Jackson. Weekly suicide totals demonstrate a sufficient association with temperature anomalies to allow some prediction of weeks with or without increased suicide frequency. While this finding alone is unlikely to have immediate clinical implications, these results are an important step toward clarifying the biopsychosocial mechanisms of suicidal behavior through a more nuanced understanding of the relationship between temperature and suicide.

Atmospheric pressure and suicide attempts in Helsinki, Finland

The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods (P < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

Temporal patterns of charcoal burning suicides among the working age population in Hong Kong SAR: the influence of economic activity status and sex

Background

Charcoal burning in a sealed room has recently emerged as the second most common suicide means in Hong Kong, causing approximately 200 deaths each year. As charcoal burning suicide victims have a unique sociodemographic profile (i.e., predominantly economically active men), they may commit suicide at specific times. However, little is known about the temporal patterns of charcoal burning suicides.

Methods

Suicide data from 2001 to 2008 on victims of usual working age (20–59) were obtained from the registered death files of the Census and Statistics Department of Hong Kong. A total of 1649 cases of charcoal burning suicide were analyzed using a two-step procedure, which first examined the temporal asymmetries in the incidence of suicide, and second investigated whether these asymmetries were influenced by sex and/or economic activity status. Poisson regression analyses were employed to model the monthly and daily patterns of suicide by economic activity status and sex.

Results

Our findings revealed pronounced monthly and daily temporal variations in the pattern of charcoal burning suicides in Hong Kong. Consistent with previous findings on overall suicide deaths, there was an overall spring peak in April, and Monday was the common high risk day for all groups. Although sex determined the pattern of variation in charcoal burning suicides, the magnitude of the variation was influenced by the economic activity status of the victims.

Conclusion

The traditional classification of suicide methods as either violent or nonviolent tends to elide the temporal variations of specific methods. The interaction between sex and economic activity status observed in the present study indicates that sex should be taken into consideration when investigating the influence of economic activity status on temporal variations of suicide. This finding also suggests that suicide prevention efforts should be both time- and subgroup-specific.

Relation between temperature and suicide mortality in Japan in the presence of other confounding factors using time-series analysis with a semiparametric approach

OBJECTIVES

The objective of this study was to assess the relation between temperature and suicide mortality in Japan using time series analysis with a semiparametric approach.

METHODS

We analyzed the relation between daily fluctuations in suicide mortality and maximum temperatures for all regions in Japan over the period of time from 1972 to 1995 using a generalized additive model. The model controls for the time trend, season, selected meteorological parameters, day of the week, and holiday. Adjustment was based using penalized splines and the decision on the amount of smoothness was based on minimizing the unbiased risk estimation criterion.

RESULTS

The results show that suicide mortality in Japan has a seasonal character and it varies from year to year, with the highest occurrence in April, as well as in the first part of the week, especially on Mondays and Tuesdays. As for the day of the week, there were only few suicide cases on Saturdays and holidays. We found that for all regions in Japan when temperature increased the suicide mortality increased on the same day (lag = 0). Analysis by method of suicide showed that when temperature increased mortality significantly increased only for suicide by a violent method. The pattern of the relation for other methods remained unclear.

CONCLUSIONS

This study suggests that an increase in temperature has a short-term effect on suicide mortality in Japan.

Admission to intensive care for parasuicide by self-poisoning: variation by time cycles, climate and the lunar cycle

The aim of this study was to characterize patients after self-poisoning with suicidal intent regarding age, sex and type of substances ingested, as well as to identify temporal variations of attempted suicides and associations with climate variables and the lunar cycle. During the years 2002-2004, a total of 691 patients were admitted for self-poisoning parasuicides. The male to female ratio was 1:1.65 with mean ages of 39 and 37 years, respectively. Benzodiazepines and antidepressants were the most frequently taken substances. A significant variation with the time of the day with a peak before midnight was observed for both sexes. Variation with the day of the week was less clear and showed a peak incidence for parasuicides on Mondays. There was no significant variation with the monthly or annual cycle. The frequency of parasuicides was associated with "bad weather" (precipitation). No association of parasuicide incidences to the lunar cycle was observed.

The Seasonal Risk for Deliberate Self-Harm

Groups at seasonal risk for deliberate self-harm (DSH) vary according to their geographic location. It is unknown, however, if seasonal risk factors for DSH are associated with place of birth or place of residence as these are confounded in all studies to date. In order to disaggregate place of birth from place of residence we examined general and seasonal risk factors for DSH in three different population birth groups living in Western Australia: Australian Aborigines, Australian born non-Aborigines, and UK migrants. We found Aborigines are at much higher general risk for DSH than non-Aborigines, but are not at seasonal risk, whereas non-Aboriginal Australians and UK migrants are. For UK migrants, this is only found for females. For all groups at seasonal risk this peaks during the austral (southern hemisphere) spring/summer. Furthermore, non-Aboriginal Australians and UK migrants show a consistent pattern of increased case fatality with increasing age. In contrast, case fatality does not increase with age among Australian Aborigines. Overall, despite living in the same environment, the three birth groups show different patterns of seasonal risk for DSH. In particular, the sex difference found between UK migrants and non-Aboriginal Australian birth groups suggests that predisposition toward seasonal risk for DSH is established early in life, but when present this is expressed according to local conditions.

Effects of temperature variation on suicide in five U.S. counties, 1991-2001

Effects of weather variables on suicide are well-documented, but there is still little consistency among the results of most studies. Nevertheless, most studies show a peak in suicides during the spring season, and this is often attributed to increased temperatures. The purpose of this study is to test the relationship between monthly temperature and monthly suicide, independent of months or seasons, for five counties located across the United States. Harmonic analysis shows that four of the five counties display some seasonal components in the suicide data. However, simple linear regression shows no correlation between suicide and temperature, and discriminant analysis shows that monthly departure from mean annual suicide rates is not a useful tool for identifying months with temperatures that are colder or warmer than the annual average. Therefore, it appears that the seasonality of suicides is due to factors other than temperature.

Association of meteorological factors with suicide

OBJECTIVE

To identify weather factors associated with an increased risk of suicide. In a number of prior studies an influence of meteorological conditions on the incidence of suicide or attempted suicide has been suggested.

METHOD

Official data on the suicide cases of the state of Tyrol, Austria, assessed over a period of 6 years (n = 702) were correlated with a number of meteorological factors assessed at eight weather stations.

RESULTS

The risk of committing suicide was significantly higher on days with high temperatures, low relative humidity or a thunderstorm and on days following a thunderstorm. The multiple logistic regression analysis left "temperature" and "thunderstorm on the preceding day" as significant factors, even after adjustment for sociodemographic and geographical variables.

CONCLUSION

Within the interaction of psychological and environmental influences in the development of suicidal ideation and behaviour, specific meteorological conditions may additionally contribute to the risk of suicide in predisposed individuals.

Weather and suicide: the present state of knowledge on the association of meteorological factors with suicidal behaviour

OBJECTIVE

To review the available literature on the association between daily and longer-term weather data and the incidence of attempted and completed suicide.

METHOD

A computerized search supplemented by a cross-check of the references sections of the thereby identified papers was performed.

RESULTS

A total of 27 studies looking for a relationship between attempted or completed suicide and weather or climate data were found. Most of the papers reported a statistical association of suicidal acts with at least one weather factor. However, the results are not conclusive and in part contradictory.

CONCLUSION

Possibly due to the high variance in methodological approaches of the studies it is not possible to identify a specific weather condition associated with a generally higher risk for suicide. Weather and seasonal effects may interact with each other. Environmental effects on brain function and weather-related interactions of people may be involved in the occurrence of suicidal behaviour.

Climatic and diurnal variation in suicide attempts in the ED

The aim of this study was to determine whether there is a relationship between climatic factors and suicidal behavior. A total of 1,119 suicide attempts were collected from hospital records between 1996 and 2001. A clear seasonal variation was seen in suicide attempts in the 15-24, 25-34, and over 65 age groups in men and in the 15-24, 25-34, and 35-44 age groups in women with peaks in the spring and summer. Suicide attempts were more frequent between the hours of 6:00-9:00 pm in males and 3:00-6:00 pm in females. People attempting suicide who have depression, anxiety, or a psychotic disorder usually attempt suicide in the summer. Whereas the monthly averages of humidity, ambient temperature, duration and intensity of sunlight were positively correlated with the number of monthly suicide attempts, cloudiness and atmospheric pressure were negatively correlated. In conclusion, we must keep in mind that suicides and suicide attempts are not only the effect of climatic changes and that the most important component is the individual's ability to deal with conflicts.

Seasonal variation and meteotropism in suicide: clinical relevance of findings and implications for research

Seasonal asymmetry in yearly suicide occurrence is a long-observed phenomenon in psychiatric, suicidological and sociological research, and the effects of seasonal factors on suicidal behaviour have been the focus of a number of earlier studies. Taking into account limitations of data and methods, these studies have in general favoured interpretations based on psychosocial factors. Recent studies have challenged the widely held notion that seasonal effects on suicide are not influenced by age, gender or the circumstances of the act. The suicides committed with violent methods have been shown to follow clearer seasonal patterns than suicides by less violent methods, and differences have been found between male and female cycles of occurrence. The seasonal occurrence of suicides has also been found to differ significantly between the young and the elderly. The use of inappropriate statistics or age- and gender-biased samples may have hidden a seasonal component in some previous studies on attempted suicide. The absence of seasonality in earlier studies on attempted suicide was interpreted as depending upon the minor relevance of psychiatric and biological factors in non-fatal self-harm. However, recent studies have reported clear seasonality in attempted suicide samples, with older people showing greater seasonal effect. Recent literature after 1985 on seasonal variation and weather or climate influence in attempted and completed suicide is reviewed. Suggestions for research and the development of more effective preventative strategies are offered.

Season and suicide: recent findings from Italy

Seasonal asymmetry in yearly suicide occurrence is a long-observed phenomenon in psychiatric, suicidological, and sociological research, and the effects of seasonal factors on suicidal behavior have been the focus of a number of earlier studies. Taking into account limitations of data and methods, these studies have generally favored interpretations based on psychosocial factors. Recent studies have challenged the widely held notion that seasonal effects on suicide are a unitary phenomenon, not influenced by age, gender, or circumstances of the act. In particular, the seasonal occurrence of suicides has been found to differ significantly between the young and the elderly, and differences have also been found between male and female cycles of occurrence. Suicides using violent methods have been shown to follow clearer seasonal patterns than suicides by less violent methods (such as drug or gas poisoning), possibly reflecting the greater impulsive component involved in the choice of a violent lethal means. In this paper, findings from Italy are used to illustrate the clinical implications of studies into the topic of season and suicide, with the aim of developing more effective preventative strategies.

Teenage attempted suicide in Hong Kong

We examined the epidemiological profiles and characteristics of suicide attempters admitted to the Accident and Emergency Department of a regional hospital in Hong Kong (Princess Margaret Hospital) in the period from January to December 1995. These consisted of 101 adolescents (16 males and 85 females) aged between 10 to 24 years. There were significantly more female attempters than males, especially in the group aged 10-19, which had a male-to-female ratio of suicide rates of 1:11. Most of the methods used were nonlethal; the attempters were not serious enough and had no real intention to die. The use of painkillers and sleeping pills was most common. The main precipitating factor was interpersonal problems, for example, relationships, spousal and parental problems, especially among teenage girls. More than 90% of the cases stayed at the hospital for further observation, the mean length of stay in the hospital being 3.3 days. The potential health cost to the hospital system was around HK $11.7 million. Underestimating the prevalence of attempted suicides in Hong Kong could be a serious matter.

Suicide in Hong Kong 1971-1990: age trend, sex ratio, and method of suicide

This study gives an overview of the suicide rates in Hong Kong in the last 2 decades (1971-1990). It was found that the average suicide rate for the whole population was 11.3 per 100,000 population and it has been quite steady in recent years. The male and female adolescent (age-group 10-24 years) suicide rates were approximately the same, while the ratio of the overall male to female rate was 1.3:1. This indicated a relatively high female rate as compared with other countries. An examination of the suicide rates for various age-groups showed that the rate increased with age. The adolescent suicide rate was not particularly high (4.7 per 100,000 population for the age-group 10-24 years), but that for the elderly was 4-5 times the overall rate (49.5 per 100,000 population for those aged over 70 years). As regards the method of suicide, jumping from a height and hanging predominated in all age-groups. These methods were in great contrast to those used in other countries.