| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Psychiatric Bulletin | Advances in Psychiatric Treatment | All RCPsych Journals |
|
|
|
||||||||||
|
||||||||||||
Department of Psychological Medicine, Institute of Psychiatry, London
Public and Environmental Health Research Unit, London School of Hygiene and Tropical Medicine, London, UK
Correspondence: Lisa A. Page, Room 3.14, Department of Psychological Medicine, Institute of Psychiatry, King’s College London, Weston Education Centre, London SE5 8RJ, UK. Tel: +44 (0) 20 7848 5289; fax: +44 (0) 20 7848 5408; email: l.page{at}iop.kcl.ac.uk
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
Aims To assess the relationship between daily temperature and daily suicide counts in England and Wales between 1 January 1993 and 31 December 2003 and to establish whether heatwaves are associated with increased mortality from suicide.
Method Time-series regression analysis was used to explore and quantify the relationship between daily suicide counts and daily temperature. The impact of two heatwaves on suicide was estimated.
Results No spring or summer peak in suicide was found. Above 18 °C, each 1 °C increase in mean temperature was associated with a 3.8 and 5.0% rise in suicide and violent suicide respectively. Suicide increased by 46.9% during the 1995 heatwave, whereas no change was seen during the 2003 heat wave.
Conclusions There is increased risk of suicide during hot weather.
|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
More generally there is evidence of a U-shaped relationship between mean temperature and all-cause mortality (Curriero et al, 2002), with (for example) minimum all-cause mortality in London occurring at 19 °C (Hajat et al, 2002). During extremes of high temperature (i.e. heatwaves) increases in daily mortality have been clearly documented (Kovats & Ebi-Kristie, 2006), but this effect has not been specifically investigated for suicide before. Our aims were first to assess the relationship between daily suicide counts and daily temperature, and second to assess the impact of specific heatwave episodes on suicide.
|
|
METHOD |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
The UK Office for National Statistics (ONS) provided mortality data on all deaths considered due to suicide between 1 January 1993 and 31 December 2003 in England and Wales. All deaths that occurred before 31 January 2000 were coded using ICD–9 codes (World Health Organization, 1978); thereafter ICD–10 codes were used (World Health Organization, 1992). Deaths assigned to the following codes were included: ICD–9 codes E950.0–E959.0, E980.0–E989.0 (excluding E988.8); ICD–10 codes X60–X84, Y10–Y34 (excluding Y33.9). Deaths recorded as being due to ‘undetermined intent’ were included in the study. For each death information was available on date of death, gender and method. Suicides were classified as ‘violent’ or ‘non-violent’ depending on the method used and in line with previous studies – see, for example, Maes et al (1994). Self-poisonings by solid, liquid or gas were classed as ‘non-violent’ suicide and all other methods were considered ‘violent’. A small number (n = 11) of ICD–9 coded deaths were classified as being due to ‘late effects’ of either self-inflicted injury or assault; these were discarded from the analysis as date of death might not have been close in time to the date of injury.
The Met Office (http://www.metoffice.gov.uk) provided central England temperature data for the period under study; these include daily maximum and minimum temperatures collated from readings at four monitoring stations in central England (Parker et al, 1992). Daily mean temperature was calculated from the average of the maximum and minimum temperatures. Duration of daylight for each day of the year was obtained for London from the website http://www.sunrisesunset.com.
Analysis strategy
All analyses were performed using Stata version 8.2 for Windows. The data
were collapsed into daily counts of suicide, violent suicide and non-violent
suicide for each date in the series. Basic description of the data was
undertaken prior to graphical examination of suicide trends by season and over
the entire time period.
Generalised linear modelling
The relationship between death counts and mean temperature was explored
using Poisson generalised linear modelling. The initial strategy was to
include potential time-varying confounders in a model that excluded
temperature. Confounders were identified as follows:
Graphs showing deviance residuals between the model residuals and daily lag were produced to allow for assessment (and correction if needed) of autocorrelation within the data. Autocorrelation refers to consecutive days having non-independent suicide counts. An overdispersion parameter was calculated from the model by dividing the variance by the mean; overdispersion is taken to be absent or minimal if the parameter approaches 1.
Mean temperature was subsequently added into the model to estimate the effect of temperature on suicide counts after adjustment for all known time-varying confounders. Natural cubic splines were first used to assess visually the functional form of the adjusted relationship, thereby identifying whether the relationship was likely to be linear or not across the full range of temperatures. Natural cubic splines set ‘knots’ at regular intervals along the exposure variable (temperature) allowing the adjusted relationship between temperature and death counts to be assessed for each inter-knot segment. Following visual assessment of the relationship, linear terms could then be used for quantification of the effect for each inter-knot segment. The main outcomes of interest were all suicides, violent suicides and non-violent suicides. Secondary outcomes of interest were male and female suicides. Men are more likely to use violent methods of suicide (Maes et al, 1993), so it was predicted that male suicides would demonstrate a different temperature effect to female suicides. All age groups were considered together in order to retain power.
Episode analysis
An ‘episode analysis’ was undertaken to assess the effect of
two separate heatwaves on daily suicide counts. Our hypothesis was that if
high ambient temperatures were associated with higher death counts, then
sustained periods of unusually high ambient temperature (i.e. heatwaves) would
result in higher counts than is usual for that time of year. All suicide cases
(rather than suicide subgroups) were used for the episode analysis because of
the relatively few number of deaths on individual days. The two heatwave
periods in the data-set were 30 July to 3 August 1995
(Rooney et al, 1998)
and 4 August to 13 August 2003 (Johnson
et al, 2005b); these periods were defined as
starting when the maximum central England temperature surpassed average values
by 8 °C and ending when temperatures returned to average (Met Office
data). Expected mortality from suicide for the same calendar periods was
calculated by averaging the counts from the nearest four years in the data-set
for the 1995 heatwave (1993, 1994, 1996 and 1997) and for the 2 years prior to
the 2003 heatwave (2001 and 2002). In view of the declining number of suicides
after 2001, it was judged that to use years that preceded 2001 in the episode
analysis of the 2003 heatwave might risk underestimating any effect of the
heatwave. A 7-day moving average count was used to militate against a
‘day of week’ effect. Percentage excess mortality was then
calculated as follows, with calculation of confidence intervals obtained by
assuming a Poisson distribution.
|
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
Temporal trends
Graphical display of the data showed that the number of suicides per year
was relatively consistent between 1993 and 2000, albeit with a gradual rise in
violent suicides. Between 2001 and 2003 there appeared to be a reduction in
yearly numbers of both violent and non-violent suicide and this is in line
with recent ONS findings (Office for
National Statistics, 2005). The highest monthly number of suicides
(both violent and non-violent suicides) took place in January. This finding
remained after monthly counts were adjusted for number of days in the month.
Examining the data using a time-series plot averaged across 1 year shows that
daily suicide counts remained fairly consistent until the beginning of
November, when counts started to diminish
(Fig. 1). Similar plots were
observed for violent and non-violent suicide (data not shown).
|
Regression analysis
The use of natural cubic splines allowed the adjusted relationship between
suicide counts and temperature to be modelled across the range of
temperatures. A natural cubic spline model offered a better fit to the data
than a linear term (likelihood ratio test 46.21, P< 0.0001),
implying that the adjusted relationship between temperature and suicide was
significantly non-linear across the whole range of temperature. Spline
functions demonstrated subtly different profiles for all suicide, violent
suicide and non-violent suicide; however, in all three groups there was
evidence of increasing risk at higher temperatures
(Fig. 2). For all suicides and
violent suicides there was visual evidence of a high temperature threshold
effect at approximately 18 °C, i.e. a ‘hockey stick’ plot was
seen, with the gradient of the line becoming steeper above this temperature. A
similar temperature threshold could be seen for non-violent suicide, although
the estimate was less precise (as indicated by wider confidence intervals) and
the overall gradient was flatter. When deaths recorded as being due to
‘undetermined intent’ were excluded from the analysis, the
estimate did not substantially change. There was no evidence of significant
autocorrelation within the data (when deviance residuals were plotted,
autocorrelations were <0.05 within a 7-day lag), therefore no control for
autocorrelation was made in subsequent analyses. Overdispersion was
approximately 1.06 for all the suicide models, which was considered adequate
without further correction. Modelling an interaction between daylight and mean
temperature failed to give a better fit to the data (likelihood ratio test
1.68, P=0.640), indicating that there was no statistical interaction
between these two variables.
|
|
The effect of high ambient temperature on male and female suicide counts was estimated in a secondary analysis. The natural cubic spline plots (Fig. 2) show that the relationship between temperature and suicide is similar for male suicide and all suicides. The plot for female suicide appears to demonstrate a shallower curve than that for male suicide, with a steady positive gradient from approximately 15 °C. The percentage increase in suicide counts above 18 °C was similar for both genders, although the estimate was less precise for women.
Episode analysis
There were mixed results from the analysis of the heatwave events. The 1995
heatwave was associated with a marked short-term increase in mortality from
suicide, whereas the 2003 heatwave was associated with virtually no change in
mortality (Table 2,
Fig. 3). In a post hoc
attempt to explore the possible reasons for this lack of effect during the
2003 heatwave, the month prior to the 2003 heatwave was examined graphically.
This demonstrated that there might have been an increase in mortality during
an earlier hot spell between 13 July and 17 July, when mean temperatures
increased to over 19 °C for four consecutive days
(Fig. 3). This brief heatwave
in July 2003 might have resulted in some immediate increase in mortality, as
reported in Table 2, although
the confidence intervals were wide and encompassed zero.
|
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
A large data-set was used for this study, which covered all deaths registered as being due to suicide in England and Wales between 1993 and 2003. The mortality and meteorological data were gathered as part of routine surveillance work by ONS and the Met Office and were unlikely to have been influenced by observer bias. The high quality of data provided by the death registration process in the UK meant that it was feasible to include ‘undetermined intent’ deaths as suicides in the study, which maximised the power of the study to detect an effect. Time-series analysis is a powerful technique with which to explore longitudinal data such as these, with the major advantage that it is not necessary to know the population denominator or the distribution of known (or unknown) individual risk factors within the population to interpret the findings. The ecological design of the study means that it is impossible to ascribe heat-related mechanisms to deaths occurring at times of high ambient heat, because individual exposure to high temperature was not known. Nevertheless, during hot periods it is highly likely that those who died were, like the majority of the population, exposed to high temperatures. The scarcity of air-conditioning in the UK means it is unlikely that many of those who died were able to keep themselves cool at times of great heat.
Lack of evidence for seasonality
The results of our study did not support the finding of a spring or summer
peak in deaths from suicide; suicide occurred most frequently in January.
Neither was a seasonal effect seen for violent suicide, which has been
identified as the subtype of suicide most likely to be associated with season
(Maes et al, 1993;
Hakko et al, 1998;
Preti & Miotto, 1998;
Rasanen et al, 2002;
Rock et al, 2003).
Although the majority of previous European studies have shown a spring or
summer peak in suicide, studies from the UK in the recent past have not. In
particular, two studies that used ONS data for England and Wales between 1982
and 1999 found no – or very little – evidence of a seasonal effect
(Yip et al, 2000;
Simkin et al,
2003).
Harmonic analysis, an alternative time-series technique, has been shown to increase the likelihood of finding a seasonal effect for suicide (Hakko et al, 2002). However, harmonic analyses were used by Yip et al (2000) and Simkin et al (2003), who both failed to show any significant seasonality within recent UK data. It therefore seems unlikely that the choice of analysis technique has influenced the findings in this case. One explanation is that the effect of seasonality has become less important in recent decades in some countries (Yip et al, 2000; Ajdacic-Gross et al, 2005). Chew & McCleary (1995) looked at seasonality and suicide in 28 countries and found that countries with high levels of industrialisation and low numbers involved in agricultural work showed the least seasonality.
Effect of temperature on suicide counts
Despite no evidence of a seasonal effect on suicide, it was possible to
show that temperature has a short-term effect on suicide counts. By modelling
the relationship of temperature to death counts using natural cubic splines, a
high temperature threshold was determined above which the effect of
temperature increased linearly. This technique has not been used to study
deaths from suicide before, although when used in other contexts has shown
similar high temperature effects for hospital admissions for renal and
respiratory problems (Kovats et
al, 2004) and total mortality
(Hajat et al, 2002).
The relationship between suicide and mean temperature demonstrates a similar
threshold to that of total mortality and temperature, which has been estimated
to occur at about 19 °C (Hajat et
al, 2002). This is the first time that death from suicide has
been shown to be contributing to the known increase in all-cause mortality at
higher temperatures.
The effect of high temperature on death counts was seen for all subtypes of suicide except non-violent suicide, for which the evidence was weaker. In real terms this finding is likely to be important, as the relative risk estimates for each degree of temperature above 18 °C indicate an increase in suicide and violent suicide of 3.8 and 5.0% respectively. It is not infrequent for the mean temperature in England to be above 18 °C, with such values being recorded on 222 days over the 11-year period of the study. It is unlikely that deaths from suicide are merely being brought forward in time (or ‘harvested’) during hot weather – real additional suicides probably occur when temperatures are high. Future research should focus on whether other important subgroups, such as the elderly, are disproportionally affected by suicide in hot weather.
The 1995 heatwave resulted in a clear excess of suicide during the period of hot weather: the increase of 41.5% is well in excess of the 10.8% increase in all-cause mortality reported for the same period in London (Kovats et al, 2004). The absence of effect during the 2003 heatwave is therefore surprising and an explanation is required. Heatwaves that occur in early summer have been found to result in greater all-cause mortality than those that occur later in the year, implying that people most vulnerable to heat-related death may die during early periods of high temperature and/or that some adaptation to high temperature can occur (Basu & Samet, 2002). It is possible that both of these mechanisms were important during the 2003 heatwave. The earlier period of hot weather between 13 July and 17 July 2003 might have resulted in some excess deaths in those most susceptible to heat-related suicide, while also allowing some physiological or behavioural adaptation among other vulnerable individuals. The later heatwave in August 2003 may therefore have resulted in fewer deaths than would otherwise have occurred. This implies that a sudden increase in temperature may result in greater mortality from suicide than a gradual and sustained increase.
Study limitations
Because of the ecological design of the study it was impossible to link
individual (or community) characteristics to heat-related suicide. Additional
limitations of the study were potential misclassifications of outcome and
exposure, which could have led to some bias in the results. First, deaths from
the whole of England and Wales were used in the study and yet the temperature
measure (the exposure of interest) was taken from four monitoring stations in
central England. Second, it was not known exactly when the suicidal act took
place, as only date of death was available for analysis. Third, it was assumed
that there was no systematic difference between deaths designated as
‘undetermined intent’ and those recorded as clear cases of
suicide. Finally, there were missing data for a few deaths in 1993 and 1994,
although these were a small proportion of the total data-set and also unlikely
to vary systematically across the year.
Mechanism of effect
It is rarely possible to ascertain causal effects using an ecological study
design and the evidence presented here is insufficient to make the assumption
that high temperature directly causes death by suicide. However, there are
three obvious mechanisms by which high temperature could exert a causal effect
on suicides: sociological, biological and psychological. Sociological
explanations suggest that the pattern and intensity of social behaviours are
influenced by climatic variables and that it is these social interactions that
precipitate suicide (Durkheim,
1951). One possible sociological mechanism is the use of excess
alcohol on hot days; besides this, it is difficult to see how temperature
could affect social interaction to any great extent once seasonality, day of
the week and holidays have been accounted for. Unfortunately, information on
population alcohol consumption was not available for inclusion in our model,
so we cannot comment further on this potential mechanism. Biological
mechanisms have focused on neurotransmitters such as serotonin
(Mann, 2000), which are known
to vary with season and be negatively correlated with impulsivity, aggression
(Maes et al, 1995)
and suicidality (Mann, 2000).
However, it remains to be seen whether high ambient temperature could interact
with serotonin metabolism in the short term to produce an effect on suicide
counts. Although speculative, perhaps the most promising mechanism to link
suicide with high temperatures is a psychological one. High temperatures have
been found to lead individuals to behave in a more disinhibited, aggressive
and violent manner (Anderson,
1989), which might in turn result in an increased propensity for
suicidal acts. The finding that violent suicide showed the strongest
temperature effect adds some support to this putative mechanism. There was
little evidence of a lag effect in the data (results not shown), meaning that
high temperatures did not appear to have a delayed effect on increasing
suicide counts. This suggests that any causal mechanism linking increased
temperature to higher suicide counts is likely to be acting immediately.
Implications
Suicide is an important, preventable cause of premature mortality. This
study has shown an effect of high temperatures on suicide counts that will
probably become more important as global warming continues
(Patz et al, 2005).
It is possible that the population of England and Wales will adjust to higher
ambient temperatures, although the speed of global warming may be too great
for adaptation to occur. Those with mental illness are highlighted as an
at-risk group in England’s heatwave plan
(Department of Health, 2005),
although this is because of their increased susceptibility to heat stroke
(Bark, 1998) rather than for
suicide prevention. In any case, it remains to be seen whether public health
measures (designed after the 2003 heatwave) to prevent heat-related death have
been effective or not (Kovats &
EbiKristie, 2006).
Replication of these findings is required in other populations and geographical regions. Seasonal effects of suicide have been shown most consistently in northern European countries and it is not known whether there is an effect of temperature on suicide in other regions (e.g. equatorial countries) where high temperatures are more common. If a consistent association between short-term high temperature and suicide is identified, further attention needs to be paid to the mechanisms that underlie this effect.
|
|
ACKNOWLEDGMENTS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
|
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
|---|
Anderson, C. (1989) Temperature and aggression: ubiquitous effects of heat on occurrence of human violence. Psychological Bulletin, 106, 74 –96.[CrossRef][Medline]
Bark, N. (1998) Deaths of psychiatric patients
during heat waves. Psychiatric Services,
49, 1088
–1090.
Basu, R. & Samet, J. (2002) Relation
between ambient temperature and mortality: a review of the epidemiological
evidence. Epidemiologic Reviews,
24, 190
–202.
Chew, K. & McCleary, R. (1995) The spring peak in suicides: a cross-national analysis. Social Science and Medicine, 40, 223 –230.[CrossRef][Medline]
Curriero, F., Heiner, K., Samet, J. M., et al
(2002) Temperature and mortality in 11 cities of the Eastern
United States. American Journal of Epidemiology,
155, 80
–87.
Department of Health (2005) Heatwave. Plan for England. Protecting Health and Reducing Harm from Extreme Heat and Heatwaves. UK Department of Health.
Durkheim, E. (1951) Suicide. The Free Press.
Hajat, S., Kovats, R. S., Atkinson, R. W., et al
(2002) Impact of hot temperatures on death in London: a time
series approach. Journal of Epidemiology and Community
Health, 56, 367
–372.
Hakko, H., Rasanen, R. & Tiihonen, J. (1998) Secular trends in the rates and seasonality of violent and nonviolent suicide occurrences in Finland during 1980–95. Journal of Affective Disorders, 50, 49 –54.[CrossRef][Medline]
Hakko, H., Rasanen, P. & Tiihonen, J. (2002) Use of statistical techniques in studies of suicide seasonality, 1970 to 1997. Suicide and Life-Threatening Behaviour, 32, 191 –208.[CrossRef]
Jessen, G., Steffensen, P. & Jensen, B. (1998) Seasons and meteorological factors in suicidal behaviour. Archives of Suicide Research, 4, 263 –280.[CrossRef]
Johnson, H., Brock, A., Griffiths, C., et al (2005a) Mortality from suicide and drug-related poisoning by day of the week in England and Wales, 1993–2002. Health Statistics Quarterly, 27, 13 –16.[Medline]
Johnson, H., Kovats, R. S., McGregor, G., et al (2005b) The impact of the 2003 heat wave on mortality and hospital admissions in England. Health Statistics Quarterly, 25, 6 –11.[Medline]
Kovats, R. S. & Ebi-Kristie, L. (2006)
Heatwaves and public health in Europe. European Journal of Public
Health, 16, 592
–599.
Kovats, R. S., Hajat, S. & Wilkinson, P. et al
(2004) Contrasting patterns of mortality and hospital
admissions during hot weather and heat waves in Greater London,UK.
Occupational and Environmental Medicine,
61, 893
–898.
Lester, D. (1979) Temporal variation in suicide
and homicide. American Journal of Epidemiology,
109, 517
–520.
Linkowski, P., Martin, F. & de Maertelaer, V. (1992) Effect of some climatic factors on violent and non-violent suicides in Belgium. Journal of Affective Disorders, 25, 161 –166.[CrossRef][Medline]
Maes, M., Cosyns, P., Meltzer, H. Y., et al
(1993) Seasonality in violent suicide but not in nonviolent
suicide or homicide. American Journal of Psychiatry,
150, 1380
–1385.
Maes, M., De Mayer, Thompson, P., et al (1994) Synchronized annual rhythms in violent suicide rate, ambient temperature and the light-dark span. Acta Psychiatrica Scandinavica, 90, 391 –396.[Medline]
Maes, M., Scharpe, S., Verkerk, R., et al (1995) Seasonal variation in plasma L-tryptophan availability in healthy volunteers. Relationships to violent suicide occurrence. Archives of General Psychiatry, 52, 937 –946.[Abstract]
Mann, J. J. (2000) The neurobiology of suicide. Nature Medicine, 4, 25 –30.[CrossRef]
Morselli, E. (1881) Suicide: An Essay on Comparative Moral Statistics, Paul & Co.
Office for National Statistics (2005) UK Suicides Reach 30 Year Low in 2003. http://www.statistics.gov.uk/pdfdir/suicide0305.pdf
Parker, D., Legg, T. & Folland, C. K. (1992) A new daily Central England Temperature series, 1772–1992. International Journal of Climatology, 12, 317 –342.[CrossRef]
Patz, J., Campbell-Lendrum, D. Holloway, T., et al (2005) Impact of regional climate change on human health. Nature, 438, 310 –317.[CrossRef][Medline]
Petridou, E., Papadopoulos, F., Frangakis, C., et al (2002) A role of sunshine in the triggering of suicide. Epidemiology, 13, 106 –109.[CrossRef][Medline]
Preti, A. (2000) Seasonal variation and meteotropism in suicide. Current Opinion in Psychiatry, 13, 655 –660.[CrossRef]
Preti, A. & Miotto, P. (1998) Seasonality in suicides: the influence of suicide method, gender and age on suicide distribution in Italy. Psychiatry Research, 81, 219– 231.[CrossRef][Medline]
Rasanen, P., Hakko, H., Jokelainen, J., et al (2002) Seasonal variation in specific methods of suicide: a national register study of 20 234 Finnish people. Journal of Affective Disorders, 71, 51 –59.[CrossRef][Medline]
Rock, D., Greenberg, D. & Hallmeyer, J. (2003) Increasing seasonality of suicide in Australia 1970–1999. Psychiatry Research, 120, 43 –51.[CrossRef][Medline]
Rooney, C., McMichael, A., Kovats, R., et al (1998) Excess mortality in England and Wales, and in Greater London, during the 1995 heatwave. Journal of Epidemiology and Community Health, 52, 482 –486.[Abstract]
Salib, E. & Gray, N. (1997) Weather
conditions and fatal self-harm in North Cheshire 1989–1993.
British Journal of Psychiatry,
171, 473
–477.
Schwartz, J., Spix, C., Touloumi, G., et al (1996) Methodological issues in studies of air pollution and daily counts of deaths or hospital admissions. Journal of Epidemiology and Community Health, 50 (suppl. 1), S3 –S11.[Medline]
Simkin, S., Hawton, K., Yip, P. S., et al (2003) Seasonality in suicide: a study of farming suicides in England and Wales. Crisis, 24, 93 –97.[Medline]
Souetre, E., Salvati, E., Belugou, J. L., et al (1987) Seasonality of suicides: environmental, sociological and biological covariations. Journal of Affective Disorders, 13, 215 –225.[CrossRef][Medline]
World Health Organization (1978) International Statistical Classification of Diseases and Related Health Problems (ICD–9). WHO.
World Health Organization (1992) International Statistical Classification of Diseases and Related Health Problems (ICD–10). WHO.
Yip, P., Chao, A., & Chiu, C. (2000)
Seasonal variation in suicides: diminished or vanished. Experience from
England and Wales, 1982–1996. British Journal of
Psychiatry, 177, 366
–369.
Received for publication October 4, 2006. Revision received March 22, 2007. Accepted for publication March 30, 2007.
Related articles in BJP:
This article has been cited by other articles:
|
|
 |
|
  E. Salib, M. Cortina-Borja, and D. Anderson Hot weather and suicide: a real risk or statistical illusion? The British Journal of Psychiatry, December 1, 2007; 191(6): 560 - 560. [Full Text] [PDF]
|
|
Read all eLetters
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Psychiatric Bulletin | Advances in Psychiatric Treatment | All RCPsych Journals |
