University of Newcastle upon Tyne, Newcastle upon Tyne
Correspondence: Dr K. Schapira, 4 Brookfield, Westfield, Gosforth, NE3 4YB, UK. E-mail: kurt.schapira{at}ncl.ac.uk
See pp.465468, this
issue.
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ABSTRACT |
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Aims To study causes of change in suicide rate over a 30-year period in Newcastle upon Tyne.
Method Suicide rates and methods, based on coroners' inquest records, were compared over two periods (1961-1965 and 1985-1994) and differences were related to changes in exposure to poisions and prescribed drugs, and to socio-demographic changes.
Results Demographic and social changes had taken place which would adversely affect suicide rates. However, a dramatic fall was found in the rate for women, and a modest decline in that for men. Reduced exposure to carbon monoxide and to barbiturates coincided with the fall in rates.
Conclusions Reduced exposure to lethal methods was responsible for the fall in rate in both genders, while the gender difference in favour of women may be related to their preference for non-violent methods or to their being less affected by the social changes.
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INTRODUCTION |
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METHOD |
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Statistics
Comparisons of continuous variables using Student's t were
undertaken only after Kolmogorov-Smirnov tests had indicated that data
distribution did not differ significantly from normality. Categorical
variables were subjected to chi-square analysis with continuity correction,
although in several cases (Tables
1 and
2) this was based on very small
sample sizes and caution is therefore required in interpretation of the data.
Statistical analysis was undertaken with SPSS for Windows 8.0 and relative
risks and confidence intervals were calculated using EPInfo 6.0 software
(Dean, 1995). Logistic
regression was performed, with period (A or B) as the dependent variable to
determine which variables contributed significantly to the model predicting
group membership. Cohen's statistic was calculated to measure the
agreement between observed and predicted membership.
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RESULTS |
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Figure 1 shows the number of suicides occurring in Newcastle during the period 1960-1995, calculated as a rolling 3-year average. Coal gas was replaced by nontoxic domestic gas early in 1974. Changes of coroner are also shown. The fall in suicides began in the early 1980s in both genders.
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Civil status
There have been significant changes in the distribution of suicide by civil
status. In Table 2, to allow
comparison with population figures for 1961-1965
(General Register Office,
1963a) and for 1985-1994
(Office of Population Censuses and
Surveys, 1992a), a person cohabiting or living with a
partner is classed as single and a separated person as married. The percentage
of single persons among suicides has risen from 19% to 39% and of divorced
persons from 4% to 14%, while that of married persons has decreased from 57%
to 30% (2=28.8, d.f.=3, P<0.001). Because of
changes in marital status in the general population, the actual rate
in single men shows little change, while in single women the rates have fallen
by 50%. The increase in the number of divorces in the general population
resulted in the suicide rates in divorced persons falling dramatically. The
relative risks attached to civil status among the suicides and in the general
population are shown in Table
3.
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Unemployment and retirement
There were 19 unemployed men and 6 unemployed women among suicides in
period A and 26 unemployed men and 3 unemployed women in period B.
Unemployment in the general population of Newcastle had increased during the
period 1961-1991 from 2880 to 12673 among men, and from 800 to 5014 among
women (General Register Office,
1966; Office of Population
Censuses and Surveys, 1992b), and the suicide rate among
unemployed persons had fallen from 131.9 to 20.5 per 100 000 in men and from
150.0 to 6.0 per 100 000 in women. The relative risks show that unemployment
among suicides remained significantly increased in period B compared with the
general population in men, but not in women
(Table 3). A similar situation
existed concerning retirement, which continued to be a risk factor in period B
in men but not in women (Table
3).
Residence
There was a significant change in place of residence among suicides in both
genders, with proportionately more in hostels, sheltered homes and
institutions and fewer in psychiatric hospitals or living with others in the
community. More of the women were living alone. As the number of people living
alone in the whole population had increased almost threefold (from 13643 to
37068) (General Register Office,
1963b; Office of
Population Censuses and Surveys, 1992d), the actual
suicide rate among those living alone had fallen markedly. Despite this,
living alone remained a significant risk factor
(Table 3). The relative risk of
being a psychiatric hospital in-patient or a resident in a hostel or sheltered
accommodation was significantly raised in period B
(Table 3). The number of
suicides who were psychiatric in-patients at the time of suicide increased
despite the fall in the hospital population. Of the 24 suicides who were
currently resident in sheltered accommodation (10) or were hospital inpatients
(14), four were in period A and 20 in period B, a significant difference
(2=11.92, d.f.=1, P=0.001).
Mode of suicide
Table 4 compares the number
of suicides in each period, by method and gender. The tests of significance
refer to differences between periods. In period A, 94% of carbon monoxide (CO)
deaths were due to domestic gas, whereas in period B deaths from gas were
entirely due to car exhausts. Neither selective serotoin reuptake inhibitors
(SSRIs) nor paracetamol were available in the earlier period but, whereas
paracetamol was frequently used later, no suicide was associated with SSRIs;
moreover, there was no case of overdose with an SSRI among those admitted to
the intensive treatment unit (ITU) in Newcastle in period B. Other substances
were mostly drugs such as codeine, coproxamol and anticholinergics, but
included poisons such as paraquat and phenol. In period B, the most commonly
used substances in combination were paracetamol, anxiolytics, antidepressants
and codeine, and less frequently salicylates, anticholinergics and insulin; 15
had taken alcohol, but this is similar in proportion to the group as a whole.
Violent methods of all kinds, particularly hanging, increased in period B.
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Psychiatric morbidity
Sixty-four subjects (41%) had received psychiatric in-patient treatment at
some time in their lives in period A and 38 (27%) in period B a
significant difference (2=6.72, d.f.=1, P=0.14)
while the number of those who had never received psychiatric treatment
decreased from 46% to 39%; the remainder had obtained out-patient or general
practitioner treatment. Fourty-four subjects in period A and 61 in period B
had made previous suicide attempts, of whom 12 and 26, respectively, had made
more than one (
2=9.59, d.f.=2, P<0.01); the
difference was significant only in men.
Multivariate analysis
Logistic regression was carried out with period as the dependent variable.
All those variables, entered both singly or as a group, that had significant
P values (P<0.05) based on the Wald statistic, were then
entered in four blocks: throughout age/gender, socio-demographic, psychiatric
morbidity and methods. Using the forward stepwise method, the overall
predictions of group membership (period A or B) with a cut point of 50%, were
compared at each step, and Cohen's calculated. Baseline prediction was
52.3%. Age and gender increased prediction to 57.2% (
=0.47), with
gender (P=0.007) but not age making a significant contribution. Both
gender and age remained in the analysis, showing that the significant
associations with other variables were not explained by gender or age
differences between the periods. With the socio-demographic variables (being
single, divorced or retired), prediction was 69.9% with
of 0.391.
(When married was substituted for single divorced, prediction was 64.7% and
=0.293.) Addition of the three psychiatric variables (history of
in-patient care, psychiatric history, previous suicide attempts) together
increased prediction to 70.9% (
=0.414). The addition of methods
poisoning by CO, barbiturates, salicylates and combinations of drugs
increased prediction to 83.6% (
=0.671). The four methods entered alone
gave 80.7% prediction and a Cohen's
of 0.612. Other methods (poisoning
by paracetamol or other substances, hanging and jumping from heights) also had
significant associations with period B individually but did not improve
prediction when methods were entered as a block. Stepwise analyses were also
carried out on men and women separately. In women, prediction was 87.5% and
-0.725, but none of the socio-demographic or psychiatric variables was
significant in the presence of methods. In men, age, being divorced, retired,
a history of in-patient care, and previous attempts were all significant
(P<0.05) in the presence of methods; prediction was 80.7% and
=0.611.
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DISCUSSION |
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The purpose of the study was to compare suicide rates in two periods in Newcastle upon Tyne, with a view to identifying factors that might be responsible for a change in rates and areas where intervention might be practicable.
Demographic and social changes
Between the two periods, the population of the city of Newcastle had
undergone a dramatic increase in the number of divorced persons and a
considerable increase in that of single persons, a marked increase in the
general level of unemployment, and an exodus from psychiatric hospitals
probably associated with an increase in those living alone or in supported
accommodation. The proportion of persons aged 65 years or over had
increased.
Age, gender and civil status
Hawton (1992) drew
attention to a rise in suicide in the UK among young males, a trend
also observed throughout Europe and North America
(Diekstra, 1993), but in
Newcastle the rate among 15- to 24-year-olds remained low. Rates for older
people are more variable, usually increasing in men but decreasing in women
(Diekstra, 1993). Nearly
one-quarter of the suicides in Newcastle in both periods were aged 65 or over,
and this is the age group that is, in general, at greatest risk for completed
suicide (Cattell, 1998) and in
which diagnosis and treatment of physical illness and of major depression rank
high among potential preventative strategies available to clinicians.
Being widowed remained a significant risk factor in both genders, as did divorce in men. The increase in the number of divorced men but not women who committed suicide suggests that divorce may be more traumatic for men. The relative risk of being single became significant in period B, while being married was protective in that period (Table 3). The association of being single or divorced with period B was not merely due to the effects of changes in age and gender and it is concluded that, despite the fall in suicide rates, being single or divorced continued to identify vulnerable individuals.
Unemployment and retirement
Lewis & Sloggett (1998)
found that the association between suicide and unemployment accounted for all
or most of the association between suicide and socio-economic indices, but
they were unable to adjust for the effects of psychiatric illness. In
Newcastle, unemployment and retirement decreased in importance for both
genders over the study period, the relative risks becoming non-significant in
women. These changes suggest that when unemployment or early retirement are
comparatively uncommon they are more likely to be associated with ill-health,
whereas when they are common they are experienced by many healthy people who
are not disposed to suicide.
Living alone and social isolation
In Newcastle, the nearly threefold increase in the number living alone in
the general population was associated with a marked fall in suicide among
them, suggesting that the social disorganisation of urban areas with high
suicide rates found by Sainsbury
(1955) did not occur in
Newcastle. However, living alone was still associated with a significantly
increased risk (Table 3). At
the other end of the scale, among those hospitalised or resident in sheltered
environments, it is not surprising that the risk was greater in period B, when
only the most vulnerable remained outside the community.
Exposure and methods
Our findings indicate that the fall in suicide rates coincided with marked
changes in pattern of exposure and method.
Carbon monoxide and drugs
A fall in the suicide rate in all age groups following the abolition of
coal gas was demonstrated by Kreitman
(1976). However, poisoning by
car exhausts has recently been increasing, and accounted for some male
suicides in Newcastle. Will the enforced introduction of catalytic converters
(which reduce the CO content from car exhausts) reduce fatalities of this
kind, as it appears to have done in the USA
(Clarke & Lester, 1987)?
Suicide due to drug overdoses in England and Wales decreased in the 20 or so
years prior to 1990 (Charlton et
al, 1992). This undoubtedly reflected the changes in
prescribing practices. Oliver & Hetzel
(1973) showed that barbiturate
suicide in Australia decreased subsequent to legislation on barbiturate
prescribing, and that this decrease occurred particularly in women.
Additionally, and most importantly, overall suicide rates also
decreased, which implies that barbiturates were not entirely replaced by
increased use of other methods.
There was a significant increase in period B in the use of antidepressants. Nationally, there has been a 50% increase in prescription of tricyclics over the past 10 years compared with an increase of almost 200% for SSRIs and related antidepressants which became available in the 1980s (Department of Health, 1997). But the drugs used by those committing suicides in our study were all tricyclics. This supports the view that SSRIs are an attractive choice for treatment of depressed patients who are at risk of suicide (Edwards, 1995; Kasper et al, 1996). We also believe that the development of ITUs, which did not exist in period A and where most cases are admitted after a life-threatening overdose, may have contributed to the general fall in suicide rates. Among over-the-counter drugs, aspirin and paracetamol accounted for almost one in five cases of suicide. Paracetamol appears to have replaced salicylates not only as a widely used analgesic in both genders but also as a very effective method of suicide both alone and in combination with other drugs. From September 1998, the Royal Pharmaceutical Society of Great Britain limited the size of packs of aspirin or paracetamol to 32 tablets or capsules. Although this has been shown to have reduced the amount taken in single overdoses (Robinson et al, 2000) it remains to be seen whether this will be effective in reducing attempted or completed suicide from these drugs.
Violent methods
There was a dramatic rise in Newcastle in hanging among men, which did not
occur in women. Hanging increased in the general population in the 20 years up
to 1990 (Charlton et al,
1992), when it accounted for 38% of male and 29% of female
suicides in England and Wales (Office for
National Statistics, 1995). Cooper & Milroy
(1994) looked specifically at
violent suicides and observed that hanging was the method of choice when the
suicide was precipitated by the end of a relationship.
Relative risks and multivariate analysis
The results of the multivariate analyses have to be interpreted in the
light of the relative risks and the changes in exposure (Tables
3 and
4). The relative risks
(Table 3) show the magnitude of
the risk of suicide associated with a characteristic in comparison with its
frequency in the general population, and could be calculated only when
population data were available. The lower risks associated with divorce and
unemployment in period B are at least in part attributable to the increased
frequency of these conditions in the population. The multivariate analyses
show which variables were significantly associated with period A or B, but do
not take population changes into account. Appleby et al
(1999) in a controlled study
found mental disorder and social withdrawal among the characteristics of young
suicides. In Newcastle, socio-demographic characteristics such as being
widowed or living alone, and in men unemployment, retirement and divorce, were
found to be significant risk factors common to both periods
(Table 3). The significant
association of some of these adverse characteristics with period B, together
with under-representation of marriage with its protective effect, would by
itself predict that the suicide rate should have increased. This discrepancy
suggests the fall in rates occurred despite adverse social trends in the
community at large. Adverse social conditions are of course not always adverse
for the individual and may sometimes be beneficial; moreover, if they become
common, less-vulnerable individuals will be affected and the adverse effects
will be diluted. The smaller decline in suicide in men may perhaps be due to
the differential effects of some of these factors in men and women.
The three psychiatric variables all contributed significantly and independently to the prediction. Also, their association with period A or B probably reflects the marked changes in patterns of psychiatric care that had taken place: for instance, the increase in the numbers of patients from hospital or institutions may have been a consequence of the planned exodus into the community, resulting in the retention of only the most disturbed; and the fall in the number of suicides with a history of in-patient psychiatric treatment may have been due to the closure of hospitals and the reduction in number of beds.
The fall in suicide rates that occurred from period A to B can be most clearly related to the changes in methods of suicide, with the methods-only model producing a satisfactory level of prediction. An increase in hanging among men and in jumping from heights in women only partly nullified the effects of reduced exposure to CO and barbiturates. It seems that women choose methods of suicide that are both intrinsically less lethal and for which resuscitation is often successful, whereas men employ violent methods. This difference cannot be due to social factors alone and may be related to the greater propensity to violence in men.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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Received for publication January 17, 2000. Revision received November 6, 2000. Accepted for publication November 20, 2000.
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