Epidemiology of intentional self-poisoning in rural Sri Lanka
Michael Eddleston
South Asian Clinical Toxicology Research Collaboration,Centre for
Tropical Medicine, University of Oxford,UK and Department of Clinical
Medicine, University of Colombo, Sri Lanka
David Gunnell
Department of Social Medicine,University of Bristol,UK
Ayanthi Karunaratne
Department of Clinical Medicine, University of Colombo
Dhammika de Silva
Office of the Provincial Director of Health Services, North Central
Province, Anuradhapura
M. H. Rezvi Sheriff
Department of Clinical Medicine, University of Colombo, Sri Lanka
Nick A. Buckley
Department of Clinical Pharmacology and Toxicology, Australian National
University Medical School, Australian Capital Territory, Australia
Correspondence:
Dr M. Eddleston, Department of Clinical Medicine, Faculty of Medicine, PO Box
271, 25 Kynsey Road, Colombo 8, Sri Lanka. E-mail:
eddlestonm{at}eureka.lk
Declaration of interest None. Funding detailed in
Acknowledgements.
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ABSTRACT
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We investigated the epidemiology of intentional self-poisoning in rural Sri
Lanka by prospectively recording 2189 admissions to two secondary hospitals.
Many patients were young (median age 25 years), male (57%) and used pesticides
(49%). Of the 198 who died,156 were men (case fatality 12.4%) and 42 were
women (4.5%). Over half of female deaths were in those under 25 years old;
male deaths were spread more evenly across age groups. Oleander and paraquat
caused 74% of deaths in people under 25 years old; thereafter
organophosphorous pesticides caused many deaths. Although the age pattern of
self-poisoning was similar to that of industrialised countries, case fatality
was more than 15 times higher and the pattern of fatal self-poisoning
different.
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INTRODUCTION
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Intentional self-poisoning is a major problem worldwide
(Hawton & van Heeringen,
2002). In industrialised countries, it predominantly occurs in
young people impulsively responding to stressful events who have little desire
to die. Deaths are rare, since the medicines ingested are of low toxicity or
easily treated. The situation is different in the developing world, where
pesticides are the most popular means of self-poisoning
(Gunnell & Eddleston, 2003)
and cause an estimated 300 000 deaths each year. Relatively little is known
about the age and gender patterns of fatal and non-fatal self-poisoning in
such regions. This study aimed to identify the poisons used in an agricultural
area of Sri Lanka, with the expectation that such knowledge will direct future
campaigns to prevent self-harm.
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METHOD
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A prospective study was established in the two secondary hospitals
(Anuradhapura and Polonnaruwa) of the North Central Province, Sri Lanka, in
2002. This agricultural region has 1.1 million people, 55% of whom are less
than 25 years old. Ethics approval was obtained from Oxford and Colombo.
Poisoned patients are first admitted to rural hospitals; around half are then
transferred to the secondary hospitals according to severity and the
facilities available. From 31 March 2002 until 15 March 2003, all patients
with self-poisoning were seen on admission by study doctors. The poison was
identified from the history, bottles, transfer letter and/or clinical
toxidrome. Blood samples were taken from 70% of patients; analysis showed that
the poison was correctly identified in over 80% of cases.
We used logistic regression models to investigate the effects of age,
gender and poison type on mortality. As no death occurred among those taking
acids, hydrocarbons or alkalis, patients taking these poisons (n=77)
were not analysed.
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RESULTS
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A total of 2189 patients with acute self-poisoning were identified over the
study period; 68 had occupational or unintentional exposure and their data are
not analysed here. Males accounted for more cases (n=1257, 57%) than
females. The overall median age was 25 years (interquartile range (IQR)
1935); female cases were younger than males: median age 21 (IQR
1729) v. 29 years (IQR 2240). The 5-year age band with
the highest number of cases was 1519 in women and 2025 in men.
The most common poisons ingested were pesticides (49%), particularly by men
(males 59%, females 35%), and oleander seeds (34%; males, 31%, females 38%).
Oleander was the poison most commonly used by females and males under the age
of 20. From age 20, pesticide ingestion became more common in both genders.
Medicines and hydrocarbons (commonly kerosene) were more often taken by women
than men (18% v. 3% and 6% v. 2%, respectively).
A total of 198 patients died, giving a case fatality ratio of 9.0%, which
was higher in males (12.4%) than in females (4.5%). Over half (52%) of female
deaths occurred in women under 25; male deaths were spread more evenly, with
only 22% of deaths occurring in men under 25
(Fig. 1). Case fatality
increased with age. In a logistic regression model controlling for gender and
type of poison taken, the risk of death increased by 62% (95% CI 4581)
per 10-year increase in age and was 52% (95% CI 4124) higher in males
than females. Oleander and paraquat were the most important cause of death in
both genders under 25 years (Fig.
1), accounting for 74% of deaths. Pesticides in general, and
organophosphates in particular, became more important thereafter, responsible
for at least 80% (organophosphates 40%) of deaths over the age of 25.

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Fig. 1 Poisons used for fatal self-poisoning by (a) males and (b) females,
according to age (HC/Ac/Alk, hydrocarbons, acids or alkalis).
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After controlling for age and gender in logistic regression models with
medicines as the reference category, the odds ratios for death among patients
poisoned by pesticides other than paraquat was 8.7 (95% CI 2.136.2), by
paraquat 102.0 (95% CI 22.8456.4) and by oleander 7.2 (95% CI
1.730.5).
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DISCUSSION
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The age-specific pattern of self-poisoning in rural Sri Lanka is similar to
that in industrialised countries: most cases occur in young people, and the
incidence peaks around age 1525 years (5 years earlier in females than
in males) and then falls steadily with increasing age (for comparison, see
Gunnell & Eddleston, 2003: Fig. 1). There are, however, a
number of important differences. Male patients outnumbered women by 1.35:1
the reverse of most other regions
(Hawton & van Heeringen,
2002). The case fatality ratio for self-poisoning patients
admitted to Sri Lankan secondary hospitals (9%) is much higher than in
industrialised countries (e.g. 0.5% in the UK). A significant number of deaths
(52% of female deaths, 11% of all deaths) occur in women under 25 years. A
similar pattern of fatal self-poisoning in young women is seen in rural areas
of China and India (Phillips et
al, 2002; Joseph et
al, 2003).
Our data were drawn from secondary hospitals and are not directly
comparable with population-based statistics. Patterns of transfer from rural
hospitals, in particular an increased tendency for transfer of men, would have
biased the pattern of admission. A preliminary study has so far found no
gender bias for transfers, nor evidence of more women dying before transfer to
the secondary hospitals. The case fatality ratio would have been lower if all
patients admitted to rural hospitals were transferred, but still several times
higher than in the West.
The substances used in fatal poisoning varied with age and with gender.
Yellow oleander was most commonly used by people under 20. Paraquat was
important in young people; after the age of 30 other pesticides (particularly
organophosphates and non-paraquat herbicides) became more important. All are
much more difficult to treat than the medicines that are commonly used for
self-poisoning in the West.
This study supports the view that organophosphate pesticides are important
causes of fatal self-poisoning in south Asia
(Roberts et al, 2003).
Paraquat and oleander may be more important in women and young people because
these substances are highly toxic and even small amounts can kill.
The case fatality ratio rose steeply with age in men and women. This may
reflect a greater level of intent in older patients, a greater use of
pesticides for self-poisoning, or a problem of comorbidity. Overall, the
higher case fatality is predominantly due to the availability of highly toxic
poisons and the difficulty of medical management. Restriction of access to
highly toxic pesticides, plus improved medical therapy and antidote
availability, could rapidly reduce the number of self-poisoning deaths in the
rural developing world.
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ACKNOWLEDGMENTS
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We thank the OxfordColombo study team and the hospitals
medical and nursing staff for their help, and Nick Bateman and Keith Hawton
for critical review. M.E. is a Wellcome Trust Career Development Fellow funded
by grant GR063560MA.
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REFERENCES
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Gunnell, D. & Eddleston, M. (2003) Suicide
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Hawton, K. & van Heeringen, K. E. (2002)
International Handbook of Suicide and Attempted
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Joseph, A., Abraham, S., Muliyil, J. P., et al
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Phillips, M. R.,Yang, G., Zhang,Y., et al
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Roberts, D. M., Karunarathna, A., Buckley, N. A., et al
(2003) Influence of pesticide regulation on acute poisoning
deaths in Sri Lanka. Bulletin of the World Health
Organization, 81, 789
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Received for publication August 16, 2004.
Revision received January 14, 2005.
Accepted for publication January 28, 2005.
eLetters:
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- Self Poisoning in Srilanka
- Sunny T Varghese, et al.
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