This study reveals that the pattern of acute self poisoning is changing remarkably over just a few years in rural Sri Lankan districts with medicine (pharmaceutical) poisoning increasing rapidly. The population incidence of acute self poisoning was very high in this setting with young women being the most vulnerable. Although the crude country estimates of acute self poisoning appear to be similar across many low and middle income countries , there are important differences in the patterns; for example the type of poison, age and gender distribution and patient outcome. The type of poison (and consequently the lethality of deliberate self-poisoning) may vary according to accessibility of agents [11, 12]. Most of the global death toll from pesticides is in the Asian region, where many people have ready access to pesticides .
Rural Sri Lanka shares this very high incidence of pesticide poisoning. The overall population incidence of self poisoning in the Anuradhapura district of Sri Lanka (447/100,000) appears to be higher than that reported from detailed surveys in other countries. For example, it is higher than reported rates from Oxford, UK (350/100,000) , Newcastle, Australia (266/100,000) , Mashhad, Iran (390/100,000) , and Oslo, Norway (200/100,000) .
Studies from both developed and developing countries demonstrate that young people, particularly women, below 30 years are over represented in self harm [18–23]. This trend is very evident in our study; teenage girls (12–19) accounted for 21% of all poisonings. The population incidence for females aged 15 to 19 years (1226/100,000) was approximately three times higher than that for males in this age group (465/100,000). This has also been observed in other studies; for example, in the United States of America (270.8 vs. 98.6/100,000) , Australia (375 vs. 159/100,000) , and Scotland (673 vs 365/100,000) . Although female/male ratio in this study was similar to these other countries, the actual population incidence of poisoning of people aged 15 to 19 years in this area appears to be the highest reported.
The reasons for the observed higher population incidence in Sri Lanka were not within the scope of this study. Previous research in other settings in Sri Lanka [25–27] has suggested that self-poisoning is frequently impulsive [28, 29] and not associated with psychiatric illnesses. Alcoholism, relationship and financial difficulties, family disputes, physical and psychological abuse were identified as the main reasons for attempting self poisoning [25, 27]. These studies have not focused exclusively on young adults and adolescents who have self-poisoning. In the UK, this group indicated that feelings of loneliness, being unwanted, or anger were the main reasons and they used the act to alleviate or demonstrate the their distress [30, 31].
The large increase in medicinal poisoning over a short period is the most remarkable aspect of the change in self poisoning behaviour in these communities. Increased awareness within the community through media reports or other means of communication has previously led to other rapid changes in the types of poisoning [8, 32]. Common medicines such as paracetamol have been available in rural households for decades, provided as part of free health care in the country and available from local grocery shops without limitation . Therefore availability alone does not seem sufficient reason for the recent changes in the use of these drugs in self poisoning.
There has been a compensatory decrease in oleander poisoning. As pharmaceutical poisonings have a much lower mortality (Table 4) the changing pattern of ingestion may reduce the harm from self-poisoning. However, these changes have implications when allocating treatment resources and developing health policy for treatment guidelines. For example most cases of paracetamol poisoning can be successfully treated in a peripheral hospitals with antidotes such as methionine or N- acetylcysteine thereby reducing expensive hospital transfers to secondary care hospitals . Paracetamol poisoned patents who present within 10 hours of ingestion can be treated with methionine . However, this requires the antidotes to be made available in these peripheral hospitals.
Government and public health authorities also need to include drug safety and community education components to the existing awareness programs. Other strategies, such as restricting package size, or limiting the availability of non-prescription medicines like paracetamol could be implemented to reduce the severity of acute poisoning.
The observational data collected on patients was collected in the context a cluster RCT of brief educational interventions to hospital staff members to promote adherence to poisoning treatment guidelines. As the RCT had no components directed to the community there would be no expected effect on the incidence of poisoning in the community. The effects of the educational intervention if successful on mortality would likely be small and not have a substantial impact on the estimates of mortality reported in this paper.
In the referral hospital data was only collected for patients who were 12 years or above. The population data from the Department of Statistics are only available in five year age groups and has population for 10 – 14 year age group. The lack of complete poisoning data from children aged 10 and 11 years meant we could not calculate an exact population incidence for the 10 – 14 years age group. As there was a high incidence in 15–19 year age group it was important to make an estimate of incidence in the 12–14 year age group as this would be valuable in planning the timing of delivery of public health interventions. As there is population data for the 10–14 year age groups, we assumed that these populations are evenly distributed in all ages and used an estimated population for the calculation of population incidence 12 to 14 year age group.
The incidence of pesticide poisoning can change in different quarters of the year due to the season-specific agricultural activities, which have a direct relationship with pesticide availability [6, 12, 28]. As all of these areas are irrigated this minimizes seasonal impact on variation in agriculture practices and by extension variation in pesticide use which is dictated by the type of agriculture. The predominant agriculture in this region is paddy rice and domestic vegetables. With the availability of water and a paddy growing season that lasts within 3–4 months, rice is grown year round. Therefore the data collection period to describe the epidemiology and pattern of poisoning should ideally be long enough not to be affected by short term seasonal variations. The 17 months data collection period used for this study should have minimized but not completely removed such potential biases.
However, a key strength of this study was that (unlike most previous studies in Sri Lanka) it described the epidemiology and patterns of poisoning in a complete district or a geographic patient catchment area that included all the hospitals in the area. The Sri Lankan public health care network is a well established and there is a hospital for every 3–4 villages. As we found no evidence of out of hospital deaths from poisoning in coroner or police records it seems likely that most severe cases present to hospital. It is possible that less severe poisonings may not present to hospital and that our population estimates for poisoning may be an underestimate.
The agricultural patterns, health care network and socio-economic status in this district are similar to other rural areas in the country. This is more evident due to the smaller size of the country – Sri Lanka is a small country with 65610 square kilometres. Therefore we believe the epidemiological data from this study is generalizable to other rural areas of the country. And also, it is likely to be generalizable to other developing countries areas that are primarily agriculturally based. These data provided the opportunity to more accurately calculate the rural population incidence of poisoning with different substances and in different age and gender groups.