Background
Intentional self-poisoning (ISP; taking a purposeful overdose) results in significant morbidity and is a burden on population health. In order to reduce ISP by, for example, restricting inappropriate access to substances, information is required about which specific substances are commonly used.
Aims
I. What information about ISP can be obtained from Ministry of Health (MOH) datasets to plan poisoning prevention initiatives? What are the gaps in these data, and how could these be addressed?
II. How do emergency medicine professionals identify poisonings and investigate intent behind them, and how does that information become national hospital presentation data?
III. Which specific substances do people use in episodes of intentional self-poisoning, and where do they obtain these substances?
Methods
The MOH Mortality data and National Minimum Dataset (NMDS) public hospital presentation cases of intentional and undetermined intent self-poisoning were analysed to investigate demographic characteristics of people who present with ISP, and to investigate limitations of the current data. Poisonings of undetermined intent were included as they may be poorly identified cases of ISP.
Specific poisoning data collected at one Emergency Department (ED; Wellington) were analysed to provide more information about specific substances used in ISP, and to investigate feasibility of clinicians recording these data.
The process of identifying poisoning and intentionality in patients presenting to an ED, which is then recorded in NMDS data, was investigated through interviews with clinicians and clinical coders.
Cross-sectional data were collected prospectively from three EDs. This included data on specific substances and sources to these substances.
Results
Females were at higher risk of hospital presentations for ISP, and males were at higher risk of death. Young people, Māori, New Zealand Europeans and people from deprived areas were most at risk. There are few details about specific substances in existing MOH data. The data recorded by clinicians in Wellington ED provided more detail about substances but coding was less systematic. A range of information along the care pathway is used to determine whether a poisoning has occurred and whether it is intentional. Intent can be complex to determine as it may change over time from the substance exposure to the time of treatment at the ED, particularly in cases of alcohol/recreational drug co-intoxication. We found that clinical coders do send data on specific substances to the MOH although these do not appear in the MOH datasets. The five most frequent substances used by people in the prospective study were paracetamol, ethanol, ibuprofen, quetiapine, and venlafaxine. Most people used their own prescription drugs.
Conclusions
Current national MOH datasets describing ISP are not detailed enough to identify specific substances of concern. The study shows that it is feasible to collect this data, but attention needs to be paid to standardisation. This data could inform measures to prevent ISP
