Detailed analyses of self-poisoning episodes presenting to a large regional teaching hospital in the UK

Abstract

Aims: The primary aim of this paper is to provide comprehensive contemporaneous data on the demographics, patterns of presentation and management of all episodes of deliberate self-poisoning presenting to a large regional teaching hospital over a 12 month period.

Methods: We undertook detailed, retrospective analyses using information from electronic patient records and local patient-tracking, pathology and administrative databases. Statistical analyses were performed using Chi-squared tests, anova and two-tailed t-tests (Graphpad Prism).

Results: One thousand five hundred and ninety-eight episodes of deliberate self-poisoning presented over the year. Demographic data and information on the month, day and time of admission are provided. 70.7% presented to the emergency department (ED) within 4 h of ingestion. 76.3% of patients had only one episode in an extended 29 month follow-up period. A mean of 1.72 drugs were taken per episode with just over half of all episodes involving a single drug only. Paracetamol and ibuprofen were the two most commonly ingested drugs involved in 42.5% and 17.3% of all overdoses respectively. 56.3% of patients taking paracetamol reported ingesting over 8 g (one over the counter packet). Detailed mapping of the patients' pathway through the hospital allowed an estimation of the hospital cost of caring for this patient group at pound 1.6 million pounds per year.

Conclusions: We present comprehensive and contemporary data on presentations to hospital resulting from deliberate self-poisoning. We include demographic information, presentation patterns, drugs used, a detailed analysis of episodes involving paracetamol and an estimate of the financial burden to hospitals of overdose presentations.

Figure 1

Flow diagram to illustrate how data were collected for the study. ‘Duplicates’ were episodes that had been coded both in the emergency department (ED) and the acute medical unit (AMU) on the patient tracking system. Accidental overdoses and those miscoded as overdose were filtered out by a review of the medical records. A detailed breakdown of the admissions is included. (‘MSSU’ is the medical short stay unit: this is a general medical ward intended to care for patients with an anticipated length of stay of less than 48 h.)

Figure 2

The age distribution by gender for all episodes of self-poisoning. Female (); Male ()

Figure 3

The timing of all overdose presentations during the year of the study (bars plotted against the left-hand y axis) compared with all ED presentations in the year (line plotted against the right-hand y axis) over the 24 h period. OD episodes (); All ED episodes ()

Figure 4

The distribution of time from reported ingestion to presentation by plotting the number of patients presenting in each hour block

Figure 5

The distribution of the number of drugs taken in overdose. A total of 2703 drugs were taken by 1571 patients; data were not available in 27 episodes of self-poisoning

Figure 6

The amount of paracetamol ingested by patients who took paracetamol either alone or in combinations available over the counter. Data were available for 702/795 patients. Admitted patients (); Discharged from Ed ()

Figure 7

Plots of serum paracetamol concentrations against timing of the test superimposed onto the standard and high risk treatment nomograms as found in the British National Formulary. 7a represents patients discharged from the Emergency Department, and 7b those requiring medical admission. Where information on amount ingested was reported, this has been incorporated by the use of different point markers for those who ingested <8 g, 8–16 g and over 16 g paracetamol. Episodes where the ingested amount was not reported by the patient have been marked with a cross. Those patients for whom the timing of the overdose was unclear have not been included. Reported ingestion up to 8 g Paracetamol (○); Reported ingestion 8–16 g Paracetamol (□); Reported ingestion >16 g Paracetamol (▵); Unknown quantity of paracetamol taken (×)