A retrospective descriptive study of the characteristics of deliberate self-poisoning patients with single or repeat presentations to an Australian emergency medicine network in a one year period.

Background: A proportion of deliberate self-poisoning (DSP) patients present repeatedly to the emergency department (ED). Understanding the characteristics of frequent DSP patients and their presentation is a first step to implementing interventions that are designed to prevent repeated self-poisoning.

Methods: All DSP presentations to three networked Australian ED's were retrospectively identified from the ED electronic medical record and hospital scanned medical records for 2011. Demographics, types of drugs ingested, emergency department length of stay and disposition for the repeat DSP presenters were extracted and compared to those who presented once with DSP in a one year period. Logistic regression was used to analyse repeat versus single DSP data.

Results: The study determined 755 single presenters and 93 repeat DSP presenters. The repeat presenters contributed to 321 DSP presentations. They were more likely to be unemployed (61.0% versus 39.9%, p = 0.008) and have a psychiatric illness compared to single presenters (36.6% versus 15.5%, p < 0.001). Repeat presenters were less likely to receive a toxicology consultation (11.5% versus 27.3%, p < 0.001) and were more likely to abscond from the ED (7.5% versus 3.4%, p = 0.004). Repeat presenters were more likely to ingest paracetamol and antipsychotics than single presenters. The defined daily dose for the most common antipsychotic ingested, quetiapine, was less in the repeat presenter group (median 1.9 [IQR: 1.3-3.5]) compared with the single presenter group (4 [1.4-9.5]), (OR 0.85, 95% CI 0.74-0.99).

Conclusion: Patients who present repeatedly to the ED with DSP have pre-existing disadvantages, with increased likelihood of being unemployed and having a mental illness. These patients are also more likely to have health service inequities given the greater likelihood to abscond from the ED and lower likelihood of receiving toxicology consultation for their DSP. Early recognition of repeat DSP patients in the ED may facilitate the development of individualised care plans with the aim to reduce repeat episodes of self-poisoning and subsequent risk of successful suicide.