Repeated poisonings in Denmark - a nationwide study

Poisonings contribute significantly to morbidity and mortality of patients. Some patients have numerous contacts to a poison information center, indicating repeated poisoning exposures. Information on the involved substances is necessary to explore methods to prevent self-harm and reduce mortality. The objective of this study was to characterize the patient population with repeated poison exposures in Denmark and identify the substances involved.

This study was a retrospective cohort study of enquiries to the nationwide Danish Poison Information Centre and the Danish National Patient Registry. The databases were used to identify patients with more than five individual poisoning episodes within a 12-month-period between 1 January 2013, and 31 December 2017.

One hundred and thirty-seven patients and 995 patients met the inclusion criteria in the Danish Poison Information Centre and the Danish National Patient Registry, respectively. The majority were women (82.5% and 66.3% for the Danish Poison Information Centre and the Danish National Patient Registry cohorts, respectively). The mean age was 24.7 and 29.5 years. Psychiatric comorbidities were frequent with 74.5% and 67.0% suffering from personality disorders and 70.1% and 54.5% from affective disorders in the Danish Poison Information Centre and the Danish National Patient Registry cohorts, respectively. One thousand seven hundred and fifty-two poisoning episodes were identified in the Danish Poison Information Centre database, and the most common types of substance were 'pharmaceuticals' (1,420 episodes). The most common medications ingested were quetiapine, paracetamol and cyclizine. Median number of contacts to the Danish Poison Information Centre was 10. Patients with one or more poisoning episodes involving cyclizine had on average 11.4 poisoning episodes involving cyclizine. In the Danish National Patient Registry cohort 80.9% were alive after 10 years compared to 97.7% in the background population.

Most poisonings were intentional and occurred among younger women. Psychiatric comorbidity was frequent. Most often, pharmaceuticals were the toxic substance, mainly quetiapine, paracetamol and cyclizine. Changing the status of cyclizine from over the counter to prescription only medication, and implementing stricter rules for prescribing quetiapine, could limit future poisoning incidences.