Prescribed medication availability and deliberate self-poisoning: a longitudinal study

Abstract

Objective: The availability of prescribed medication to patients who engage in deliberate self-poisoning (DSP) is not known, and it is not clear whether patients choose drugs prescribed to them for self-poisoning. The objectives of this study were to investigate (1) prescribed medication availability in DSP patients compared to the general population, (2) whether patients use their prescribed medication in their DSP episodes, (3) differences between patients who ingest prescribed medication and those who do not, and (4) the time between the last collection of prescribed medication used for DSP and the DSP episodes.

Method: The design was longitudinal. We included 171 patients admitted for DSP to 3 hospitals in Eastern Norway between January 2006 and March 2007. Data on patients' prescriptions prior to admission were retrieved from the Norwegian Prescription Database (22.5 months of observation time). The primary outcome measure was type and amount of drugs ingested in the DSP episode.

Results: DSP patients had a much greater prescribed medication load compared to the general population, with a mean of 30 prescriptions collected in the year prior to DSP. In total, 77.2% of patients ingested drugs that they had collected, whereas 25% of patients used drugs collected the week prior to admission. The tendency to ingest collected drugs increased with age (OR = 1.1, 95% CI = 1.01 to 1.11, P = .01). Patients who collected sedatives were more likely to use these for self-poisoning than patients who collected antidepressants.

Conclusions: The much greater medication load of DSP patients is particularly important given their tendency to ingest their prescribed medication in self-poisoning episodes. The study indicates that timing of collection of medication prior to an episode is less important than general medication load. More attention should be directed to the total medication load for individuals at risk of self-harm.