Patterns of medicine use in the year prior to death by suicide: an Australian population-based case series study.

Background: Prescribed medicines are commonly used to treat mental health conditions but are also often implicated in suicide death by poisoning. This was a descriptive study quantifying changes in dispensing and initiation of antidepressants, benzodiazepines, and antipsychotics in the year prior to death by suicide. Methods: In this Australian population-based case series, we used national coronial data linked with dispensing claims for all people ≥10 years who died by suicide (2013-2019). Our primary outcome was change in aggregate weekly medicine dispensing the year before death, quantified using piecewise linear regression stratified by cause of death (medicine poisoning vs other causes). Our secondary outcome was change in medicine initiation rates. This study was performed between June 2021 and July 2023. Findings: Our study included 14,207 people (24% female, median age 44  years). In the year prior to death, we observed higher rates of nervous system medicine use in people who died by medicine poisoning compared with those that did not: antidepressants (62.4% vs 42.9%), benzodiazepines (51.4% vs 29.0%), antipsychotics (25.6% vs 17.1%), opioids (43.8% vs 23.4%). For benzodiazepines, among people who died by medicine poisoning the slope (rate of increase) changed from 0.18 (95% CI -0.01, 0.37) to 4.12 (95% CI 0.98, 7.26) dispensings per 1000 people per week at 8 weeks prior to death. Among people who died of other causes, the slope changed from 0.18 (95% CI 0.14, 0.22) to 2.41 (95% CI 1.90, 2.91) also at 8 weeks prior to death. For antidepressants, among people who died of medicine poisoning we observed no change in the slope. Among people who died of other causes, the slope increased from 0.18 (95% CI 0.09, 0.28) to 1.68 (95% CI 1.20, 2.15) at 14 weeks prior to death. Interpretation: Dispensing of antidepressants and benzodiazepines increased more rapidly closer to date of death, regardless of medicine involvement in death. This suggests these changes may reflect worsening symptoms or increased help seeking and that the method of death by suicide may be due to greater means access. However, findings need to be interpreted with caution as our analyses were performed on aggregate data and may not reflect person-level changes. Funding: This study is funded by a grant from the Australian National Health and Medical Research Council (NHMRC) and the Translational Australian Clinical Toxicology Research (TACT) Group.