Bipolar disorder and severe poisoning due to medicines or illicit substances

Introduction:
Poisoning is suspected to cause excess mortality among individuals with bipolar disorder (BPD), but detailed studies on the subject are rare. We aimed to investigate hospitalizations and deaths by poisonings due to pharmaceuticals and illicit drugs among individuals with bipolar disorder (BPD).
Methods:
Utilizing national health registries, we included data on all individuals aged 15-65 diagnosed with BPD (ICD-10: F30–F31) between the years 1987 and 2018 in Finland to this study. For these individuals, we extracted data on hospitalizations and fatalities due to poisoning from the nationwide hospital discharge and cause of death register. These data were linked to other national registries with data on comorbidities and socioeconomic variables.
Results:
The study cohort included 60,045 individuals (56.4% female; mean age 41.7 years, SD=15.8) with BPD. During a mean follow-up of 9.3 years, 13.8% (n=8272) of the cohort experienced poisoning at least once. There were 0.84 fatal and 14.0 non-fatal poisonings per 1000 person-years. Most hospitalizations (59.7%) and deaths (56.4%) were deemed intentional. Previous poisonings (adjusted odds ratio 3.60, 3.39-3.83), younger age (15-24 vs. ≥55 years: 2.92, 2.65-3.22), substance use disorders (2.47, 2.33-2.62), and borderline personality disorder (1.29, 1.21-1.38) had the strongest association with any poisoning. 
Conclusion:
Especially intentional poisonings by medicines or illicit substances are frequent among individuals with BPD. Clinical treatment, including suicide prevention plans, should therefore be adjusted considering the patient’s risk for poisoning.