Bipolar Disorder and Poisoning due to Medicines or Illegal Substances

Individuals with bipolar disorder face an elevated risk of premature death, often due to external causes such as accidental injuries, self-harm, and substance-related deaths. This study aimed to investigate the incidence of severe poisonings among individuals with bipolar disorder and to examine associated demographic and clinical factors.

We conducted a cohort study using data from national registers in Finland, measuring hospitalizations and deaths due to poisoning by medicines or illegal substances in 1996-2018. Cox proportional hazards regression models were used to assess associations between predictor variables and poisoning outcomes.

The study population comprised 60,045 individuals aged 15-65 diagnosed with bipolar disorder in 1987-2018. During the study period, 13.1% (N = 7872) of the population experienced at least one poisoning resulting in hospitalization or death. The age-standardized rate of hospitalizations was 50.6 (95% CI, 49.5-51.7) per 1000 person-years and of deaths 1.8 (95% CI, 1.6-2.0) per 1000 person-years. The majority of poisonings leading to hospitalization (59.1%) or death (56.6%) were intentional and caused by pharmaceuticals (hospitalizations, 76.9%; deaths, 63.6%). Additionally, psychoactive narcotics and stimulants were the cause of 26.8% of the poisoning deaths. The strongest risk factors for hospitalization were substance use disorder (adjusted hazard ratio, aHR, 2.75, 95% CI, 2.61-2.90) and a history of suicide attempt (2.70, 2.52-2.88). The risk of poisoning death was most strongly associated with substance use disorder (3.02, 2.60-3.52) and a history of suicide attempt (2.38, 1.94-2.91). Female sex was associated with a higher risk of hospitalization (1.19, 1.14-1.25), but a lower risk of death (0.72, 0.62-0.82).

Individuals with bipolar disorder face a substantial risk of poisoning by medicines or illegal substances, with notable sex differences in hospitalization and death rates. Key risk factors include substance use disorder and a history of suicide attempt.