Factors associated with history of non-fatal overdose among opioid users in the Swedish criminal justice system.

Background: Overdose (OD) is a common cause of death in opioid users. Also, many current opioid users report a history of non-fatal OD. The present study aimed to identify factors associated with a history of non-fatal OD.

Methods: A sample of 7085 Swedish criminal justice clients with alcohol or drug misuse was assessed, using the Addiction Severity Index. Subjects reporting use of opioids during the 30 days prior to incarceration were included (n=1113). Relevant variables of misuse pattern, heredity, psychiatric symptoms and previous criminal charges were analysed in a logistic regression model.

Results: A history of non-fatal OD was reported by 55% (n=604). The estimated contribution to the variance in OD history was 25% for variables describing misuse pattern, compared to 10% for psychiatric symptoms, 8% for heredity, and 8% for previous criminal charges. The final model included the following variables: history of injection drug use (OR 3.28), history of heroin use (OR 2.87), history of suicide attempt (OR 1.92), history of tranquilliser use (OR 1.91), being born in Sweden or other Nordic countries (OR 1.74), difficulty in controlling violent behaviour (OR 1.68), and paternal alcohol problems (OR 1.57).

Conclusions: Suicide attempts and difficulty in controlling violent behaviour were associated with history of non-fatal OD, independent of variables of misuse pattern. This may indicate a possible association with impulse control disturbances, and may have clinical applications. Country of birth and heredity of alcohol problems also had some influence. As expected, severity of misuse most strongly contributed to history of non-fatal OD.