Purpose
To estimate the prevalence of psychiatric morbidity and dual diagnosis in a population of decedents with positive drug toxicology and evaluate changes over time between 2001–2002 and 2011–2012.

Materials and methods
A total of 520 autopsied drug users with positive toxicology were included in the study from 2001 to 2002 and from 2011 to 2012. Materials included autopsy reports, toxicological screening during autopsy and data from the Danish national health registers, including psychiatric diagnoses from psychiatric hospitals and ambulatory functions, dispensed prescription use from pharmacies and registered treatment for drug use disorders.

Results
In 2001–2002, 63.3% of the decedents had only positive toxicology, 22.5% also had psychiatric morbidity, and 14.2% had a dual diagnosis. In 2011–2012, 56.4% had only positive toxicology, 26.1% also had psychiatric morbidity, and 17.5% had a dual diagnosis. None of the changes were significant. Decedents with only positive toxicology became older at time of death over time; decedents with psychiatric morbidity and a dual diagnosis did not. The prevalence of nonprescribed psychotropic medication, methadone and benzodiazepines increased.

Conclusion
Decedents with psychiatric morbidity and dual diagnosis did not increase their lifespan over a 10-year period. Decedents with only positive toxicology increasingly consumed nonprescribed psychotropic medication and may have suffered from undiagnosed psychiatric disorders. The prevalence of prescribed and nonprescribed benzodiazepines and methadone increased and may have contributed to premature mortality.