Mortality consequences of misuse of psychoactive prescription drugs in Portugal - the MisuMedPT project

Background: Forensic data, together with poison centre and hospital information, are useful, as part of an active surveillance system for monitoring medicines misuse and drug abuse, to study risks associated to these behaviours. We aimed to investigate demographic characteristics, polydrug use and medicines’ role in Portuguese death cases.

Methods: Observational study of all medico-legally investigated deaths 2014-2018 involving psychoactive medicines, included in the database of the National Institute of Legal Medicine and Forensic Sciences (INMLCF). Using sales data from Health Market Research, medicine utilisation-based death rates and the relationship between the number of deaths and medicines’ exposure, were investigated.

Results: The rate of deaths involving at least one psychoactive medicine (N=7,653) among all violent or ignored cause deaths, has decreased from 2014 to 2016, but increased in 2017 and 2018, reaching 26.7% in 2018 (17.4 deaths/100,000 inhabitants), 71.1% of which unintentional. The number of benzodiazepines involved in fatal cases has decreased, from 1,361 in 2014 to 1,160 in 2018; strong prescription opioids show an opposite trend (64 to 151 positive toxicology reports). In 4.8% of studied deaths, autopsies confirmed the medicine’s contribution to the fatal outcome. In 20% of deaths, there was polydrug use, 14.2% with alcohol (75% males; 28% older than 65 years) and 4.2% with illegal drugs (N=323, 78% males), of which 48% with cocaine and 58% with cannabis.  In 2018, midazolam, diazepam, fentanyl and tramadol had the highest utilisation-based death rates (1,194, 1,028, 865 and 808 deaths/100,000 patients treated). A significant medium positive relationship between sales data and psychoactive medicine deaths was found (Pearson r = 0.412; p = 0.010).

Conclusion: Our results, pointing to an increase in deaths involving psychoactive medicines in which 20% also involve other CNS-acting substances, highlight the importance of using medicine-related morbi-mortality data as a tool to monitor medicines’ misuse and increase the safety of their use.