Morbi-mortality consequences of misuse of psychoactive prescription drugs in Portugal: a retrospective observational study - the MisuMedPT project

Background: Prescription drug misuse is a public health problem in some countries worldwide. In Portugal, there are no published data on the health-related consequences of medicine misuse, which is therefore a public health issue of unknown dimension in our country. Poison control centres, together with other pharmacoepidemiological sources providing information on prescription drug-related morbidity and mortality, can be part of an active surveillance system for monitoring drug abuse and medicine misuse.

Methods: Retrospective observational study of intentional exposures to medicines reported to the Portuguese Poison Information Centre (CIAV) from 1 January 2014 to 31 December 2017. Sixty-nine active substances from the ATC classes opioid analgesics, antiepileptics, anxiolytics, hypnotics and sedatives, antidepressants, psychostimulants and drugs used in opioid dependence, were included in the study. Main outcome measures are demographic characteristics of individuals, geographic distribution of calls, temporal evolution of exposures, co-exposure to alcohol or illicit drugs, route of exposure, call origin, case evaluation and guidance. Annual incidence rates of intentional exposures were also calculated, using census data as denominator.

Results: During the 4-year study period, 26636 calls were received at CIAV reporting 27622 intentional exposures to any medicinal product, with 25100 (90,9%) involving one of the psychoactive medicines included in the study. The districts of Coimbra, Oporto and Lisbon had the highest incidence rates of intentional exposures to the medicines of interest (182.4, 99.7 and 97.7 exposures per 100,000 inhabitants, respectively). Of these 25100 exposures, 19242 (76.7%) were considered symptomatic poisoning, 22.8% of which with emergency room visit advice or effective hospitalisation. The most frequently involved psychoactive medicines were benzodiazepines (55.3%), namely alprazolam (n=3970, 15.8%) and diazepam (n=3048, 12.1%), with the antidepressant trazodone ranking fifth (n=1458). Intentional exposure to the studied medicines was combined with non-medicinal products in 3934 exposures (15.7%), 1605 (40.8%) of which with alcohol. A total of 29 594 exposures to any of the studied medicines, illegal drugs or alcohol, were reported to CIAV during the study period. These exposures have occurred mainly in females (71.3%) and in 44.9%, individuals were aged between 35 and 54 years (median 40.0, mean 39.9 years). Poisonings to the psychoactive medicines studied remained stable during the 4-year period (6251 exposures in 2017).

Conclusions: In line with available literature, there is female predominance in the number of poisonings reported involving any of the psychoactive medicines studied. Benzodiazepines and antidepressants are on the top of the therapeutic classes reported. The incidence rate of intentional exposures to psychoactive medicines is markedly higher in Coimbra district, where the university student population rate is highest, requiring further analysis of the data. In order to adjust for the wide variability in the level of medicines’ use in the population, work is undergoing to include rates of intentional poisonings in patients prescribed any of the studied medicines. With the aim of better characterising the potential consequences of misuse of psychoactive prescription drugs in Portugal, additional forensic data of deaths involving these medicines will also be included in the MisuMedPT project.