Morbidity Consequences of Misuse of Psychoactive Prescription Drugs in Portugal: The MisuMedPT Project

Background: Hospital emergency admissions of patients suffering from psychoactive medicines' adverse effects provide important evidence on the risks associated to medicines acting on the central nervous system (CNS). This information can help to identify situations of misuse, making morbidity data useful as part of an active surveillance system for monitoring psychoactive medicines' misuse.

Objectives: To characterise admissions to emergency departments of Portuguese hospitals of patients presenting a diagnosis of abuse, poisoning or dependence of psychoactive medicines.

Methods: Retrospective observational study of visits to emergency departments (ED) of Portuguese hospitals of patients presenting at least one diagnosis of misuse of psychoactive medicines, coded as abuse, poisoning or dependence (2014-2018). The variables studied were demographic characteristics of individuals, therapeutic classes of medicines involved, hospitalisation length, episode severity, type of diagnoses and mortality risk.

Results: A total number of 13,815 admissions took place in Portuguese hospitals, increasing during the 5-year period (1,781 in 2014 to 3,934 in 2018), 7,593 females (55%) and 6,222 males, with a mean age of 47.4 years. In 88% of ED visits there was effective hospitalisation (mean length of stay: 11.3 days). Although more than half of the studied admissions were for other reasons, the diagnoses of interest not causing the ED visit (secondary diagnoses), about 48% of cases were due to psychoactive medicines' misuse, with a total of 9,357 cases with at least one poisoning diagnosis, 3,807 with dependence and 968 with an abuse diagnosis. There were statistical differences regarding the median duration of hospitalisation in admissions caused by misuse compared to the remaining studied admissions. A quarter of cases were of extreme and major severity (33% minor), with 18% of admissions presenting extreme and major mortality risks. Top therapeutic classes responsible for hospital admissions were anxiolytics (65%), followed by antidepressants (16%) both with a clear female predominance (73 and 75%, respectively), as opposed to prescription and illegal opioids (that caused only 3.4% of ED visits, 65% of which men). However, these admissions due to prescription and illegal opioids had a median duration of hospitalisation significantly higher (6 days) than the remaining users admitted due to misuse of other psychoactive therapeutic classes.

Conclusions: Our preliminary results show that anxiolytics, especially benzodiazepines, as well as antidepressants, are the main types of therapeutic groups responsible for hospital admissions involving psychoactive medicines, which show significant severity. Considering these classes are on the top of CNS-acting medicines' consumption in Portugal, our results call for further investigation. Work is currently undergoing to triangulate all morbi-mortality data collected from the different sources that compose the MisuMedPT Project, in order to have a holistic but detailed picture of psychoactive medicines' misuse and its consequences in Portugal.