The opioid epidemic: A worldwide exploratory study using the WHO pharmacovigilance database

The current opioid epidemic in the United States began 20 years ago and has become the leading cause of accidental deaths in the country. This crisis prompted us to explore trends in opioid abuse and dependence worldwide. We sought to identify other countries at high-risk of opioid use disorders, using the World Health Organization's (WHO) pharmacovigilance database.

We performed a disproportionality analysis using VigiBase, the WHO Global Individual Case Safety Report (ICSR) database. Five opioids used worldwide were included: oxycodone, fentanyl, morphine, tramadol, and codeine. We extracted all ICSRs associated with the drugs of interest, considered as suspect medication and recorded up until 5 June 2021, using the narrow Standardised MedDRA Query (SMQ) for drug abuse and dependence. Countries with at least one ICSR for each of the five opioids were retained. The relationship between the use of a drug (i.e. an opioid) and the occurrence of an adverse drug reaction (i.e. drug abuse and dependence) for each country was assessed by calculating the information component (IC) and its 99.9% CI [IC₀₀₀₅ ; IC₉₉₉₅ ], using a quasi-Bayesian confidence propagation neural network (BCPNN). A hierarchical cluster analysis (Ward's method) of the IC₀₀₀₅ value for each of the five opioids was performed to identify subgroups of countries with similar reported risks of opioid abuse and dependence.

Among 21 countries, the optimal number of clusters was calculated to be four, each with a Jaccard index >0.5 (0.95, 0.78, 0.65 and 0.75, respectively). Six countries with the highest signals of drug abuse and dependence were identified in cluster 1, with significant CIs for the five opioids of interest (IC₀₀₀₅  > 0), ranging from 0.9 to 5.8 for the lower endpoint.

There appear to be four distinct clusters of countries with similar opioid abuse and dependence profiles. The group with the highest reported risk for the opioids oxycodone, fentanyl, morphine, tramadol and codeine includes Australia, Canada, France, Germans, the United Kingdom and the United States.