This technical protocol outlines the definitions, methods and other considerations involved in the collection of data on acute drug-related presentations in sentinel hospitals by the Euro-DEN Plus network.

Table of contents: 

• Introduction
• Objectives
• Ethical considerations
• Project oversight and governance
• Methods
• Data management and analysis
• Data variables
• References
• Appendix – Screenshots of Euro-DEN Plus REDCap

Illicit drugs and new psychoactive substances (NPS) are commonly used across Europe. Acute toxicity from their use, along with acute toxicity from the non-medical use (misuse) of prescription medicines, can lead to emergency department (ED) presentations with the potential for significant morbidity and/or mortality. For the purpose of this protocol, the term ‘recreational drug’ encompasses these three substance groups. A previous study showed that there are limited systematic data available at a national or international level on acute harm related to the use of recreational drugs (Heyerdahl et al., 2014). It is not possible to easily collect these data from national/central sources because of the limitations in the coding of acute drug toxicity using coding systems such as ICD-10 (Wood et al., 2019). This lack of systematic data on acute drug toxicity represented a significant gap in the public health understanding of the implications of drug use in Europe.

To address this gap, the European Drug Emergencies Network (Euro-DEN) project was set up in 2013, originally funded for 12 months by the DPIP/ISEC Programme of the European Union. The project has continued as the Euro-DEN Plus project, with support from the EMCDDA/EUDA. The aim of the project is to increase knowledge on ED presentations with acute toxicity related to the use of recreational drugs across Europe, in order to contribute, along with other sources of information, to monitoring and act as an early warning system on drug-related harms, as well as to inform responses and policies in Europe.

A network of sentinel centres across Europe was developed to collect systematic data on acute drug and NPS toxicity presentations. Data are collected using a purpose-built representative minimum dataset (Wood et al., 2014). These data are collected from routine hospital medical records, with no additional information collected over and above that collected as part of routine clinical care. Data were initially collected in an Excel spreadsheet (from 2013-2022). In 2022, the project adopted the secure and EU-approved REDCap online database for data collection. The data are collated by the Euro-DEN Plus coordinating centre in London, UK. The EUDA provides support with data quality control for the Euro-DEN dataset.

The initial Euro-DEN project involved 16 centres in 10 European countries. Over the lifetime of the Euro-DEN Plus project, 53 centres in 27 countries have contributed data. In 2025, there were 37 active centres in 21 countries, and over 90 000 presentations were recorded in the database. The description of the centres is available in the Source table section of the Euro-DEN Plus data explorer (EUDA, 2025)....