The heroin epidemics that spread across Europe in the 1980s resulted in increasing numbers of overdose deaths (¹) among opioid users, which peaked for the first time around the turn of the millennium. A new record number for the countries reporting to the EMCDDA (28 EU Member States, Turkey and Norway) was registered in 2016, with 9 138 overdose deaths. At country level, the most recent data from a number of the countries with relatively robust reporting systems, including Ireland, Lithuania, Sweden and the United Kingdom, show an increase. The 2016 data show an increasing trend for the fourth consecutive year.

Drug overdose continues to be a major cause of death, especially among young people in Europe, with data showing that males are disproportionally affected. Overdose mortality rates are highest at age 35-39 for males, with 57.4 deaths per million, and at age 40-44 for females, with 12.4 deaths per million. Mean age at death, however, is 39 years old for both men and women. European countries have implemented a variety of approaches in their attempt to reduce overdose deaths at the national level, using evidence-based interventions drawing on an understanding of individual and environmental risk factors.

Which factors increase the risk of fatal and non-fatal overdose?

The type of substance used, the route of administration and the health of the user all have an impact on the risk of overdose. Most overdose deaths are linked to the use of opioids, primarily the injection of heroin. Heightened levels of risk are also associated with the misuse of certain prescription drugs (e.g. benzodiazepines), and the non-medical use of prescribed substitution medications and opioid analgesics (EMCDDA, 2017, 2018a; Giraudon et al., 2013). In addition, a substantial number of deaths involve polydrug use, particularly heroin in combination with other central nervous system depressants, such as alcohol or benzodiazepines.

Highly potent new synthetic opioids seem to play an increasing role in drug overdose in Europe. Of particular concern are the fentanyl derivatives, which make up the majority of the new opioids monitored by the EMCDDA. Because of the high potency of these substances, minute quantities can cause life-threatening conditions, due to rapid and severe respiratory depression. This makes them especially dangerous, particularly for unsuspecting users who believe they are using heroin, other illicit drugs or pain medicines. The dangers to public health posed by these substances are being witnessed in the United States, where synthetic opioids other than methadone, mostly illicitly manufactured fentanyls (Centers for Disease Control and Prevention, 2018) are now one of the main drivers behind a continuing surge in overdose deaths. A rapid increase in deaths attributed to this group of substances has been noted over recent years, with 19 413 deaths in 2016, corresponding to 6.2 deaths per 100 000 population, a six-fold increase from 1.0 deaths per 100 000 population in 2013.

A number of environmental factors increase the risk of drug overdose death including, in the case of opioid users, disruption of treatment provision or discontinuity of treatment and care. In certain situations, for example following detoxification or discharge from drug-free treatment, the tolerance of drug users to opioids is greatly reduced and, as a result, they are at particularly high risk of overdosing if they resume use. For these same reasons, inadequate throughcare between prison and community has also been identified as an important environmental risk factor (WHO, 2014; Zlodre and Fazel, 2012). In a cohort study in England, differences in the risk of fatal opioid poisoning were identified, dependent on the type of treatment received: opioid users who received only psychological support appeared to be at greater risk than those who received opioid agonist pharmacotherapy (Pierce et al., 2016).

Finally, the lack of response or inadequate interventions by those witnessing overdoses, whether due to poor first aid knowledge, lack of access to effective medication or fear of legal repercussions, increases the risk of an overdose event having a fatal outcome (Frisher et al., 2012). A study in Bergen, Norway analysed differences in the time emergency services needed to arrive after overdose call-outs to private or public addresses. Ambulance response times were more likely to be longer for private locations; victims at private homes were more likely to be left at the scene after being treated and less likely to be transported to hospitals (Madah-Amiri et al., 2016).

A range of responses: reducing the number of overdoses and preventing deaths

Drawing on the insights gained from risk and protective factors, the prevention of overdose deaths is generally addressed at three levels (see Figure 1). As a basis for a successful response, broader public health approaches such as provision of outreach and low-threshold services and enabling environments can reduce access barriers and thus reduce vulnerability to overdose, while empowering drug users to protect themselves may provide an environment in which overdoses are less likely. The second level involves a set of interventions geared towards preventing the occurrence of overdoses, while the third level focuses on reducing morbidity and fatal outcomes when an overdose has happened (EMCDDA, 2017).

Below, we introduce some of the most important strategies used by countries to address overdose prevention.

Increasing awareness of and information about overdose risks

A history of opioid use is a risk factor for overdose, and those who report prior overdoses are at a higher risk of overdosing again. As many drug users either are unaware of or seriously underestimate overdose risks, effective communication with users can act as a catalyst for reducing harm. Ideally, overdose prevention, education and counselling interventions would be provided by trained professionals as a matter of routine in the relevant health and primary care settings. Screening for overdose risk by those treating heroin users may contribute to reductions in overall mortality (Darke et al., 2011), while the use of overdose risk assessment interventions can assist the early identification of high-risk individuals. All EU Member States and Norway report the distribution of overdose risk information, which is sometimes also available in different languages in order to be accessible to migrant drug users. An e-health overdose risk assessment tool and overdose awareness videos, which may be projected in the waiting rooms of drugs facilities (e.g. http://vimeo.com/album/1655129), have also been produced.

Acknowledging the risk of mortality related to prescription opioids witnessed in the United States, EU countries now have an opportunity to adapt and scale up their prevention measures, reinforce surveillance and introduce improved regulatory measures to prevent deaths reaching epidemic proportions (Giraudon et al., 2013).

Provision of effective drug treatment and retention in treatment

There is convincing evidence that opioid substitution treatment (OST) substantially reduces the risk of mortality, as long as doses are sufficient and continuity of treatment is maintained (EMCDDA Best practice portal; Pierce, 2016). A prospective observational cohort study conducted in Edinburgh confirmed that survival is increased by cumulative exposure to treatment (Kimber et al., 2010). As retention in drug treatment is a protective factor against overdose deaths, many European countries have given priority to increasing access to and coverage of treatment services.

With OST provision high, medical staff and service planners face the challenge of minimising the diversion of substitution medications to those without prescriptions while continuing to ensure that access to treatment is not impeded, for example by supervising consumption. Another widely used approach to reducing the risk of overdose is the implementation of good treatment practice, which involves the use of clinical guidelines and training doctors in prescribing practices (including benzodiazepine prescribing).

Improving throughcare between prison and community

Several interventions are recommended to help reduce the high number of overdose deaths among former prisoners in the period shortly after leaving prison (Binswanger et al., 2013; Merrall et al., 2010). These include pre-release education on overdose risks and prevention, continuation and initiation of substitution treatment (Degenhardt et al., 2014), naloxone distribution (Meade et al., 2018) and improved referral to aftercare and community treatment services (WHO Regional Office for Europe, 2014). A current EU-funded multi-country project ‘My first 48 hours out’ (Belgium, Germany, France, Portugal) explores approaches to pre-and post-prison release interventions to reduce harms, through investigating risk behaviour of people upon release from prison and documenting best practices.

Prevention of deaths in overdose situations

A second set of responses focuses on the prevention of fatalities when overdoses occur. These include a range of targeted interventions, the purpose of which is to enhance safety and ensure a rapid and effective response in emergency situations.

Supervised drug consumption rooms

A total of 78 facilities for supervised drug consumption operate across six EU Member States (Denmark, Spain, Germany, France, Luxembourg, Netherlands) and Norway, serving specific subgroups of highly marginalised and homeless drug users. Supervised drug consumption facilities aim to reach marginalised high-risk drug users and connect them to the wider network of care, to reduce the acute risks of diseases and overdose death associated with injecting or inhalative drug use, and to reduce public drug use (Belackova and Salmon, 2017). Consumption rooms are highly targeted services, usually integrated within facilities that offer a broad range of other health and social services. They provide a safer drug use environment, advice on safer injecting and medical supervision, and are equipped to manage drug overdoses and reduce related morbidity and mortality. Millions of injections have been supervised and no overdose fatalities have occurred in the facilities. Evidence from robust studies documents increased access to health and social services among clients of supervised drug consumption facilities, and decreased public drug use and associated nuisance. A reduction in overdose mortality at the population level was documented in the city of Vancouver, in the local area where a supervised injecting facility operates (Marshall et al., 2011). See also, Drug consumption rooms (EMCDDA, 2018b).

Improved bystander response

Most overdoses occur when others are present, and most injecting drug users have witnessed or experienced overdoses. Therefore, drug users themselves, or their friends and family, are likely to be both bystanders and potential first responders in emergency overdose situations (Strang et al., 2008). These human networks, with appropriate training and awareness raising, can be utilised to prevent overdose deaths. Interventions that aim to improve bystander responses consist of training peers and family members of drug users in overdose prevention, recognition and response. A contextual analysis of ambulance call-outs to emergencies at private addresses (Madah-Amiri et al., 2016; see section on risk factors above) also indicates potential opportunities for peer overdose prevention interventions. In its guidelines on community management of opioid overdose, the World Health Organization (WHO) recommends that people likely to witness an opioid overdose should have access to naloxone — an effective antidote that can reverse opioid intoxication — and should be instructed in its administration (WHO, 2014). Evidence shows that educational and training interventions for peers and family members, complemented by take-home naloxone, help decrease overdose-related mortality. With evidence on its effectiveness growing, take-home naloxone provision has gained more attention in Europe in recent years. A recent EMCDDA publication brings together evidence as well as experiences from take-home naloxone projects in Europe and elsewhere (EMCDDA, 2016).

Conclusions

Drug overdose deaths are preventable, and there is good evidence to show that specific interventions can both reduce the occurrence of overdose events and prevent fatal outcomes in overdose situations. The accumulated knowledge about risk and protective factors associated with overdoses, and about the successful management of overdose situations, has grown. Access to OST, which constitutes an important protective factor, has been substantially scaled up across Europe. In addition, some countries have introduced new and targeted approaches, searching for innovative ways to identify those at risk of overdose, to raise risk awareness and to enable those who witness overdoses to intervene and prevent fatal outcomes.