What lessons from Sweden's experience could be applied in the United States in response to the addiction and overdose crisis?

Sweden's experience of opioid agonist treatment (OAT) can inform US decision‐making. After 2006, an increase in methadone‐related deaths has been observed outside treatment parallel with new OAT regulations with less restrictions. Considering this, a balance between access to treatment and safe administration of methadone with low risk for diversion is recommended.

Sweden has the highest mortality rate in the European Union (EU), according to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) [1]. Data from the Organization for Economic Co‐operation and Development (OECD) indicate that opioid‐related deaths increased both in Sweden and the United States during the period 2011–16, but decreased or stabilized in most other OECD countries [2].

The increase in drug‐related deaths in Sweden started in 2006, but in contrast to the United States the increase was mainly due to poisonings with methadone and buprenorphine, which are primarily used for OAT in Sweden.

Although OAT with methadone was introduced in Sweden in 1966 it was, and to some extent still is, controversial and therefore associated with many restrictions. For the small number in treatment, early studies showed reduced mortality, for instance in HIV‐infected patients [3]. Another study of the methadone programme in Stockholm, the largest in Sweden, from 1988 to 2000 showed reduced mortality and no methadone intoxications among patients in treatment and only a small number of methadone intoxications in the population in Stockholm, indicating low diversion from the programme [4].

In 2006 new regulations for OAT were introduced in Sweden and many restrictions were removed. In parallel to the expansion of the treatment there was an increase in the number of methadone‐related deaths in the population. A study of all 269 methadone‐related deaths in Sweden during 2006–15 in individuals aged 15–29 years revealed that only 10 individuals had been prescribed methadone during the year before death, indicating that most deaths occurred in people not currently receiving OAT [5]. Most deaths occurred during sleep with a time lag from ingestion of methadone, which indicates that they were unexpected. A high and increasing proportion of methadone poisonings in Sweden after 2006 has also been shown in another study [6].

In the United States, before the opioid overdose epidemic during the last decade, methadone was implicated in one‐third of opioid‐related overdose deaths, although the drug represented fewer than 5% of the opioid prescriptions dispensed at that time [7]. There are now suggestions to make the relaxations in methadone treatment implemented in the United States as a response to the COVID‐19 pandemic permanent, and allow reductions in in‐person dosing and attendance requirements based on short‐term mortality data [8]. Considering the experiences of increased methadone‐related mortality described above over longer time‐periods in Sweden, and also other countries in Europe with supervised versus non‐supervised methadone treatment [9], caution and collection of more long‐term data from the United States before making these policy changes permanent can be advocated.

Drug‐related deaths not caused by methadone during the last decade differ between Sweden and the United States. There has been a small increase in oxycodone‐related deaths in Sweden but to a much lesser degree than in the United States, and the number of heroin‐related deaths has been relatively stable since 2006 without any increasing trends.

The development of fentanyl‐related deaths is also different in Sweden compared to that in the United States. From 2015 to 2017 there was a marked increase in fentanyl‐related deaths, most probably due to the introduction of illicit fentanyl analogues sold over the internet, and during these 2 years fentanyl was the major opioid in poisoning deaths in Sweden. A court case ruling of aggravated involuntary manslaughter against one of the sellers in May 2018 caused the supply of illicit fentanyl to cease practically overnight [10]. This nation‐wide effect of a single court case would not be observed in the United States due to the size of the market for illicit fentanyl in that country.

A general lesson from Sweden's experience of drug‐related deaths is the importance of a register based on forensic examinations. Statistics based on forensic toxicology are more complete, provide more detail on used substances and are usually available earlier than national mortality register‐based statistics. The epidemiological studies of drug‐related mortality mentioned above are based on a central forensic database, and through the personal identification number the cases can be linked to registries of the official causes of death based on certificates, pharmaceutical prescriptions as well as previous hospital or outpatient treatment episodes. This enables studies of trends and causes of both general drug‐related deaths but also, as described above, alerts related to deaths caused by particular substances such as methadone or fentanyl.

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