Trends in overdose deaths from drug misuse inEurope: what do the data tell us?

During the 1990s the number of drug-related deaths(acute poisonings) in the United Kingdom increasedrapidly. Between 1993 and 2000 the number of deathsdoubled from 864 to 1662 [1,2], precipitating the recog-nition that reducing drug misuse deaths was a publichealth priority [3]. The UK Advisory Council on theMisuse of Drugs recommended the creation of a new sur-veillance indicator to follow overdose trends, which wasincorporated into the government’s drugs strategy. Atarget was set to reduce deaths related to drug misuse by20% by 2004 compared to a 1999 baseline [4]. As morethan three-quarters of drug-related poisonings in theUnited Kingdom are opiate-related, expanding drug treat-ment options, especially methadone maintenance forproblem opiate users, was seen as a critical overdose pre-vention measure [5]. UK and European indicators ofdrug-related deaths include deaths certified as due to druguse or misuse and include acute poisonings (overdosedeaths) based on routine mortality statistics; the indica-tors exclude other deaths that may have been causeddirectly or indirectly by drug use but which cannot beattributed readily to drug use within routine statistics(such as infections, other injuries or chronic diseases) [1].

Early signs were very encouraging. Between 2001 and2004, the government investment in specialist drugtreatment doubled to over £250 million annually [6]. Thevolume of methadone prescriptions increased markedly,and there was a drop in the estimated number of deathsper 1000 patient-years treated with methadone [7]. Thenumber of drug misuse deaths fell from 2001, and by2003 the reduction in drug-related deaths had almostreached the target. However, in 2004 and 2005 therewere sharp increases in drug misuse deaths, due largelyto heroin overdose, meaning the government’s target wasnot met [8,9].

The European context is presented in Fig. 1, whichcompares trends in overdose deaths in selected Europeancountries with similar population sizes [10]. The figureshows drug misuse deaths per million population from1993 to 2005 for England and Wales, Italy, Germany andSpain (Madrid, Barcelona, Valencia, Bilbao, Seville andZaragoza only) based on routine mortality statistics. Thedrug-poisoning mortality rate in these six Spanish citiesprobably overestimates the rate for Spain overall, but islikely to provide an accurate representation of trends overtime.

By 2004/05 the drug misuse mortality rates inEngland and Wales was one of the highest in Europe.However, case definition and data extraction from mor-

tality statistics varies between countries despite therebeing a common European definition [11], which mayexplain, in part, the difference in the size of the mortalityrates between countries. There have been no changes inthe compilation of statistics over time. More illuminating,therefore, and a salutary reminder to policy makers inEngland and Wales, is the difference in trends over time.In none of the other selected European countries did theoverdose mortality rate double during the 1990s. Insteadthe evidence suggests that mortality rates declined inSpain and Italy and were stable in Germany. In addition,the other selected countries all achieved substantiallygreater reductions in drug-related deaths than Englandand Wales between 1999 and 2004/05, with Germanyand Italy exceeding a 20% reduction and Spain (six cities)reducing the drug-related mortality rate by 17%.

Surveillance of deaths related to drug misuse is impor-tant for measuring the impact of interventions and forplanning future harm minimization strategies, but itcannot answer more fundamental questions. What arethe main drivers of drug overdose trends? Is the risk ofoverdose changing? Clearly, the number of overdosedeaths is related to the interplay between changes in thesize of the drug-using population and to their overdosemortality risk, with the latter related to other factors suchas the proportion of IDU in treatment or changes in drugadministration. The increase in overdose deaths duringthe 1990s in England and Wales was driven largely byincreases in the prevalence of heroin use [2,8]. We havehypothesized that the reduction in overdose deaths from2001 may have been the result of the rate of increase intreatment superseding any increase in the prevalence ofdrug misuse, and reducing the overall risk of overdosedeath [6,12].

However, in the United Kingdom since 1993 there hasbeen no investment in large-scale longitudinal studiesthat could test this hypothesis and monitor whether theoverall risk of overdose is declining, or the emergence ordecrease of other forms of mortality among drug users.There have been a few, mainly city-based, studies inEurope [13], but the mortality patterns can be changingsubstantially and quickly [14–17] and large-scale cohortstudies are needed in different European countries thatcan provide comparable information about overdose risk.Interpreting mortality statistics and trends in drug use iscomplex, and unlikely to lead to any firm conclusionswithout information on overdose risk. The figure showsthat trends in overdose deaths vary between countries,implying differences in either the numbers of heroin

EDITORIAL doi:10.1111/j.1360-0443.2007.02102.x

© 2008 The Authors. Journal compilation © 2008 Society for the Study of Addiction Addiction, 103, 699–700

injectors or overdose mortality risk. What we need toknow, however, is whether (and why) the other Europeancountries experienced a reduction in overdose mortalityrisk and/or prevalence of injecting drug use. We believe itis important now that we seek a better understandingof the mechanisms that underlie overdose mortalitystatistics.

Keywords Drug misuse, mortality, overdose, surveil-lance monitoring.

OLIVER MORGAN

Imperial College, UKE-mail: omorgan@bigfoot.com

JULIAN VICENTE & PAUL GRIFFITHS

European Monitoring Centre for Drugs and Drug Addiction,Portugal

MATTHEW HICKMAN

University of Bristol, UKReferences

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Figure 1 Drug misuse mortality rates permillion population aged 15–64 in selectedEuropean countries, 1993 to 2005. For allcountries rates are calculated using the Euro-stat populations except for Spain, where dataare shown for six cities (Madrid, Barcelona,Valencia, Bilbao, Seville and Zaragoza) andpopulation data for these cities was providedby the 2001 Census

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© 2008 The Authors. Journal compilation © 2008 Society for the Study of Addiction Addiction, 103, 699–700