Mortality Among Users of Amphetamine-Type Stimulants
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Global Burden of Disease Mental Disorders and Illicit Drug Use Expert Group Jessica Singleton, Louisa Degenhardt, Wayne Hall and Tomas Zabransky Mortality among users of amphetamine type stimulants Illicit Drugs Discussion Paper No. 4 GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au MORTALITY AMONG USERS OF AMPHETAMINE TYPE STIMULANTS Jessica Singleton, Louisa Degenhardt, Wayne Hall and Tomas Zabransky Illicit Drugs Discussion Paper No. 4 Recommended citation: Singleton, J., Degenhardt, L., Hall, W., & Zabransky, T. (2008). Mortality among users of amphetamine-type stimulants. Global Burden of Disease Mental Disorders and Illicit Drug Use Expert Group, Illicit drugs discussion paper No. 4. National Drug and Alcohol Research Centre, University of NSW: Sydney. ISBN: 978 0 7334 2691 9 ©NATIONAL DRUG AND ALCOHOL RESEARCH CENTRE, UNIVERSITY OF NEW SOUTH WALES, SYDNEY, 2008 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. All other rights are reserved. Requests and enquiries concerning reproduction and rights should be addressed to the information manager, National Drug and Alcohol Research Centre, University of New South Wales, Sydney,NSW 2052, Australia. GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au Table of contents Overview and recommendations ....................................................................................... 1 1. Introduction ............................................................................................................... 2 2. Method ...................................................................................................................... 3 2.1. Identifying studies ......................................................................................... 3 2.2. Included studies ........................................................................................... 3 2.3. Excluded studies ........................................................................................... 4 2.4. Data extraction ............................................................................................. 4 2.5. Quality score ................................................................................................ 4 2.6. Calculation of comparable estimates ............................................................ 4 3. Results ....................................................................................................................... 6 3.1. All-cause mortality ....................................................................................... 7 3.2. Pooled estimates ......................................................................................... 13 4. Discussion and conclusions ..................................................................................... 14 4.1. Limitations .................................................................................................. 15 4.2. Conclusions ................................................................................................ 15 5. References ............................................................................................................... 17 Appendix A: Database information .................................................................................. 18 Appendix B: Search strings for literature searches ............................................................. 19 Appendix C: Number of articles identified from ATS mortality search combinations ........ 21 GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au List of tables Table 2. Cohort studies investigating mortality associated with ATS use ..................... 10 Table 3. Excluded studies investigating mortality associated with ATS use ................. 12 List of figures Figure 1. Flowchart of search strategy to identify articles reporting on mortality associated with amphetamine type stimulant use .......................................................................... 6 GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au Acknowledgements Dr Sharlene Kaye National Drug and Alcohol Research Centre, Sydney Professor Shane Darke National Drug and Alcohol Research Centre, Sydney GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au Overview and recommendations • This discussion paper outlines the results of a comprehensive search of the peer- reviewed literature to identify studies of mortality among people who use amphetamine type stimulants (ATS). • Three electronic databases were searched (EMBASE, Medline and PsychINFO) and “grey” literature was located using online libraries with contributions from trained librarians and experts in drug research. • The peer-reviewed search resulted in 2187 articles and an additional 9 grey literature sources. After thorough review, 72 articles were identified as reporting on the mortality of ATS users. Only 7 of these provided data from cohort studies that could be used to estimate mortality rates. • Overall, both the amount and quality of data on mortality was poor. The geographic spread of the information was also restricted to predominantly high income countries in Western Europe. The limited detail reported in the results was also problematic. Standardised mortality ratios were rarely reported and consequently crude mortality rates had to be used. • Attempts were made to calculate crude mortality rates for six of the cohort studies. A pooled crude mortality rate of 0.72/100 person years was derived. • Only one cohort of ATS users, in the Czech Republic, reported standardised mortality ratios (SMRs): they were 6.22 overall, 5.87 for males and 7.84 for females. • There are insufficient data from cohort studies of dependent users of ATS to evaluate the number of deaths due to specific causes (eg: suicide, overdose). Mortality due to individual causes cannot currently be estimated in a comparative risk assessment for ATS except as captured in separate estimates of injecting drug use (which may or may not be ATS injection). • The risk of non-fatal acute myocardial infarction may be analysed depending upon the results of a separate review. • Given widespread use of ATS globally[1], the known non-fatal adverse effects of use[2] and the elevated mortality rate reported here, cohort studies investigating the morbidity and mortality associated with such drug use should be a research priority. Results of such studies should be reported in a standard and consistent way, with significant improvements in reporting of mortality rates by including person years of follow up, standardised mortality ratios and specific causes of death. 1 GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au 1. Introduction The global prevalence of the use of amphetamine type stimulants (ATS) rapidly increased during the 1990s. In some countries, demand has continued to increase (eg: South Africa and Iraq), while in others there has been a recent decline in use (e.g. Spain, United States of America)[1]. ATS are currently the dominant substance of concern in the Pacific and in several countries in East Asia[3]. There is clearly an imperative to estimate the extent of mortality attributable to ATS use. This is the first comprehensive global review of the mortality associated with dependent ATS use. A variety of definitions of amphetamines and stimulants exist in the literature. “Amphetamines” can include: amphetamine, methamphetamine, 3,4- methylenedioxymethamphetamine (MDMA – commonly referred to as Ecstasy), methcathinone, and ephedrine. They may also include pharmaceutical forms such as phentermine. For the Global Burden of Disease project, use of “amphetamine type stimulants” refers to use of amphetamine and methamphetamine. Where the data are available, the misuse of pharmaceutical amphetamines (used largely to treat attention deficit disorder and as appetite suppressants) will also be included. The current paper is a review of the literature on mortality associated with the dependent use of amphetamine type stimulants. Limitations of the data mean that only all-cause mortality can be discussed. 2 GBD2005 Mental Disorders and Illicit Drug Use Expert Group www.gbd.unsw.edu.au 2. Method 2.1. Identifying studies A systematic literature review was conducted which identified peer reviewed articles and other sources of data describing ATS related mortality. After consultation with qualified librarians, tailored search strings were devised and used to search three electronic databases: EMBASE, Medline and PsycINFO (see Appendix A). This combination of databases provides the most complete coverage of catalogued literature. Search strings contained keywords and database-specific terms (MeSH headings, EMTREE terms and explode terms). Search strings were developed for four themes: amphetamine type stimulants, drug use, mortality epidemiology and cohort studies (see Appendix B). Multiple variations of the four search themes were combined to produce a set of results (see Appendix C). All results were limited to human subjects and publication years between 1990 and 2007. Any cohort studies published between 1980 and 1989 were also included. Grey literature reporting on ATS related mortality was identified using online grey literature databases, library databases and general online searches (the complete