摘要：Background. Drug overdose is an important, yet an inadequately understood, public health problem. Global attention to unintentional drug overdose has been limited by comparison with the scope of the problem. There has been a substantial increase in drug overdose incidence and prevalence in several countries worldwide over the past decade, contributing to both increased costs and mortality. Objectives. The aim of this study was to systematically synthesize the peer-reviewed literature to document the global epidemiological profile of unintentional drug overdoses and the prevalence, time trends, mortality rates, and correlates of drug overdoses. We searched different combinations of Medical Subject Headings (MeSH) terms in PubMed for articles published from 1980 until July 2013, and we organized these results in tabular spreadsheets and compared them. We restricted the search to English-language articles that deal with unintentional overdose, focusing on 1 or more of the following key constructs: prevalence, time trends, mortality rates, and correlates. The term “overdose” as a MeSH major topic yielded 1076 publications. In addition, we searched the following combinations of nonmajor MeSH terms: “street drugs” and “overdose” yielded 180, “death” and “overdose” yielded 114, and “poisoning” and “drug users” yielded 17. There was some overlap among the searches. Based on the search and inclusion and exclusion criteria, we selected a total of 169 relevant articles for this article based on a close review of abstracts. Results. We found wide variability in lifetime prevalence of experiencing a nonfatal overdose or witnessing an overdose, and in mortality rates attributable to overdose. Lifetime prevalence of witnessed overdose among drug users (n = 17 samples) ranged from 50% to 96%, with a mean of 73.3%, a median of 70%, and a standard deviation of 14.1%. Lifetime prevalence of drug users personally experiencing a nonfatal overdose (n = 27 samples), ranged from 16.6% to 68.0% with a mean of 45.4%, a median of 47%, and a standard deviation of 14.4%. Population-based crude overdose mortality rates (n = 28 samples) ranged from 0.04 to 46.6 per 100 000 person-years. This range is likely attributable to the diversity in regions, time periods, and samples. Most studies on longitudinal trends of overdose death rates or overdose-related hospitalization rates showed increases in overdose death rates and in overdose-related hospitalization rates across time, which have led to peaks in these rates at the present time. An overall trend of increasing deaths from prescription opioid use and decreasing deaths from illicit drug use in the past several years has been noted across most of the literature. With the increase in prescription opioid overdose deaths, drug overdose is not just an urban problem: rural areas have seen an important increase in overdose deaths. Lastly, cocaine, prescription opioids, and heroin are the drugs most commonly associated with unintentional drug overdoses worldwide and the demographic and psychiatric correlates associated with unintentional drug overdoses are similar globally. Conclusions. There is a need to invest in research to understand the distinct determinants of prescription drug overdose worldwide. Several other countries need to collect in a systematic and continuous fashion such data on sales of prescription opioids and other prescription drugs, nonmedical use of prescription drugs, and hospitalization secondary to overdoses on prescription drugs. The sparse evidence on the environmental determinants of overdose suggests a need for research that will inform the types of environmental interventions we can use to prevent drug overdose. Methodological issues for future studies include enhancing data collection methods on unintentional fatal and nonfatal overdoses, and collecting more detailed information on drug use history, source of drug use (for prescription drugs), and demographic and psychiatric history characteristics of the individual who overdosed. PLAIN-LANGUAGE Summary: Drug overdose is an important, yet inadequately understood, public health problem. The aim of this study was to systematically summarize the peer-reviewed literature to document the global epidemiological profile of unintentional drug overdoses, and the prevalence, time trends, mortality rates, and correlates of drug overdoses from 1980 until 2013. We found wide variability in prevalence mortality rates attributable to overdose. Most studies on longitudinal trends of overdose deaths or overdose-related hospitalizations showed increases across time. An overall trend of increasing deaths from prescription opioid use and decreasing deaths from illicit drug use in the past several years has been noted across most of the literature. With the increase in prescription opioid overdose deaths, drug overdose is not just an urban problem: rural areas have seen an important increase in overdose deaths. Lastly, cocaine, prescription opioids, and heroin are the drugs most commonly associated with unintentional drug overdoses worldwide and the demographic and psychiatric correlates associated with unintentional drug overdoses are similar globally. Future studies need to collect more detailed information on drug use history, source of drug use (for prescription drugs), and demographic and psychiatric history characteristics of the individual who overdosed. Worldwide attention to unintentional drug overdose has been limited by comparison with the scope of the problem. 1 There has been a substantial increase in drug overdose mortality in several countries worldwide over the past decade. The mortality rate from drug overdoses tripled in the United States between 1990 and 2006. 2 In the United States, unintentional overdose deaths among adults aged 25 to 64 years exceeded motor vehicle crash deaths and suicides as a leading cause of injury death from 2008 onward. 3 Likewise, unintentional overdose deaths outnumbered motor vehicle crash deaths in Australia in 2011. 4 In Europe, rates have been stable since 2005, but most European countries also have high overdose rates. For example, overdose rates of more than 20 deaths per million are found in 14 of 30 European countries, and rates of more than 40 deaths per million in 7 countries. 5 Until recently, drug overdoses were seen as a substance abuse or law enforcement issue and not as a public health problem. 1 However, partly because of the increasing involvement of legal prescription drugs such as prescription opioids in drug overdoses, public health professionals have become more interested in the topic and in diminishing the societal burden posed by unintentional overdoses. 1 Although drug overdose deaths attract much public attention, 1,6–8 there are substantial consequences of nonfatal overdose, including cardiac and muscular problems, cognitive impairment, renal failure, hearing loss, and injuries sustained during overdose. 9,10 Health care costs associated with overdose treatment are also substantial. From 1999 to 2008, hospitalization rates for overdoses in the United States increased by 55%, costing about $737 million in 2008. 11 There are little data available on drug overdose hospitalization costs in countries other than the United States. Drug overdose can be defined as happening when someone . . . collapses, has blue skin, has convulsions, has difficulty breathing, loses consciousness, cannot be woken up, has a heart attack or dies while using drugs. 12 (p704) This definition has been used widely across the literature. 13–16 Unintentional drug overdoses are unique among causes of morbidity and mortality in 2 respects. First, unintentional overdose deaths are rarely instantaneous and drug users rarely overdose alone. As such, for the most part, overdose deaths are avoidable deaths. For example, those who witness an overdose episode can call for help and apply first aid measures. 16 Opioid overdoses are preventable through the administration of naloxone, which can reverse the effect of opioids and can revive the individual. 16–18 Second, drug overdoses are inevitably and inextricably linked to the surrounding environment, particularly in the centrality of drug availability as a necessary (but insufficient) determinant of overdose. 19–23 Considering these observations that overdose is preventable and linked to surrounding environment, drug overdoses should be of concern to public health, both from the point of view of understanding their determinants and from the point of view of encouraging interventions to mitigate their consequences. A systematic review of the drug overdose literature can help clarify what we know about unintentional drug overdoses and areas in which we have gaps in scholarship. Although reviews have been written about overdoses caused by particular types of drugs (e.g., prescription opioids, heroin, methadone), 24–27 in certain places (e.g., Utah), 28 on suicidal versus accidental overdose, 29 or on overdoses among recently released prisoners, 30 we are not aware of any global review of unintentional drug overdoses with the goal of synthesizing the prevalence, time trends, mortality rates, and correlates of drug overdose worldwide.
