Elsevier

The Lancet

Volume 382, Issue 9904, 9–15 November 2013, Pages 1564-1574
The Lancet

Articles
Global burden of disease attributable to illicit drug use and dependence: findings from the Global Burden of Disease Study 2010

https://doi.org/10.1016/S0140-6736(13)61530-5Get rights and content

Summary

Background

No systematic attempts have been made to estimate the global and regional prevalence of amphetamine, cannabis, cocaine, and opioid dependence, and quantify their burden. We aimed to assess the prevalence and burden of drug dependence, as measured in years of life lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life years (DALYs).

Methods

We conducted systematic reviews of the epidemiology of drug dependence, and analysed results with Global Burden of Diseases, Injuries, and Risk Factors Study 2010 (GBD 2010) Bayesian meta-regression technique (DisMod-MR) to estimate population-level prevalence of dependence and use. GBD 2010 calculated new disability weights by use of representative community surveys and an internet-based survey. We combined estimates of dependence with disability weights to calculate prevalent YLDs, YLLs, and DALYs, and estimated YLDs, YLLs, and DALYs attributable to drug use as a risk factor for other health outcomes.

Findings

Illicit drug dependence directly accounted for 20·0 million DALYs (95% UI 15·3–25·4 million) in 2010, accounting for 0·8% (0·6–1·0) of global all-cause DALYs. Worldwide, more people were dependent on opioids and amphetamines than other drugs. Opioid dependence was the largest contributor to the direct burden of DALYs (9·2 million, 95% UI 7·1–11·4). The proportion of all-cause DALYs attributed to drug dependence was 20 times higher in some regions than others, with an increased proportion of burden in countries with the highest incomes. Injecting drug use as a risk factor for HIV accounted for 2·1 million DALYs (95% UI 1·1–3·6 million) and as a risk factor for hepatitis C accounted for 502 000 DALYs (286 000–891 000). Suicide as a risk of amphetamine dependence accounted for 854 000 DALYs (291 000–1 791 000), as a risk of opioid dependence for 671 000 DALYs (329 000–1 730 000), and as a risk of cocaine dependence for 324 000 DALYs (109 000–682 000). Countries with the highest rate of burden (>650 DALYs per 100 000 population) included the USA, UK, Russia, and Australia.

Interpretation

Illicit drug use is an important contributor to the global burden of disease. Efficient strategies to reduce disease burden of opioid dependence and injecting drug use, such as delivery of opioid substitution treatment and needle and syringe programmes, are needed to reduce this burden at a population scale.

Funding

Australian National Health and Medical Research Council, Australian Government Department of Health and Ageing, Bill & Melinda Gates Foundation.

Introduction

Illicit drugs are drugs whose non-medical use has been prohibited under international drug control treaties.1, 2 They include the plant-based drugs heroin, cocaine, and cannabis, synthetic drugs such as amphetamines, and pharmaceutical drugs such as opioids and benzodiazepines.

The health risks of illicit drug use increase with the frequency and quantity of drugs used. Drug dependence is defined by the International Classification of Diseases 10th Revision (ICD-10)3 as the presence of three or more indicators of dependence for at least a month within the previous year. These indicators consist of a strong desire to take the substance, impaired control over use, a withdrawal syndrome on ceasing or reducing use, tolerance to the effects of the drug, the need for larger doses to achieve the desired psychological effect, a disproportionate amount of time spent by the user obtaining, using, and recovering from drug use, and persistence of drug taking despite the problems that occur. Rates of illicit drug dependence are thought to be increased in developed countries,4 but no global estimates have been made to date.

Since 1993, estimates of the causes of global disease burden have used the disability-adjusted life year (DALY)5 to combine disease burden attributable to premature mortality (years of life lost [YLLs]) with that attributable to disability (years of life lived with disability [YLDs]). The operationalised definition of illicit drug use has changed since the original Global Burden of Disease (GBD) study; drug use in GBD 1990 was defined as dysfunctional and harmful drug use overall, without specifying drug type.6

In 2002, the GBD comparative risk assessment (CRA) exercise7 estimated the proportion of disease burden attributable to alcohol, tobacco, and illicit drug use.7 WHO estimated that amphetamine, cocaine, and opioid use accounted for 0·9% of global DALYs in 2004.8 However, this proportion was an underestimate9 because it did not include burden attributable to cannabis, to infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) from injecting drug use, or drug-related violence (homicide).10

The Global Burden of Diseases, Injuries, and Risk Factors Study 2010 (GBD 2010)11 calculated the burden of illicit drug dependence separately for amphetamines, cocaine, opioids, and cannabis, and assessed more outcomes than did the CRA exercise. This report summarises data for the prevalence and disease burden attributable to these illicit drugs in GBD 2010 and the findings of the CRA12 for illicit drug use as a risk factor for other health outcomes. We aim to present the global estimates and regional variation in the prevalence of amphetamine, cannabis, cocaine, and opioid dependence; report YLDs, YLLs, and DALYs attributable to each of these forms of drug dependence; and summarise additional burden due to illicit drug use as a risk factor for other health outcomes.

Section snippets

Overview

The case definitions used for amphetamine, cannabis, cocaine and opioid dependence were based on the International classification of diseases (ICD)13 and the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, version 4 (DSM-IV).14 To estimate burden of disease attributable to illicit drug use and dependence, we aggregated disorder-specific epidemiological data and disability weights15 to calculate prevalent YLDs;16 multiplied disorder-specific estimates of

Results

Opioid and amphetamine dependence were the two most common forms of illicit drug dependence worldwide, although millions of people were also dependent on cannabis or cocaine (table 1). Most individuals dependent on drugs were male (64% each for cannabis and amphetamines and 70% each for opioids and cocaine).

Geographical distribution of individuals with drug dependence resulted from variations in prevalence and country populations (table 1). We estimated that 9·3 million individuals with

Discussion

To our knowledge, this study is the first attempt to estimate the global, regional, and country level prevalence of dependence and burden of disease attributable to drug dependence for four major illicit drug types (amphetamines, cannabis, cocaine, and opioids). Several key findings emerged. First, age and sex patterns of dependence and burden were striking. All forms of drug dependence and disease burden were highest in men aged 20–29 years. These disorders adversely affect young adults at a

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