Alcohol, tobacco, and illegal drug use cause considerable morbidity and mortality, but good cross-national epidemiological data are limited. This paper describes such data from the first 17 countries participating in the World Health Organization's (WHO's) World Mental Health (WMH) Survey Initiative.
Methods and Findings
Household surveys with a combined sample size of 85,052 were carried out in the Americas (Colombia, Mexico, United States), Europe (Belgium, France, Germany, Italy, Netherlands, Spain, Ukraine), Middle East and Africa (Israel, Lebanon, Nigeria, South Africa), Asia (Japan, People's Republic of China), and Oceania (New Zealand). The WHO Composite International Diagnostic Interview (CIDI) was used to assess the prevalence and correlates of a wide variety of mental and substance disorders. This paper focuses on lifetime use and age of initiation of tobacco, alcohol, cannabis, and cocaine. Alcohol had been used by most in the Americas, Europe, Japan, and New Zealand, with smaller proportions in the Middle East, Africa, and China. Cannabis use in the US and New Zealand (both 42%) was far higher than in any other country. The US was also an outlier in cocaine use (16%). Males were more likely than females to have used drugs; and a sex–cohort interaction was observed, whereby not only were younger cohorts more likely to use all drugs, but the male–female gap was closing in more recent cohorts. The period of risk for drug initiation also appears to be lengthening longer into adulthood among more recent cohorts. Associations with sociodemographic variables were consistent across countries, as were the curves of incidence of lifetime use.
Globally, drug use is not distributed evenly and is not simply related to drug policy, since countries with stringent user-level illegal drug policies did not have lower levels of use than countries with liberal ones. Sex differences were consistently documented, but are decreasing in more recent cohorts, who also have higher levels of illegal drug use and extensions in the period of risk for initiation.
Louisa Degenhardt and colleagues report an international survey of 17 countries that finds clear differences in drug use across different regions of the world.
Understanding how much disability and death a particular disease causes (known as the “burden of disease”) is important. Knowing the burden of a disease in a country contributes to the development of healthier nations by directing strategies and policies against the disease. Researchers' understanding of the burden of diseases across different countries was piecemeal until the 1990 launch of a special World Health Organization (WHO) project, the Global Burden of Disease Project. In 2002, on the basis of updated information from this ongoing project, the WHO estimated that 91 million people were affected by alcohol use disorders and 15 million by drug use disorders.
Why Was This Study Done?
It is widely accepted that alcohol, tobacco, and illegal drug use are linked with a considerable amount of illness, disability, and death. However, there are few high-quality data quantifying the amount across different countries, especially in less-developed countries. The researchers therefore set out to collect basic patterns of alcohol, tobacco, cannabis, and cocaine use in different countries. They documented lifetime use of these substances in each county, focusing on young adults. They also wanted to examine the age of onset of use and whether the type of drugs used was affected by one's social and economic status.
What Did the Researchers Do and Find?
Data on drug use were available from 54,069 survey participants in 17 countries. The 17 countries were determined by the availability of collaborators and on funding for the survey. Trained lay interviewers carried out face-to-face interviews (except in France where the interviews were done over the telephone) using a standardized, structured diagnostic interview for psychiatric conditions. Participants were asked if they had ever used (a) alcohol, (b) tobacco (cigarettes, cigars or pipes), (c) cannabis (marijuana, hashish), or (d) cocaine. If they had used any of these drugs, they were asked about the age they started using each type of drug. The age of first tobacco smoking was not assessed in New Zealand, Japan, France, Germany, Belgium, The Netherlands, Italy, or Spain. The interviewers also recorded the participants' sex, age, years of education, marital status, employment, and household income.
The researchers found that in the Americas, Europe, Japan, and New Zealand, alcohol had been used by the vast majority of survey participants, compared to smaller proportions in the Middle East, Africa, and China. The global distribution of drug use is unevenly distributed with the US having the highest levels of both legal and illegal drug use among all countries surveyed. There are differences in both legal and illegal drug use among different socioeconomic groups. For example, males were more likely than females to have used all drug types; younger adults were more likely than older adults to have used all drugs examined; and higher income was related to drug use of all kinds. Marital status was found to be linked only to illegal drug use—the use of cocaine and cannabis is more likely in people who have never been married or were previously married. Drug use does not appear to be related to drug policy, as countries with more stringent policies (e.g., the US) did not have lower levels of illegal drug use than countries with more liberal policies (e.g., The Netherlands).
What Do These Findings Mean?
These findings present comprehensive and useful data on the patterns of drug use from national samples representing all regions of the world. The data will add to the understanding of the global burden of disease and should be useful to government and health organizations in developing policies to combat these problems. The study does have its limitations—for example, it surveyed only 17 of the world's countries, within these countries there were different rates of participation, and it is unclear whether people accurately report their drug use when interviewed. Nevertheless, the study did find clear differences in drug use across different regions of the world, with the US having among the highest levels of legal and illegal drug use of all the countries surveyed.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050141.
Facts and figures on alcohol are available from the World Health Organization, including information about the burden of disease worldwide as a result of alcohol
Information on the management of substance abuse is available from WHO
Information on the Global Burden of Disease Project is also available from WHO
Researchers from the University of New South Wales, Australia and the University of Queensland co-chair, sponsors the Global Burden of Disease Mental Disorders and Illicit Drug Use Expert Group, which examines illicit drug use and disorders
The UN World Drug Report is available from the UN Office on Drugs and Crime
The University of New South Wales also runs the Secretariat for the Reference Group to the United Nations on HIV and Injecting Drug Use