Alcohol a Major Contributor to Global Disease Burden

Batya Swift Yasgur, MA, LSW

November 12, 2018

Alcohol and drug use disorders are rising and are significantly increasing the global burden of disease, new research shows.

Investigators at the National Health and Medical Research Council, National Drug and Alcohol Research Center, University of New South Wales, Sydney, Australia, found that alcohol use disorders are now the most prevalent of all substance use disorders (SUDs), with 100.4 million estimated cases worldwide.

The results show that globally, the most common drug use disorders are cannabis dependence, at 22.1 million cases, and opioid dependence, with 26.8 million cases.

"We provide clear comparative analysis of alcohol and drug epidemiology and attributable burden, which has generated clear evidence that both the magnitude and relative contribution of alcohol and drug use vary widely geographically," senior author Louisa Degenhardt, PhD, professor of epidemiology and principle research fellow, National Health and Medical Research Council, National Drug and Alcohol Research Center, University of New South Wales, told Medscape Medical News.

"Existing interventions that are known to reduce the varied causes of burden exist, but the challenge is to scale up these interventions, which remains even in well-resourced settings," she said.

The study was published online November 1 in Lancet Psychiatry.

Geographic, Economic Differences

Since 1993, estimates of the causes of global disease burden have used disability of adjusted life-years (DALYs), which combine a measure of disease burden caused by premature mortality (years of life lost [YLLs]) and burden due to disability (years of life lived with disability [YLDs]), the authors note.

This comparative risk assessment approach, which was developed for the Institute for Health Metrics and Evaluation's global burden of diseases research, "provides a conceptual framework for population risk assessment of exposures to risk factors and their attributable health burden," the researchers state.

Alcohol and drugs are included as risk factors in this approach.

To calculate global and regional estimates of the prevalence of alcohol and drug dependence and to estimate global disease burden attributable to these conditions, the investigators analyzed data from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016.

Studies spanned from 1990 to 2016 and included 195 countries within 21 regions and seven super-regions.

The investigators found that close to 100 million DALYs were attributable to alcohol use, and almost 32 million to drug use. The burden varied substantially across geographical locations, largely because of the effect of substance use on other health patterns.

The alcohol-attributable burden was highest in countries with low and middle-high sociodemographic index (SDI) levels. Drug-related burden increased with higher SDI level.

The researchers present global and regional estimates of alcohol and drug use and report disease burden attributable to each.

They also summarize the burden due to substances as risk factors for other health outcomes and analyze the association between alcohol- and drug-attributable burden and SDI quintiles.

Population Growth a Major Driver

SUDs were defined according to DSM-IV and ICD-10 diagnostic criteria and included dependence on opioids, cocaine, amphetamine, cannabis, and alcohol; fetal alcohol syndrome; and a "residual category" of "other" drug use disorders.

Input data on causes of death obtained from vital registration, verbal autopsy, and surveillance databases were used to calculate YLLs. Systematic literature reviews were used to calculate YLDs.

To quantify the severity of the health loss associated with a particular illness or injury, the researchers applied disability weights to the prevalence of that condition.

The authors define SDI as "the geometric mean of total fertility rate, income per capita, and mean years of education among individuals aged 15 years and older."

Worldwide, in 2016, alcohol dependence was the most prevalent of the SUDs. The most common drug use disorders were cannabis dependence and opioid dependence.

From 1990 to 2016, the global prevalence of all SUDs increased for both men and women, but age-standardized prevalence for all SUDs (with the exception of "other" drug use disorders) was significantly higher for men.

The researchers found "substantial regional variations" in the estimated prevalence of SUDs, with Australasia among the regions with the highest age-standardized prevalence across all drug use disorders and age-standardized prevalence of amphetamine dependence.

The highest prevalence of cannabis, cocaine, and opioid dependence was found in high-income North America. The highest prevalence of alcohol use disorders was found in Eastern Europe.

The "substantial" increase in the number of people with SUDs has been driven by population growth and population aging, the authors suggest.

Alcohol-Related Disability

Global DALYs attributable to alcohol use were highest for injuries (21.0 million), cardiovascular diseases (20.8 million), and cancers (14.8 million).

Drug-attributable DALYs, on the other hand, were highest for drug use disorders (20.4 million), cancers (1.6 million), and cirrhosis (4.8 million), which was driven by chronic hepatitis C infection associated with injected drug use.

There were similar patterns for deaths, YLLs, and YLDs, with 2.8 million deaths overall attributable to alcohol use and 452,000 deaths attributable to drug use.

The alcohol-attributable burdens were found most in Eastern Europe and Southern sub-Saharan Africa. The highest drug-attributable burdens were found in Eastern Europe as well as high-income North America.

Of all DALYs in 2016, 99.2 million (4.2%) were attributable to alcohol use, and 31.8 million (1.3%) were attributable to drug use.

Moreover, alcohol accounted for 76% of all substance-use-attributable DALYs globally.

Drugs accounted for a higher percentage of substance-use-attributable DALYs than alcohol in high-income North America as well as North Africa and the Middle East (53% and 69% of total alcohol- and drug-attributable DALYs, respectively).

There were great regional variations in the proportion of DALYs attributable to alcohol and drug use and the contribution of each to overall DALYs, with the largest alcohol-attributable burden found in Eastern and Central Europe and the smallest in North Africa, the Middle East, and Western sub-Saharan Africa.

Drug Use Data

Drug use accounted for the highest proportion of DALYs in high-income North America, Eastern Europe, and Australasia.

Disease burden attributable to alcohol and drug use was strongly associated with socioeconomic development. Burden composition varied across SDI quintiles.

Tuberculosis and lower respiratory infections were "considerable" causes of burden due to alcohol use in low SDI countries. In middle SDI and high-middle SDI countries, alcohol-attributable cardiovascular disease burden was higher.

In low SDI countries, compared to high-middle SID countries, HIV/AIDS was a larger cause of drug-attributable burden, whereas the consequences of chronic hepatitis C virus infection, including cirrhosis and liver cancer, were greater in countries with higher SDI.

"We produced the first estimates analyzing the association between alcohol- and drug-attributable burden and countries' SDI [and found that] the burden attributable to alcohol and drug use is strongly associated with SDI," said Degenhardt.

"Consequences of alcohol use other than AUD [alcohol use disorder] were much larger causes of disease burden, and many of these were more common in countries with a lower SDI," she added.

On the other hand, "drug-attributable burden was higher in countries with higher SDI, and the majority of this was due to drug use disorder," she said.

Early Intervention Needed

Commenting on the study for Medscape Medical News, Linda Richter, PhD, director of policy research and analysis, Center on Addiction, New York City, who was not involved in the research, said it "clearly demonstrates that SUDs are highly prevalent throughout the world, with rates on the rise, causing substantial disease burden across the globe."

The findings have important take-home messages, she said.

"Most health professionals do not take it upon themselves to educate patients about the risk of alcohol and drug use, advocate for and promote policies aimed and reducing the accessibility of these substances especially to youth, or adequately screen for alcohol or other drug use," she said.

She emphasized that "detecting these problems early and intervening appropriately can help reduce the incidence of SUDs, the burden of disease, and the need for more extensive and costly interventions."

In accompanying editorial by Catherine Gray, author of The Unexpected Joy of Being Sober , recommended "mandatory health labeling on alcohol."

She also notes that the current report provides "irrefutable proof that alcohol is creating a global health epidemic....

"It is easy for the whirl of big data to obscure the effect of human loss, so when you splice that huge figure down, it amounts to 320 deaths per hour. Or in the 60 seconds it takes you to make a cup of tea, another five people have died from alcohol," Gray writes.

The study was funded by the Bill and Melinda Gates Foundation and the Australian National Health and Medical Research Council. Funding to individual authors is listed in the original article. Dr Degenhardt has received grants from Mundipharma, Indivior, and Seqirus outside the submitted work. The other study authors, Dr Gray, and Richter have disclosed no relevant financial relationships.

Lancet Psychiatry. Published online November 1, 2018. Full text, Editorial

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