Global Burden of Disease: Mental Disorders and Illicit Drug Use Expert Group

NDARC Staff

Louisa Degenhardt, Paul Nelson and Chiara Bucello

Other Investigators

Harvey Whiteford, Amanda Baxter and An Pham (Queensland Centre for Mental Health Research, University of Queensland)

Rationale

The original Global Burden of Disease (GBD) Study was commissioned by the World Bank in 1991 and provided burden of disease estimates for the year 1990. New estimates for 2001 were published as part of the second revision of the Disease Control Priorities Project.

The principle guiding the burden of disease approach is that best estimates of incidence, prevalence, and mortality can be generated through the careful analysis of all available sources of information in a country or region (corrected for bias). The disability-adjusted life year, or DALY, was developed to assess burden of disease: a time-based measure that combines years of life lost due to premature mortality and years of life lost due to time lived in health states less than ideal.

The current study will involve a complete systematic assessment of the data on all diseases and injuries, and produce comprehensive and comparable estimates of the burden of diseases, injuries and risk factors for two time periods: 1990 and 2005. Improved techniques and new data will be used.

As part of the GBD Study, researchers at NDARC and the Queensland Centre for Mental Health Research at the University of Queensland are currently undertaking research that will determine the global burden of disease of illicit drug use and dependence, and mental health disorders. This represents the work of the Mental Disorders and Illicit Drug Use Expert Group.

Aims

The GBD study has two major objectives:

1. to produce estimates of the burden of diseases and injuries, and to assess risk factors, for the years 1990 and 2005 organised in 21 regions covering the globe
2. to develop a series of tools for use by specific audiences, to standardise and broaden burden of disease research and analysis, and to produce publications tailored to policymakers and a non-research audience

As part of the first GBD Study objective, the Mental Disorders and Illicit Drug Use Expert Group aims to produce estimates of the burden of disease associated with mental health disorders and illicit drug use and dependence.

Design and Method

The GBD Study will take three years to complete. The project will examine more than 175 diseases and injuries, and more than 45 risk factors, in 21 regions of the world.

Systematic reviews of the prevalence, incidence and duration of mental health disorders and associated mortality and disabling sequelae will be conducted by the Mental Disorders and Illicit Drug Use Expert Group. Additionally, exposure and effects of risk factors will be assessed. Expert Groups will communicate their figures at defined intervals with other Expert Groups and with the Core Team to ensure consistency across conditions, and will be subjected to external peer review.

NDARC is collecting data on the following drug groups:

• heroin and other opioids
• amphetamine type stimulants
• cocaine
• cannabis

Progress

Systematic reviews of mortality, prevalence, incidence and remission/duration of dependence on heroin and other opioids, amphetamine type stimulants, cocaine and cannabis have been conducted, and data extracted. The comparative risk assessment for illicit drugs is underway.

Benefits

The GBD study will provide four key benefits as a source of accurate knowledge and a vital tool for informed decision-making.

1. Systematic and objective analysis is ensured by separating epidemiological assessment from advocacy, creating evidence-based pictures of health patterns that can subsequently motivate responsible policy formulation and research
2. Balanced assessment of health problems, which combines information on disease and risk factor causes of premature mortality, morbidity, and disability
3. Assessment of the magnitude of health problems using standard units of measurement, such as disability-adjusted life years (DALYs)
4. Focus on education, training and transparency

Output

The GBD Study is divided into seven major activities with milestones that span the length of the project. Each major activity has been carefully planned to correspond to the work in other activities so that each area progresses at a similar pace. The activities are:

1. Disease, injury and risk factor epidemiological review
2. Mortality estimation
3. Cause of death estimation using population data sources
4. Disability weight measurement and comorbidity corrections
5. Comparative risk assessment
6. Harmonize GBD estimates
7. Creation of curricula and tools and dissemination of results and products

NDARC has produced a number of discussion papers on various aspects of the GBD study. These can be accessed from the publications page of the GBD website