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Disability‐adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010

Published December 13, 2012, in The Lancet

Abstract

The Global Burden of Disease Study 2010 (GBD 2010) has three related but distinct uses: to provide a coherent picture of which diseases, injuries, and risk factors contribute the most to health loss in a given population; to compare population health across communities and over time; and to help guide an assessment of where health information systems are strong or weak by identifying which data sources are missing, are of low quality, or are highly uncertain.
 
In this paper, results on years lost due to premature mortality (YLLs) and years lived with disability (YLDs) are combined to examine the overall burden of disease across 291 diseases and injuries by country for the period 1990 to 2010.

Analytical approach

The authors used disability‐adjusted life years (DALYs) as a summary measure of population health. DALYs are the sum of YLLs and YLDs. DALYs were calculated for 291 causes, 20 age groups, both sexes, and for 187 countries and aggregated to regional and global estimates for 21 regions for three points in time – 1990, 2005, and 2010.
 
YLLs were calculated from age‐sex‐country‐time‐specific estimates of mortality by cause, with death by standardized lost life expectancy at each age. YLDs were calculated as prevalence of 1,160 disabling conditions resulting from diseases, by age, sex, and cause, and weighted by new disability weights. Neither YLLs nor YLDs were age‐weighted or discounted.

Research findings

The total number of DALYs remained stable from 1990 (2.503 billion) to 2010 (2.490 billion), but this stable number masks rapid health transitions around the world. The top causes of disease and injury have changed greatly since 1990. Ischaemic heart disease was the leading cause of DALYs worldwide in 2010 (up from the fourth rank in 1990; increasing by 29%), followed by lower respiratory infections (top rank in 1990; 44% decline in DALYs), stroke (fifth in 1990; 19% increase, diarrheal disease (second in 1990; 51% decrease), and HIV/AIDS (33rd in 1990; 351% increase). Major depressive disorders increased from 15th to 11th rank (37% increase) and road injury from 12th to 10th rank (34% increase).
 
These changes are driven by three global forces: population growth and aging, the epidemiological transition, and the disability transition.
 
Demographic change alone, population growth and aging, is shifting the pattern of the burden of disease. Because noncommunicable diseases (NCDs) increase with age, demographic change is shifting the burden of disease toward NCDs dramatically.
 
Aging is leading to a 19.1% increase in NCDs from 1990 to 2010 while at the same time leading to a decline of 22.2% in communicable, maternal, neonatal, and nutritional causes. Demographic change is leading to a larger share of the burden of disease being in young and middle‐aged populations.
 
The epidemiological transition is leading to a progressive shift towards NCDs as the leading causes of burden. Over two decades, the burden has changed substantially from communicable, maternal, nutritional, and neonatal causes toward NCDs. The distribution of DALYs in 2010 reflected a predominance of noncommunicable diseases globally, with 54% of all DALYs resulting from these causes.
 
The third large transition is the shift toward more burden coming from diseases and injuries that cause disability rather than mortality. Musculoskeletal disorders such as low back pain, neck pain, osteoarthritis and mental and behavioural disorders such as major depression, anxiety, bipolar disorder, or alcohol use disorders are increasing steadily. Globally, 31.2% of DALYs in 2010 were from YLDs, up from 23.3% in 1990.
 
While these broad transitions are underway in many parts of the world, we cannot forget that 35% of DALYs are still due to communicable, maternal, nutritional, and neonatal causes. This highlights the unfinished agenda for dealing with deaths in the poor of pneumonia, diarrhea, malaria, HIV, tuberculosis, premature birth, and neonatal encephalopathy. While burden has dramatically shifted away from death under age 5 to death and disability in the reproductive years, a quarter of the burden is still caused by disease and injury under age 5.
 
On top of these three broad drivers of change are regional variations that can profoundly influence local patterns of disease burden. Huge differences by region are also layered over this general pattern of demographic and epidemiological change. HIV is the dominant cause of burden in eastern sub‐Saharan Africa and southern sub‐Saharan Africa. Interpersonal violence is a leading cause in central Latin America, tropical Latin America, and southern sub‐Saharan Africa. Suicide is a top ten cause of burden in high‐income Asia Pacific and eastern Europe. Cirrhosis is an important cause in central Asia, eastern and central Europe, and central Latin America. Drug use disorders are particularly important in Australasia and high‐income North America.

Policy implications

Outside of sub‐Saharan Africa, the world is undergoing rapid health transitions. Health systems need to plan appropriately for these transitions both in terms of health manpower, infrastructure, and program priorities. No longer can they afford to focus on a narrow set of conditions, such as HIV, tuberculosis, malaria, diarrhea, and pneumonia. While these conditions still represent a substantial portion of the disease burden, GBD 2010 shows that a broader approach is necessary.
 
DALYs due to Millennium Development Goals (MDGs) 4, 5, and 6 account for 60 to 70% of burden in sub‐Saharan African regions, a third of burden in south Asia and Oceania, and less than 20% in all other regions. Substantial progress has been made in reducing the MDG‐related burden in all regions outside of sub‐Saharan Africa. Post‐2015 development goals will need to articulate health targets that are broad enough to be relevant to all developing regions. One way to frame the discussion is to focus on healthy life expectancy, which calls for a specific examination within regions and within countries of the diseases, injuries, and risk factors that are preventing people from living their lives in the fullest health.
 
The profile of burden in sub‐Saharan Africa remains dominated by diarrhea, lower respiratory infections, neonatal conditions, malaria, HIV, and tuberculosis. While progress has been made since 1990, and particularly since 2005, continued special attention is needed to accelerate health progress in these regions.

 

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Citation

Murray CJL, Vos T, Lozano R, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. The Lancet. 2012 Dec 13; 380: 2197–2223.

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