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Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and in-juries and healthy life expectancy (HALE) for 188 countries, 1990-2013: quantifying the epidemio-logical transition Status
Background
The global burden of diseases, injuries and risk factors 2013 study (GBD 2013) seeks to synthesize all
available epidemiological data using a coherent measurement framework, standardized estimation
methods, and transparent data sources to facilitate comparisons of health loss across causes, age‐sex
groups, and geographies and over time. The GBD can be used to generate summary measures such as
disability adjusted life years (DALYs) and healthy life expectancy (HALE) that facilitate comparative
assessments of broad epidemiological patterns across countries and time. These summary measures can
also be used to quantify the component of variation in epidemiology that is related to socio‐
demographic development.
Methods
We used the published GBD 2013 age‐specific mortality, years of life lost (YLLs) and years lived with
disability (YLDs) to compute DALYs and HALE for 1990, 1995, 2000, 2005, 2010, and 2013 for 188
countries. HALE was computed using the Sullivan method; 95% uncertainty intervals reflect uncertainty
in age‐specific death rates and YLDs per capita for each country, age, sex, and year. DALYs for 306 causes
for each country were computed as the sum of YLLs and YLDs; 95% uncertainty intervals reflect
uncertainty in YLL and YLD rates. Analysis of variance (ANOVA) using hierarchical regression was applied
to DALY rates by cause to decompose variance related to socio‐demographic status, GBD region, country
variation within regions, and unexplained.
Findings
Life expectancy at birth for the world for both sexes combined increased from 65.3 (65.0‐65.6) in 1990
to 71.5 (71.0‐71.9) in 2013, whereas over the same interval HALE at birth for both sexes combined
increased from 56.9 (54.5‐59.1) to 62.3 (59.7‐64.8). Global DALYs numbers, rates and age‐standardized
rates for communicable, maternal, neonatal and nutritional causes have been declining from 1990 to
2013. Non‐communicable disease DALY numbers are increasing, DALY rates are nearly constant and age‐
standardized DALYs are declining. From 2005 to 2013, the number of DALYs increased for a large
number of specific non‐communicable diseases and for dengue, food borne trematodes and
leishmaniasis (although in absolute terms these latter increases were small) and DALYs decreased for
nearly all other causes. By 2013, the five leading causes of DALYs were ischemic heart disease, lower
respiratory infections, cerebrovascular disease, low back & neck pain, and road injuries. SDS explains
more than 50% of the variance for diarrhea, LRI and other common infectious diseases; maternal
disorders; neonatal disorders; nutritional deficiencies, and musculoskeletal disorders. SDS explains very
little of the variance in DALY rates for HIV/AIDS and tuberculosis; neglected tropical diseases;
neoplasms; cardiovascular diseases; chronic respiratory diseases; diabetes, urogenital, blood, and
endocrine diseases; and cirrhosis along with self‐harm, interpersonal violence, forces of nature, war and
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legal intervention. A predictable shift in burden from YLLs to YLDs is associated with higher SDS driven
by declines in YLLs and increases in YLDs from musculoskeletal disorders, neurological disorders and
mental and substance abuse disorders. Country specific estimates of life expectancy and HALE show
smaller increases in HALE than life expectancy in most countries. Leading causes of DALYs are highly
variable across countries.
Interpretation
Global health is improving. Population growth and aging drive up numbers of DALYs and crude rates
remain relatively constant highlighting that progress in health does not mean less demands on health
systems. The epidemiological transition interpreted as the structured change in burden with rising SDS is
a useful construct but there is tremendous variation in burden of disease that is not associated with SDS
highlighting the need for country‐specific assessments of DALYs and HALE to inform health policy
debates.