With respect to the health care sector, what obstacle to prevention do you feel is the most important and what strategy to overcome this obstacle will be the most impactful, and why?
Research
Original Investigation
The State of US Health, 1990-2010
Burden of Diseases, Injuries, and Risk Factors
US Burden of Disease Collaborators
Editorial page 585
IMPORTANCE Understanding the major health problems in the United States and how they
are changing over time is critical for informing national health policy.
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OBJECTIVES To measure the burden of diseases, injuries, and leading risk factors in the
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United States from 1990 to 2010 and to compare these measurements with those of the 34
countries in the Organisation for Economic Co-operation and Development (OECD) countries.
DESIGN We used the systematic analysis of descriptive epidemiology of 291 diseases and
injuries, 1160 sequelae of these diseases and injuries, and 67 risk factors or clusters of risk
factors from 1990 to 2010 for 187 countries developed for the Global Burden of Disease 2010
Study to describe the health status of the United States and to compare US health outcomes
with those of 34 OECD countries. Years of life lost due to premature mortality (YLLs) were
computed by multiplying the number of deaths at each age by a reference life expectancy at
that age. Years lived with disability (YLDs) were calculated by multiplying prevalence (based
on systematic reviews) by the disability weight (based on population-based surveys) for each
sequela; disability in this study refers to any short- or long-term loss of health.
Disability-adjusted life-years (DALYs) were estimated as the sum of YLDs and YLLs. Deaths
and DALYs related to risk factors were based on systematic reviews and meta-analyses of
exposure data and relative risks for risk-outcome pairs. Healthy life expectancy (HALE) was
used to summarize overall population health, accounting for both length of life and levels of ill
health experienced at different ages.
RESULTS US life expectancy for both sexes combined increased from 75.2 years in 1990 to
78.2 years in 2010; during the same period, HALE increased from 65.8 years to 68.1 years.
The diseases and injuries with the largest number of YLLs in 2010 were ischemic heart
disease, lung cancer, stroke, chronic obstructive pulmonary disease, and road injury.
Age-standardized YLL rates increased for Alzheimer disease, drug use disorders, chronic
kidney disease, kidney cancer, and falls. The diseases with the largest number of YLDs in 2010
were low back pain, major depressive disorder, other musculoskeletal disorders, neck pain,
and anxiety disorders. As the US population has aged, YLDs have comprised a larger share of
DALYs than have YLLs. The leading risk factors related to DALYs were dietary risks, tobacco
smoking, high body mass index, high blood pressure, high fasting plasma glucose, physical
inactivity, and alcohol use. Among 34 OECD countries between 1990 and 2010, the US rank
for the age-standardized death rate changed from 18th to 27th, for the age-standardized YLL
rate from 23rd to 28th, for the age-standardized YLD rate from 5th to 6th, for life expectancy
at birth from 20th to 27th, and for HALE from 14th to 26th.
CONCLUSIONS AND RELEVANCE From 1990 to 2010, the United States made substantial
progress in improving health. Life expectancy at birth and HALE increased, all-cause death
rates at all ages decreased, and age-specific rates of years lived with disability remained
stable. However, morbidity and chronic disability now account for nearly half of the US health
burden, and improvements in population health in the United States have not kept pace with
advances in population health in other wealthy nations.
JAMA. 2013;310(6):591-608. doi:10.1001/jama.2013.13805
Published online July 10, 2013.
Members of the US Burden of
Disease Collaborators appear at the
end of this article.
Corresponding Author: Christopher
J. L. Murray, MD, DPhil, Institute for
Health Metrics and Evaluation, 2301
Fifth Ave, Ste 600, Seattle, WA 98121
(cjlm@uw.edu).
591
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Research Original Investigation
T
he United States spends the most per capita on health
care across all countries,1,2 lacks universal health coverage, and lags behind other high-income countries for
life expectancy3 and many other health outcome measures.4
High costs with mediocre population health outcomes at the
national level are compounded by marked disparities across
communities, socioeconomic groups, and race and ethnicity
groups.5,6 Although overall life expectancy has
DALYs disability-adjusted life-years
slowly risen, the increase
HALE healthy life expectancy
has been slower than for
YLDs years lived with disability
many other high-income
YLLs years of life lost due to
countries.3 In addition, in
premature mortality
some US counties, life expectancy has decreased in the past 2 decades, particularly for
women.7,8 Decades of health policy and legislative initiatives
have been directed at these challenges; a recent example is the
Patient Protection and Affordable Care Act, which is intended to address issues of access, efficiency, and quality of
care and to bring greater emphasis to population health
outcomes.9 There have also been calls for initiatives to address determinants of poor health outside the health sector including enhanced tobacco control initiatives,10-12 the food
supply,13-15 physical environment,16,17 and socioeconomic
inequalities.18
With increasing focus on population health outcomes that
can be achieved through better public health, multisectoral action, and medical care, it is critical to determine which diseases, injuries, and risk factors are related to the greatest losses
of health and how these risk factors and health outcomes are
changing over time. The Global Burden of Disease (GBD)
framework19 provides a coherent set of concepts, definitions,
and methods to do this. The GBD uses multiple metrics to quantify the relationship of diseases, injuries, and risk factors with
health outcomes, each providing different perspectives. Burden of disease studies using earlier variants of this approach
have been published for the United States for 199620-22 and for
Los Angeles County, California.23 In addition, 12 major risk factors have also been compared for 2005.24
In this report, we use the GBD Study 2010 to identify the
leading diseases, injuries, and risk factors associated with the
burden of disease in the United States, to determine how these
health burdens have changed over the last 2 decades, and to
compare the United States with other Organisation for Economic Co-operation and Development (OECD) countries.
Methods
The GBD 2010, a collaborative effort involving 488 scientists
from 50 countries, quantified health loss from 291 diseases and
injuries, 1160 clinical sequelae of these diseases and injuries,
and 67 risk factors or clusters of risk factors for 187 countries
from 1990 to 2010. The overall aim of the GBD 2010 was to synthesize the world’s knowledge of descriptive epidemiology to
facilitate comparisons across problems, over time, and across
countries. Methods and summary results from the GBD 2010
for the world and 21 regions have been published.3,19,25-31 Sev592
The State of US Health, 1990-2010
Box. Glossary of Terms
Disability-adjusted life-years: a summary metric of population
health. DALYs represent a health gap and, as such, measure the state
of a population’s health compared to a normative goal. The goal is for
individuals to live the standard life expectancy in full health. DALYs
are the sum of 2 components: years of life lost (YLLs) and years lived
with disability (YLDs).
Healthy life expectancy: the number of years that a person at a given
age can expect to live in good health, taking into account mortality
and disability.
Years lived with disability: computed as the prevalence of different disease sequelae and injury sequelae multiplied by disability
weights for that sequela. Disability weights are selected on the basis
of surveys of the general population about the health loss associated with the health state related to the disease sequela.
Years of life lost due to premature mortality: computed by multiplying the number of deaths at each age by a standard life expectancy at that age. The standard selected represents the normative
goal for survival and has been computed based on the lowest recorded death rates across countries in 2010.
eral studies focusing on results for a specific disease or risk factor have also been published or are in preparation.32-34 Because the GBD 2010 uses a standardized approach for 187
countries, the results can be used to benchmark population
health outcomes across different groups of nations. National
burden of disease studies including a benchmarking component using the GBD 2010 have been completed for the United
Kingdom32 and China.35 Details on the data, approaches to enhancing data quality and comparability, and statistical modeling and metric s for the GBD 2010 are published
elsewhere.3,19,25-27,29-31
The GBD 2010 cause list has 291 diseases and injuries, which
are organized in a hierarchy with up to 4 levels of disaggregation. We identified the key sequelae for each disease or injury. Sequelae could include the disease, such as diabetes, or
the outcomes associated with that disease, such as diabetic
foot, neuropathy, or retinopathy. Some clinical disorders were
classified as a disease but could also be a consequence of another disease; for example, cirrhosis secondary to hepatitis B
is a consequence of hepatitis B but was classified as a disease.
Any outcome appears in the GBD cause and sequelae list only
once to avoid double counting. The full list of risk factors, diseases, and sequelae and further details on their development
since 1991 are published elsewhere.19 In total, the study included 1160 sequelae.
The GBD 2010 uses several metrics to report results on
health loss related to specific diseases, injuries, and risk factors: deaths and death rates, years of life lost due to premature mortality (YLLs), prevalence and prevalence rates for
sequelae, years lived with disability (YLDs), and disabilityadjusted life-years (DALYs) (Box). Years of life lost are computed by multiplying the number of deaths in each age group
by a reference life expectancy at that age. The life expectancy
at birth in the reference life table is 86.0 years based on the lowest observed death rates for each age group across countries
in 2010 and is intended to be an achievable outcome.19
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The State of US Health, 1990-2010
Years lived with disability are calculated from the prevalence of a sequela multiplied by the disability weight for that
sequela, which reflects its severity on a continuum between
no loss of health (which has a disability weight of 0) and complete loss of health (which has a weight of 1.0). The meaning
of disability in the GBD differs from that in US legislation such
as the Americans with Disabilities Act; in the GBD, disability
refers to any short- or long-term health loss. DALYs are the sum
of YLLs and YLDs. The GBD uses another indicator, healthy life
expectancy (HALE), to summarize overall population health
in a single number accounting for both length of life and levels of ill health experienced at different ages.27
Estimation of prevalence for each sequela began with a systematic analysis of published studies and data sources providing information on prevalence, incidence, remission, and
excess mortality, such as the National Health and Nutrition Examination Surveys,36 State Inpatient Databases,37 the National Ambulatory Medical Care Survey,38,39 the National Hospital Ambulatory Medical Care Survey, 4 0 the Medical
Expenditure Panel Survey, 41 the National Comorbidity
Survey,42 the National Epidemiological Survey on Alcohol and
Related Conditions, and disease surveillance reports from the
Centers for Disease Control and Prevention. For most sequelae, estimates were made using a Bayesian metaregression tool developed for the GBD 2010 (DisMod-MR). The
DisMod-MR program estimates a generalized negative binomial model with nested random effects for regions and countries and fixed effects (see Vos et al25 for details on the equations and estimation procedure). Source code for DisMod-MR
is available at http://ihmeuw.org/dismod_mr. eTable 1 in the
Supplement provides the estimated prevalences for the 1160
sequelae for the United States in 2010.
For the GBD 2010, disability weights were measured for 220
unique health states that cover the 1160 disease and injury
sequelae.26 Disability weights were generated using data from
more than 30 000 respondents contacted through populationbased, random-sample surveys in the United States, Peru,
Tanzania, Bangladesh, and Indonesia and through an open
Internet survey. The US survey, conducted using computerassisted telephone interviews, consisted of 3323 respondents, and the Internet survey consisted of 7180 selfselecting respondents from the United States. Results from
population surveys in developing countries and the United
States were highly consistent, suggesting a common construct of health; likewise, the results from the well-educated
respondents to the Internet survey were highly consistent with
the population-based samples. For example, the correlation
between results from the United States and from the combined sample was 0.97.26 The 220 disability weights used in this
study and the lay descriptions used to elicit choices from survey respondents are published elsewhere.26 Uncertainty in the
disability weight for each sequela was propagated into the estimates of YLDs for each disease and injury using standard
simulation methods.43 Information on age-specific mortality
rates and on overall age-specific YLDs per person was combined into an overall measure of HALE, using a standard approach to extending the life table to capture adjustments for
nonfatal health outcomes.27
Original Investigation Research
We estimated the deaths or DALYs related to the 67 risk factors or clusters of risk factors (eTables 7 and 8 in the Supplement) following the conceptual framework for risk factors developed for the GBD, which identifies 3 layers of factors in a
causal web: distal socioeconomic, proximal behavioral and environmental, and physiological and pathophysiological
causes.44 Computation follows 3 key steps.
In the first step, risk-outcome pairs were included when
evidence met the criteria for “convincing” or “probable”
evidence.45 As defined by the World Cancer Research Fund
grading system, convincing evidence is evidence from epidemiological studies showing consistent associations between
exposure and disease, with little or no evidence to the contrary. The evidence must come from a substantial number of
studies including prospective observational studies and, when
relevant, randomized controlled trials of sufficient size, duration, and quality showing consistent effects. The association should be biologically plausible, such as the effect of salt
on fluid retention, increases in blood pressure, and ultimate
effect on cardiovascular diseases. Probable evidence is defined as evidence based on epidemiological studies showing
fairly consistent associations between exposure and disease
but for which there are perceived shortcomings in the available evidence or some evidence to the contrary, which preclude a more definite judgment; for example, the effects of diets
low in seafood omega-3 fatty acids on ischemic heart disease
mortality. Shortcomings in the evidence may be any of the following: insufficient duration of trials (or studies), insufficient trials (or studies) available, inadequate sample sizes, or
incomplete follow-up. Laboratory evidence is usually supportive and the association must again be biologically plausible. Relative risks of mortality and morbidity were estimated based on meta-analyses of the scientific literature.31
eTable 2 in the Supplement provides the published relative risks
used for each of the risk factors used in the analysis.
In the second step, the distribution of each risk factor exposure in each country, age, and sex group was estimated from
published and unpublished data sources.31
In the third step, deaths or DALYs associated with risk
factors were estimated by comparing the current distribution
of exposure with a theoretical minimum risk exposure distribution (TMRED) of exposure selected for each risk factor. The
TMRED is a feasible distribution of exposure that would
minimize population health risk. For example, the theoretical minimum risk distribution for tobacco is that no one has
smoked in the past; for systolic blood pressure, it is a distribution with a mean of 110 to 115 mm Hg and a standard
deviation of 6 mm Hg. The TMRED for each risk factor is the
same for all populations; Lim et al31 provides detail on these
distributions for dichotomous and continuous risk factors.
TMREDs have been defined for each of the 14 subcomponents of diet. The overall relationship of diet with health outcomes assumes the contribution of each component is multiplicative; that is, that the individual dietary contributions are
independent.
Each risk factor or cluster of risk factors was analyzed separately such that the sum of attributable fractions (see eTable
2 in the Supplement) for a disease or injury can be greater than
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JAMA August 14, 2013 Volume 310, Number 6
593
Research Original Investigation
100%. For example, a behavioral risk factor, such as some components of diet, may operate in part through reducing blood
pressure. We included only risks for which there was convincing or probable evidence for pairs of risk factors and specific
outcomes and that had sufficient epidemiological data to estimate risk factor–specific effect sizes, eg, relative risks. These
risks included a range of behavioral, environmental, and metabolic risk factors, but distal socioeconomic factors were excluded because much of the literature on these risk factors focuses on all-cause mortality and morbidity outcomes.
Using simulation methods,46,47 we took 1000 draws (unbiased random samples) from the uncertainty distribution of
the relative risks, prevalence of exposure estimates, theoretical minimum risk distributions, and background outcome rates.
Uncertainty intervals for burden related to a risk factor were
based on computation of the results for each of the 1000 draws;
the lower bound of the 95% uncertainty interval for the final
quantity of interest is the 2.5 percentile of the distribution and
the upper bound is the 97.5 percentile of the distribution. These
uncertainty intervals reflect all sources of uncertainty, including sampling error and model parameter uncertainty, from each
component of the analysis.
For outcomes measured for specific age groups (deaths,
YLLs, YLDs, and DALYs), we directly computed agestandardized rates using the World Health Organization’s age
standard.48 For each disease, injury, or risk factor, we ranked
countries in 1990 and 2010 by the age-standardized rates for
each outcome measure. We compared US outcomes with those
of the 34 countries that are members of the OECD. These OECD
members have been used in other comparative studies for the
United States.49 For a given country and disease, injury, or risk,
we tested whether a country was significantly above the mean
of all OECD countries, indistinguishable from the mean, or below the mean; we used a 1-sided test at the P
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