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9 Research Agenda A lthough much is known about the U.S. health disadvantage, every chapter of this report has identified gaps in the evidence for docu- menting its scope, understanding its causes, and identifying effective solutions. It is clear that further research in epidemiology, demography, health services, economics, and political science is necessary to fully under- stand the root causes of the U.S. health disadvantage. The specific defi- ciencies in each topic area are too extensive to summarize here, and the literature in each field often includes articles that document specific research challenges. However, this report has identified several recurring themes that point to important priorities for research on cross-national differences in health. This chapter focuses on advancing the science for understanding the U.S. health disadvantage, but we emphasize that such efforts should not come at the expense of vitally important fields of research that focus on how to reduce morbidity and mortality from today’s leading health threats, including the nine conditions responsible for the U.S. health disadvantage documented in Part I. In general, cross-national comparisons provide only clues as to why one population is healthier than another. Investigating these important hypotheses should not detract from research on specific diseases and injuries and on effective interventions and policies to improve health outcomes in the United States. Research in the areas of biomedicine, health services, public health, social epidemiology, and the social, behavioral, and environmental sciences are all vital. Diverting support or funding for these important research endeavors to study the U.S. health disadvantage would be a fundamental mistake. 241
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242 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE We also emphasize that our call for more research should not be used as an excuse for inaction on the part of the nation. As detailed in Chapter 10, the causes of the U.S. health disadvantage are clear enough, and there is suf- ficient evidence to justify an immediate response on the part of the nation, states, and local communities. The public health and social policy priorities are evident, and interventions of proven effectiveness are known. Delaying action to wait for more data will only allow the U.S. health disadvantage to grow (see Chapter 10). Research can point to priority areas for action, but its value will depend on the quality of available cross-national data. This chapter focuses on how to build capacity for productive scholarship on international health differences and the need for an ongoing and coordinated commitment by research agencies, funding bodies, statistical agencies, and investigators. We focus on four areas: (1) data needs, (2) analytic methods development, (3) new lines of inquiry, and (4) stable research funding. BACKGROUND High-income countries currently collect extensive data on health indi- cators and a variety of factors that contribute to health and illness. The United States is among the countries with the most extensive efforts to collect health-related data using large population-based surveys. Large nationally representative population health surveys conducted by the U.S. Department of Health and Human Services include the National Health Information Survey (NHIS), the Behavioral Risk Factor and Surveillance System (BRFSS) survey, the National Health and Nutrition Examination Survey (NHANES), and the National Ambulatory Medical Care Survey (NAMCS). The BRFSS program has been systematically collecting risk fac- tor data in a state-based system for nearly three decades. It is one of the few worldwide examples of a sustained systematic collection of data that tracks risk factors over time at the population level. Population surveys conducted by other agencies are also relevant to this topic, including the decennial U.S. census, the American Community Survey, the Current Population Survey, and surveys conducted by the U.S. Department of Education. Data collection efforts in other countries range from local or provincial surveys to nationally representative survey methodologies and some coopera- tive multinational efforts to administer similar survey instruments to compa- rable populations in each country. An example of the latter is the Survey of Health, Ageing and Retirement in Europe (SHARE), the English Longitudi- nal Study on Ageing (ELSA), and the Health and Retirement Study (HRS). For a detailed list of data sets that are available for research (see Table 9-1). In the United States, the National Institutes of Health (NIH)—and the National Institute on Aging in particular—has played a leadership role in
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TABLE 9-1 Publicly Available Databases for Aging-Related Secondary Analyses in the Behavioral and Social Sciences STUDY FEATURES Baseline Sample Size Start Year End Year Longitudinal International Minority Oversample(s) Anthropometric Measures Biospecimens DATABASE AVAILABLE DATA SETS Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) 2,802 1999 2011 X X X X Aging, Status, and the Sense of Control (ASOC) 2,593 1995 2001 X Alameda County Health and Ways of Living Study 6,928 1965 1999 X X Americans Changing Lives Study (ACL) 3,617 1986 Pres X X Assessment of Doctor-Elderly Patient Encounters (ADEPT) 46 1998 2001 X X The Australian Longitudinal Study of Ageing (ALSA) 2,087 1992 2010 X X X X Census Microdata Samples Project (also known as The Status of Older ~1 million 1989 1992 X X Persons in UNECE Countries) The Charleston Heart Study (CHS) 2,283 1960 Pres X X X China Health and Retirement Longitudinal Study (CHARLS) 17,000 2008 Pres X X X X Chinese Longitudinal Healthy Longevity Survey (CLHLS) 8,993 1998 Pres X X X Costa Rican Longevity and Healthy Aging Study (CRELES) 2,827 2004 Pres X X X X The Cross National Equivalent Files (CNEF) 12,900-45,000+ 1970 2010 X X X X Cross-Sectional and Longitudinal Aging Study 2,891 1989 1992 X X Early Indicators of Later Work Levels, Disease, and Death (EI) 39,338 1850 1930 X X X 243 continued
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TABLE 9-1 Continued 244 STUDY FEATURES Biospecimens Baseline Sample Size Start Year End Year Longitudinal International Minority Oversample(s) Anthropometric Measures DATABASE English Longitudinal Study of Ageing (ELSA) 12,100 2000 Pres X X X X Epidemiology of Chronic Disease in the Oldest Old 1970-1979: 2,877 1970 1988 X X 1980-1988: 3,113 Established Populations for Epidemiologic Studies of the Elderly (EPESE) 14,458 1981 1993 X X X German Socio-Economic Panel (GSOEP)—see also Cross National 20,000+ 1984 2011 X X E quivalent Files (CNEF) above Health and Retirement Study (HRS) 22,000+ 1992 Pres X X X X Health Conditions of Elderly Puerto Ricans (PREHCO) 5,336 2000 2006 X X X X Human Mortality Database 37 countries 1751 Pres X X Indonesian Family Life Survey (IFLS) 22,000-44,000 1993 2008 X X X X International Database (IDB) 226 countries 1950 Pres X Iowa 65+ Rural Health Study 3,673 1991 2001 X X X Japanese Study on Aging and Retirement (JSTAR) 4,200 2007 X Irish Longitudinal Study on Ageing (TILDA) 8,000+ 2009 Pres X X X X X Korean Longitudinal Study of Aging (KLoSA) 10,000+ 2006 Pres X X Longitudinal Aging Study in India (LASI) 1,500+ 2010 Pres X X X X Longitudinal Employer-Household Dynamics (LEHD) 48 states or U.S. 1991 Pres X territories
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Longitudinal Studies of Aging (LSOAs) 1984-1990: 7,541 1984 2000 X 1994-2000: 9,447 Longitudinal Study of Generations 300+ three-generation 1971 2001 X families, 2,000+ individuals Longitudinal Study of Mexican-American Elderly Health 3,050 1993 2006 X X X (The Hispanic EPESE) Los Angeles Family and Neighborhood Survey (L.A.FANS) 2,548 2000 2008 X X X X The Luxembourg Income Study (LIS) 30 countries 1968 Pres X Matlab Health and Socioeconomic Survey (MHSS) Main survey: 1996 Pres X 4,364 households Mexican Family Life Survey (MxFLS) 35,000+ 2002 2013 X X X X Mexican Health and Aging Study 15,186 2001 Pres X X X X Midlife Development in Japan (MIDJA) 1,027 2008 Pres X X X X X Midlife Development in the United States (MIDUS) 1995-1996: 7,108 1995 Pres X X X X 2004-2006: 5,555 National Archive of Computerized Data on Aging (NACDA) National Health and Aging Trends Study (NHATS) 8,000+ 2011 Pres X X X National Long Term Care Survey (NLTCS) 20,485 1982 2004 X X X National Longitudinal Mortality Study (NLMS) ~3.3M 1973 2010 X National Longitudinal Survey: 1990 Resurvey of Older Males (NLS-Older 5,020 1966 1990 X X Males) National Nursing Home Survey Follow-up (NNHSF) 6,001 1984 1990 X National Social Life, Health, and Aging Project (NSHAP) 3,004 2005 Pres X X X X The National Survey of Families and Households (NSFH) Reinterview 13,017 2001 2003 X X National Survey of Self-Care and Aging: Baseline and Follow-up 3,485 1990 1994 X 245 The National Survey of the Japanese Elderly (NSJE) 3,990 1987 1993 X X continued
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TABLE 9-1 Continued 246 STUDY FEATURES Baseline Sample Size Start Year End Year Longitudinal International Minority Oversample(s) Anthropometric Measures Biospecimens DATABASE New Beneficiary Survey (NBS) and New Beneficiary Follow-up (NBF) 16,692 1982 1991 X New Immigrant Survey (NIS) 13,981 2003 2004 X X Nihon University Japanese Longitudinal Study of Aging (NUJLSOA) 4,997 1999 2003 X X Panel Study of Income Dynamics (PSID) 65,000+ 1968 Pres X X PHSE Ten-Year Follow-up of the North Carolina EPESE 4,162 1996 1997 X X Precursors of Premature Disease and Death 1,337 1946 2003 X Project TALENT 440,000 1960 X X X 1990 Public Use Microdata Sample for the Older Population (PUMS-O) Unknown 1990 2000 Puerto Rican Elderly Health Conditions 4,291 2002 2007 X X X X RAND Metadata Repository Religion, Aging, and Health Survey 1,500 2001 2004 X X Resources for Enhancing Alzheimer’s Caregiver Health (REACH) REACH: 600 1996 2004 X X and REACH II REACH II: 642 Sacramento Area Latino Study on Aging (SALSA) 1,789 1996 Pres X X X X Seattle Longitudinal Study (SLS) of Adult Cognitive Development 6,000+ 1956 Pres X X The Second Malaysian Family Life Survey (MFLS-2) Senior sample: 1,357 1988 1989 X Social Environment and Biomarkers of Aging Study (SEBAS) in Taiwan 1,023 1999 2006 X X X X Study of Dementia in Swedish Twins 3,838 1990 1999 X X X Study on Global Ageing and Adult Health (SAGE) 90,000+ 2002 Pres X X X X
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Survey of Health, Ageing and Retirement in Europe (SHARE) 31,115 2004 Pres X X X Survey of Health, Ageing and Retirement in Israel (SHARE-Israel) 2,598 2005 Pres X X X Swedish Adoption/Twin Study of Aging (SATSA) 2,020 1984 2005 X X X X Terman Life-Cycle Study, as supplemented 1,528 1922 2000 X The Wechsler Adult Intelligence Scale Archives (NIA-WAIS) on Aging and 50,000+ 1980 1998 X Multiple Cognitive Abilities Whitehall II Study (also known as Stress and Health Study) 10,308 1985 Pres X X X X Wisconsin Longitudinal Study (WLS) (graduates) 10,317 1957 Pres X X X Wisconsin Longitudinal Study (WLS) (siblings) 4,778 1975 Pres X X X The Women’s Health and Aging Study (WHAS I, WHAS II, WHAS III) 1,002; 436; 1,438 1992 Pres X X X DATA SETS TO BE ARCHIVED IN THE FUTURE NIA Collaborative Studies on Dementia Special Care Units (SCUs) 3,000 Nursing 1991 1996 X Homes 1,500 SCUs Origins of Variance in the Old-Old: Octogenarian Twins 351 Same-Sex 1997 2005 X X X (The OCTO Twin Study) Twin Pairs Victoria Longitudinal Study 1,594 1987 Pres X X X X DATA SETS AVAILABLE THROUGH PRINCIPAL INVESTIGATOR Epidemiology of Aging and Physical Functioning 2,092 1993 2006 X X The Longitudinal Study of Aging Danish Twins 4,371 1995 2005 X X X X Maine-Syracuse Longitudinal Study ~2,400 1975 Pres X X X The UAB Study of Aging: Mobility Among Older African-Americans and 1,000 1999 2008 X X X Whites The UNC Alumni Heart Study 6,340 1986 Pres X Vietnam Era Twin Study of Aging (VETSA) 1,006 2002 Pres X X X SOURCE: National Institute on Aging (2012). 247
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248 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE working with partners in other countries to coordinate the collection of comparable cross-national data to understand the epidemiology of health and aging (see Box 9-1). The National Institute of Child Health and Human Development (also part of NIH) and the National Science Foundation fund the University of Minnesota to maintain the Integrated Public Use Micro- data Series-International (IPUMS-International), an effort to inventory, pre- serve, harmonize, and disseminate census microdata from around the world BOX 9-1 International Health Studies of the Population Age 50 and Older International surveys of the population age 50 and older serve as good models of harmonization and collaboration in the production of comparable health information across a number of countries. The United States began this effort with the Health and Retirement Study (HRS) in 1992. HRS, which is administered by the University of Michigan, surveys a representative sample of more than 26,000 Americans over the age of 50 every 2 years. It now has 11 waves of data. It is supported by the National Institute on Aging and the Social Security Administration. The English Longitudinal Study on Ageing (ELSA) began in 2002 with a sample of about 12,000 people age 50 and older and now has had five waves of data collection. The Survey of Health, Ageing and Retirement in Europe (SHARE) is a cross-national panel database with four waves of data for more than 55,000 individuals age 50 or older from 20 European countries. A number of additional countries throughout the world are now undertaking studies that will be part of this family of surveys. These surveys have been developed collaboratively across countries and across disciplines: there is significant overlap in the memberships of their monitoring committees and advisory groups and active investi- gators. Producing comparable international data has been an aim since their beginning. The multidisciplinary approach allows comparable cross- national examination across a wide variety of health outcomes, as well as comparison of the strength of associations with causal or related variables. All of these studies have collected information on health con- ditions, disability, physical functioning, cognitive functioning, risk factors, and health care use and expenditures. They also collect extensive socio- economic, demographic, and life-style factors, as well as information on earlier life events. All three surveys measure functional status, and HRS and ELSA collect biomarkers. SHARE is now piloting biomarker collection.
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RESEARCH AGENDA 249 (University of Minnesota, 2012b).1 The project includes the Integrated Health Interview Series, which compiles a harmonized set of microdata and documentation based on material originally included in the public-use files of the National Health Interview Survey (University of Minnesota, 2012a). Despite these impressive efforts, many of the data we sought for this report were scattered across disparate and sometimes obscure sources, and the data often did not exist, were inconsistently defined, or were contradic- tory. These limitations were often too great to allow us to reach definitive conclusions. We considered what steps the scientific community should take so that future analysts might benefit from a more robust body of evi- dence. Much of what can be done is beyond the scope of a single chapter to catalogue, but we offer three recommendations, beginning with one on the need for better data. DATA NEEDS RECOMMENDATION 1: Acting on behalf of all relevant data-gather- ing agencies in the U.S. Department of Health and Human Services, the National Institutes of Health and the National Center for Health Sta- tistics should join with an international partner (such as the OECD or the World Health Organization) to improve the quality and consistency of data sources available for cross-national comparisons. The partners should establish a data harmonization working group to standard- ize indicators and data collection methodologies. This harmonization work should explore opportunities for relevant U.S. federal agencies to add questions to ongoing longitudinal studies and population surveys that include various age groups—especially children and adolescents— and to replicate validated questionnaire items already in use by other high-income countries. A fundamental challenge to understanding the U.S. health disadvantage is a lack of data to identify, monitor, and analyze epidemiological changes over time. Ambiguities in how best to define and measure health outcomes and determinants of health and inconsistent measurements across countries plague any effort to compare countries on meaningful terms. In some cases, the epidemiological literature has not even confirmed a causal link between 1 The database currently includes approximately 397 million people, from 185 censuses taken in 62 countries from 1960 to the present.
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250 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE some putative causes and associated health outcomes.2 Questions that have been validated in one country may perform differently in other countries, where life-styles, culture, or different meanings in translation can affect the results. Across topic areas, some countries participate in population surveys while others do not. These heterogeneities are an impediment to many efforts to make valid comparisons of health outcomes, determi- nants of health, and relevant contextual factors between one country and another. Thus, our first recommendation focuses on the need for better data, with an emphasis on the health outcomes discussed in this report, and on the determinants of health we reviewed, including health systems, personal behaviors, social and demographic factors, and physical and social environments. Health Outcomes Vital Statistics Although vital statistics are available for nearly all of the popula- tions of high-income countries and arguably measure the most precise endpoints imaginable—birth and death—attributions of cause of death still have inherent imprecision. For example, infant mortality comparisons are affected by differences in how countries register premature births and whether they are reported as live births. Cause-of-death attributions also may vary by country (e.g., “drug-related” deaths and suicides). Physical Illnesses Existing indicators do not go far enough to make meaningful cross- national comparisons of disease profiles of countries. For example, 30-day case-fatality rates assembled by the OECD focus on cross-national com- parisons for only two conditions, acute myocardial infarction and stroke (OECD, 2011b). Similar data are needed for other major causes of death, and follow-up beyond 30 days is important to evaluate the quality of ambulatory and chronic illness care and readmission rates. Internationally comparable data are needed on the prevalence of ambulatory-sensitive conditions beyond the current focus on asthma and diabetes. 2 Examples include precise quantification of the role of diet in causing cardiovascular dis- ease, cancer, and other conditions; disentangling the effects of physical activity independent of obesity and diet; and which forms of “problem drinking” are predictive of disease or injury. Questions also surround the relative contribution of medical care to health outcomes and the causal role of stress, population-based services, and levels of public spending.
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RESEARCH AGENDA 251 Mental Illnesses As discussed in Chapter 2, deficiencies in available data and inconsis- tencies in diagnostic classifications prevented the panel from reaching con- clusions about whether mental illness is more common in the United States than in other peer countries. Continued efforts are needed to standardize the collection of epidemiological data on mental illness based on established diagnostic instruments (see Chapter 2). An accepted international standard is lacking not only for established mental illnesses such as clinical depres- sion, but also for relevant psychological factors, such as stress. Determinants of Health Health Systems Cross-national comparisons of health system performance have been widely attempted (Davis et al., 2010), but they remain rudimentary. Vali- dated indicators exist for delivery of specific services, such as those used for performance measures, but not for other dimensions of care important to outcomes, including measurements of the quality of care coordination for chronic illnesses or the quality of communication between providers and with patients. As discussed in Chapter 4, the only currently available sys- tematic data to compare the quality of health care in countries come from surveys administered by the Commonwealth Fund, which are fielded in only 7-11 countries and rely on the perceptions of patients and primary care pro- viders. Differences in cultural norms and expectations may skew patients’ responses to questions about whether doctors “spend enough time,” make mistakes, or communicate well. Developing more objective measures of quality, coordination, and communication that can be administered con- sistently across countries and can also account for contextual factors (e.g., differences in health systems and social policy) will require a collaborative effort among health services researchers from high-income countries. For medical and public health systems among countries, no established (let alone validated) measures for access or quality are in use, apart from efforts to define the core content of public health, such as the core func- tions or the accreditation criteria recently developed in the United States by the Public Health Accreditation Board (Institute of Medicine, 2012) (see Chapter 4). Even national spending in these areas is difficult to compare: countries differ in both how they track spending on public health or social programs and how they classify these spending categories.3 Community- 3 Forexample, countries differ in what is classified as public health, prevention, health pro- motion, primary care, and social transfers.
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262 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE mation in population surveys (e.g., of diet, drinking habits, physical activ- ity, medical errors). Methodological research should explore the use of biomarkers and objective reference standards to establish the validity of self-reported observations, such as the use of pedometers and global posi- tioning system (GPS) data to validate self-reports of physical activity and the use of administrative and medical record data to validate reports of medical errors. Cross-national comparisons treat countries as units of analysis, but from a policy and statistical perspective they are not truly independent because of cross-national ties, such as drug policies enforced by the Euro- pean Union. The important distinctions may be less about geographic national borders than the relevant regions or populations within countries (Hans, 2009). For example, some argue that U.S. states are more appropri- ate units of comparison for cross-national studies because of the large size of the United States and significant state-level disparities in health status and other health-related variables.7 A further nuance for researchers to tease apart in cross-national com- parisons is whether a risk factor, such as poverty or inadequate education, may have different “toxicity” (health implications) depending on the con- textual circumstances in each country. For example, as discussed in Chapter 6, there is some evidence that the absence of a college education may have greater effects on employment and health in the United States than in other countries. ANALYTIC METHODS DEVELOPMENT RECOMMENDATION 2: The National Institutes of Health and other research funding agencies should support the development of more refined analytic methods and study designs for cross-national health research. These methods should include innovative study designs, cre- ative uses of existing data, and novel analytical approaches to better elu- cidate the complex causal pathways that might explain cross-national differences in health. A daunting methodological challenge is how to design studies to understand the causes of the U.S. health disadvantage. Randomized con- trolled trials, which are considered the strongest evidence of effectiveness 7 Similarly, like the United States, comparison countries also experience important health disparities by province or canton. It could be argued that an “apples to apples” comparison with the United States would contrast similar regions or, perhaps more meaningfully, would compare similar populations in each country, along with appropriate adjustments for relevant covariates affecting health.
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RESEARCH AGENDA 263 in much medical research, are hardly the answer for this field (Anderson and McQueen, 2009; Black, 1996; Braveman et al., 2011c; Glasgow et al., 2006; McQueen, 2009; Petticrew and Roberts, 2003; Victora et al., 2004). Innovations in study designs require thoughtful methodological research and support from funding agencies to sponsor such efforts. The National Institutes of Health, other grant-making institutions, and public-private partnerships could play important roles in funding pilot studies and innova- tive methodological research to develop such designs in collaboration with colleagues in other countries. Recent advances in analytic techniques enable researchers to answer more complex questions about the explanation of between-country dif- ferences in levels and trends of health indicators. These advances include techniques that allow improved causal inferences regarding population differences, such as multilevel analysis methods that account for factors at different levels of organization (e.g., countries, regions, and individuals) (see Diez Roux, 2011); instrumental variable and other approaches that improve causal inferences regarding population-level differences (see Ahern et al., 2009; Hernán and Robins, 2006); and systems modeling tools that allow one to integrate information from different sources and consider dynamic relations. Counterfactual analysis techniques (such as techniques based on population attributable fractions, which allow an assessment of the contribution of specific risk factors to variations in health outcomes between populations [Northridge, 1995]), fixed effects models, complex systems theory (Diez Roux, 2011), and econometric techniques are among the important tools available. In lieu of longitudinal studies, data fusion through statistical matching has been explored as a way of combining data for life-course research (D’Orazio et al., 2006; Rässler, 2002). Longitudinal Research Much of the evidence presented in this report consists of cross-sectional comparisons of mortality and prevalence rates in recent years, along with some historical trend data that span several decades for some indicators. The more important question in understanding the U.S. health disadvan- tage is to explore the relationship between antecedent factors and health outcomes, some of which occur relatively soon after a risk exposure (e.g., unintended pregnancies) and some of which transpire over years or decades. The life-course perspective embraced by this panel places a premium on understanding how the health problems experienced by Americans are shaped by their early life circumstances—and perhaps even the circum- stances of their parents before they were born—and this approach obvi- ously necessitates either prospective longitudinal studies or creative uses of historical data to retrospectively examine causal factors. Clues to the health
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264 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE disadvantages experienced by today’s senior citizens may lie in (archived) post–World War II data on living conditions generations ago. Data to track all age groups are important, but longitudinal data that includes middle- aged adults appear to be especially lacking. The United States is responsible for important longitudinal research, both historically (e.g., the Framingham Heart Study) and in ongoing stud- ies. One example is the National Children’s Study (Hirschfeld et al., 2010), an effort to study the long-term experience of 100,000 children and their families that exemplifies such a commitment but has faced its own chal- lenges. Other examples include the Panel Study of Income Dynamics, the longest running longitudinal household survey in the world (Institute for Social Research, 2011), and the National Longitudinal Surveys (U.S. Bureau of Labor Statistics, 2012). However, the United States generally lags behind the investments other countries have made in conducting longitudinal research. Sweden has main- tained an impressive longitudinal data set for more than a century. The Whitehall Studies in the United Kingdom, which began in the late 1960s, produced seminal data on the role of social determinants of health (Marmot et al., 1991). In New Zealand, the Dunedin Multidisciplinary Health and Development Study has been following 1,037 individuals for four decades, since their birth in 1972-1973. Other classic British cohort studies include the National Study of Health and Development (launched in 1946), the National Child Development Study (launched in 1958), and the British Cohort Study (launched in 1970). Worldwide interest in identifying and measuring early life precursors of both health and socioeconomic outcomes has spawned the launch of “Millennium Cohort Studies” in many countries. These studies include the Danish National British Cohort (100,418 pregnant women, launched in 1996), the Norwegian Mother and Child Cohort (108,000 pregnant women, launched in 1999), the Dutch Generation R Study (9,748 preg- nant women, launched in 2001), Born in Bradford, UK (14,000 pregnant women, launched in 2007), Growing Up in Australia (10,000 children, launched in 2004), Millennium Cohort Study U.K. (20,000 children, launched in 2001), the Étude Longitudinale Français Depuis L’Enfance (20,000 children across France, launched in 2011), and Growing Up in Scotland (8,000 children, launched in 2003, with a second wave of 8,000 children enrolled in 2008).8 The United States has opportunities to expand this genre of research by collecting prospective data on the influence of social factors on health 8 The U.S. Department of Defense also launched a Millennium Cohort Study in 2001, which now involves approximately 150,000 participants, but its focus is on the long-term effects of military deployment.
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RESEARCH AGENDA 265 outcomes. For example, for many years the research community has advo- cated the collection of longitudinal data by NHANES. Another option is to expand the Early Childhood Longitudinal Study (ECLS) by col- lecting data on health outcomes. The ECLS-K of 1998-1999 followed a nationally representative sample of more than 21,000 children who were kindergartners in 1998-1999 through the eighth grade. The ECLS-K pro- gram provides national data on children’s transition to school and their experiences and growth through the eighth grade. The ECLS program also provides data to analyze the relationships among a wide range of family, school, community, and child characteristics with children’s development, learning, and performance in school (National Center for Education Sta- tistics, 2012a). Mining Currently Available Data Although a new wave of long-term longitudinal research is certainly needed, more can be done with the available data already in existence. At a time of limited resources for new research, funding agencies can achieve important economies by funding investigator-initiated studies that propose secondary analysis of existing data sets. For example, BRFSS data could be more effectively mined to uncover more valuable information than cur- rently occurs. Important insights could be obtained by examining historical data because the U.S. health disadvantage has been growing over time and the important antecedents occurred decades ago. An important avenue the panel identified, which it did not have time to explore, would be to map historical trends in social factors, such as poverty and social capital, from post–World War II and to track their evolution over time as the U.S. health disadvantage has grown more pronounced. In some cases, useful data for international comparisons may exist in disparate databases that are familiar only to specialists in certain disci- plines. This report demonstrates the broad spectrum of disciplines relevant to understanding the U.S. health disadvantage, spanning health, social science, economics, and the environment. Even in the digital information era, an exhaustive search of all databases that provide a basis for making international comparisons is challenging. For example, this panel was not confident that it had adequately identified all possible data sources for comparing the physical and social environments in high-income countries. It is possible, for example, that specialists in air quality, climate, social networks, or other disciplines are aware of differences between the United States and other countries that we did not discover in our review. Other opportunities exist in exploiting linked data sets, such as the National Death Index, which combines death records and survey data (Centers for Disease Control and Prevention, 2009c), and in conducting
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266 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE secondary data analysis across multiple studies. For example, the Emerging Risk Factors Collaboration has established a central database on more than 2 million people from more than 125 prospective population-based studies (Emerging Risk Factors Collaboration, 2012). That collaboration’s focus is on risk factors for cardiovascular disease, but a similar model could be pursued to stratify the data by country in order to study determinants of a broader array of cross-national health differences. Another opportunity exists in reinvigorating successful surveys that have not been fielded for many years and could be updated. For example, the most recent European data from HBSC survey are from 2005-2006 (Roberts et al., 2009). Data from that survey on children’s activity lev- els may not reflect current behaviors in an era in which use of electronic devices, video games, and smart phones has probably supplanted many outdoor play activities. In the United States, the National Maternal and Infant Health Survey (NMIHS) has not been conducted since 1988. Other similarly dormant surveys could be revived in a new effort to understand cross-national differences. Discordant family designs are another intriguing model, because they enable statistical comparisons to be made within pairs of twins or clusters of siblings and can help quantify the role of environmental factors in health disparities. This design implicitly controls for confounding from factors that are constant within families and helps to disentangle the different contributions from adult socioeconomic position, childhood socioeconomic position, and genetic factors. Such studies have their limitations, including requirements for large sample sizes, the persistent inability to prove causa- tion or eliminate confounding (e.g., from “ability bias”), random measure- ment error, and international generalizability (Madsen et al., 2010; McGue et al., 2010). However, these study designs remain useful to consider for appropriate research questions. Funding agencies can support efforts by researchers to devise creative strategies to design and conduct such studies and to explore alternative study design concepts that can yield more immediate results. Such efforts have led to important findings. For example, important information about the role of smoking in explaining the U.S. health disadvantage among adults aged 50 and older (see Chapter 6) was derived from sophisticated model- ing studies that relied on evidence based on smoking-attributable fractions (Preston et al., 2010a, 2010b). Further research could explore the validity of this method of estimating contribution to mortality for a variety of con- ditions and age groups.
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RESEARCH AGENDA 267 NEW LINES OF INQUIRY RECOMMENDATION 3: The National Institutes of Health and other research funding agencies should commit to a coordinated portfolio of investigator-initiated and invited research devoted to understanding the factors responsible for the U.S. health disadvantage and potential solutions, including lessons that can be learned from other countries. For reasons noted throughout this report, a meaningful effort to under- stand the U.S. health disadvantage requires multiple lines of inquiry and a long time horizon, which in turn will require ongoing financial and political support. Long-term cohort studies, and even elaborate retrospective stud- ies, require an investment of time and committed funding to sustain data collection over many years. Although financial constraints make long-term commitments to research very difficult, the persistence (and worsening) of the U.S. health disadvantage over decades, with its profound human and economic implications, may justify such an investment. The knowledge gleaned from such research has the potential not only to help the United States regain its footing as a leader in health and improve its long-term eco- nomic outlook but also to broaden universal understanding of the factors responsible for cross-national health differences. The cause-effect relationships for some aspects of the social and other nonmedical determinants of health are not yet well established. Knowing and understanding causal pathways is a first step in devising appropriate policies, but the question of attribution remains. As Deaton (2002, p. 15) argues: “policy cannot be intelligently conducted without an understand- ing of mechanisms; correlations are not enough.”9 A particular suite of questions is especially important in understanding why the United States is experiencing a health disadvantage relative to other countries. We resist the temptation to prioritize the research questions—such as arguing that the study of social determinants is more important than comparing the role of health care systems—because we recognize the fallacy of predicting which lines of scientific inquiry will yield the greatest insights and propel the most important improvements in public health. To fill the gaps in scholarship on the subject, the panel envisions a portfolio of research supported by the National Institutes of Health and other funding entities, including the following: • international tracking studies that maintain a current epidemiologic dashboard on cross-national patterns in the prevalence of diseases, 9 circumstances in which a clear cause-effect relationship cannot be linked with a discrete In policy intervention, there may still be a valid policy argument for pursuing interventions based on other values, with causal mechanisms only partially understood.
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268 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE biomarkers, and risk factors; all-cause and cause-specific mortality rates; and the incidence of injuries for key age groups (especially for people under age 50), by administering the same instrument in a standard group of high-income countries; • further research on how the U.S. health disadvantage is distributed by income and education and what factors may be responsible for the differential influence of income on health; • long-term prospective cohort studies and other innovative designs (e.g., twin and family studies) that could document the role of ante- cedent factors (policy, the environment, social factors, behaviors, and health systems) on the U.S. health disadvantage; • questions about past experiences and exposures (retrospective questions)10 on population surveys, which can facilitate research on life-course influences (although validation of such questions may require longitudinal studies); • retrospective studies of historical data and time-series analyses to better elucidate how past conditions in the United States might help explain current health patterns; • environmental measurement to understand place-based influences on cross-national health disparities, including the effect of land use and urban planning decisions in cities and contextual factors in the large rural areas of the United States;11 and • area-based research using geocodable data, geographic information systems (GIS) technology, and a variety of newer approaches based on global positioning. This report has identified a series of important research questions that deserve exploration, too many to list here. However, it is important to note some of the crucial unanswered research questions about the U.S. health disadvantage: • What specific factors explain the unfavorable birth outcomes (e.g., high infant mortality rates) experienced in the United States, which exist even after adjusting for race, ethnicity, and maternal education? 10 Examples include the National Survey of Family Growth and National Longitudinal Study of Youth. 11 Important areas for future research include characterizing levels and distributions of envi- ronmental risk factors using comparable measures across countries, documenting inequalities in the distribution of these environmental factors, and identifying the extent to which these environmental factors affect health and the extent to which their effects are modulated by individual-, community-, or country-level factors.
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RESEARCH AGENDA 269 • To what extent does inadequate health care explain why Americans are more likely than their counterparts in peer countries to die from: o transportation-related injuries o violence o noncommunicable diseases o communicable diseases • What specific factors explain why the United States has a higher obesity rate than any other high-income country? • Do firearms alone explain the excessively high homicide rate in the United States, including murders of children? • What accounts for the “drug-related” deaths that claim a large proportion of excess years of life lost in the United States? • What specific factors explain why U.S. adolescents have a higher rate of pregnancies and abortions than their counterparts in other high-income countries? • Why does the United States have the highest rate of AIDS among OECD countries? • Is mental illness generally, and are specific mental illnesses, more common in the United States than in other peer countries? • Why are Americans more likely than people elsewhere to describe their health as good or excellent? • Why do Americans have a health advantage for certain condi- tions (e.g., stroke), and can the answers to that phenomenon help explain the causes of health disadvantages for other conditions? • To what extent do social and economic inequality and low social mobility, independent of absolute poverty, contribute to the aggre- gate disadvantage in U.S. health? • To what extent do working conditions in the United States differ from those in peer countries, and how might these contribute to the U.S. health disadvantage? • Are advantaged Americans—by race (e.g., non-Hispanic whites), education, income, insurance status, and risk factors (e.g., non- smokers, nonobese)—in worse health than their counterparts in other countries as some research suggests?12 If true, does the find- 12 Four studies have now reported this pattern (Avendano et al., 2009, 2010; Banks et al., 2006; Martinson et al., 2011a), but some of them looked only at education and not other variables (Avendano et al., 2010), or are restricted to comparisons of a narrow age group in only two countries (Banks et al., 2006). Replication with more focused criteria would help confirm the finding.
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270 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE ing apply to only some of the health conditions for which the United States is experiencing a disadvantage?13 • To what extent do epigenetic processes help explain the links between environmental factors and the biological outcomes ob erved in the s U.S. health disadvantage? • To what extent does the United States lack “protective factors” that buffer the effects of adverse factors, from poverty to adolescent pregnancy? Stable Funding Conditions that encourage investigators to commit themselves to long- term lines of inquiry require confidence in a stable source of funding for competitive applications. Solicitations for proposals that are expected to achieve specific aims within 3-5 years discourage ambitious enterprises, like the National Children’s Study, which follow individuals over their life courses. Another limitation is lack of “ownership” of the problem: no entity in government is responsible for studying the U.S. health disadvantage. Creating an institutional home for such research in the Office of the Director of NIH would give the effort a strategic position to coordinate the research portfolios across the agency’s 27 institutes and centers, to sup- port inclusion of measures from OECD and European studies in relevant NIH-funded studies, and to solicit proposals for developing measures, data collection instruments, and sampling and administration methodologies. Other potential institutional homes include the Office of Global Health at CDC and the U.S. Department of State. Academic centers of excellence, such as the CDC prevention centers, or academic institutions with expertise on social determinants of health, could be further expanded with appropri- ate funding to study the underlying causes of the U.S. health disadvantage. CONCLUSIONS Perhaps the largest impediments to furthering research on comparisons of cross-national health are the data collection capacities of countries. Not all countries are positioned, or can afford, to administer large-scale population surveys on an annual basis and to maintain publicly available data repositories for research use by the scientific community. Impedi- ments include limited budgets, pragmatic and bureaucratic constraints, and the absence of international collaborative arrangements. In the United 13 Further research is needed to know whether the higher rates of disease for certain condi- tions in the United States, such as HIV infection, are differentially distributed across social classes.
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RESEARCH AGENDA 271 States, for example, funding for the National Children’s Study has met with numerous challenges (Wadman, 2012). Countries can sometimes field large surveys, but not on a regular basis. Political considerations can also influ- ence research by dictating what gets measured and who decides. Another challenge is the shortage of qualified investigators to conduct such research. Tenuous funding opportunities affect the training pipeline and discourage young investigators from pursuing research careers directed at the issues covered in this report. Dedicated funding for a research port- folio that includes career development awards and support for investigator- initiated studies would help to change this climate, not to mention the motivation to undertake protracted longitudinal studies. Calls for research in this field by NIH, in particular, would be very per- suasive in shifting attitudes in academia, and universities’ promotion and tenure committees might adopt more enlightened policies on scholarship that draw more young faculty into careers focused on these issues. Estab- lishing special emphasis panels and study sections composed of reviewers with appropriate expertise and knowledge of the special methodological challenges in conducting cross-national comparative research (and who consider a wider range of analytic approaches, appropriate to the subject, than randomized controlled trials) would also cultivate career growth in this field. These changes in research culture might then find their way to professional journals and persuade editors to involve reviewers with appro- priate expertise to make judgments about the worthiness of manuscripts for publication. For their part, scientists and researchers who conduct studies of the U.S. health disadvantage—a topic with profound public policy implications— need to enhance their skills in communicating scientific findings to general audiences, to policy makers, and to stakeholders. These audiences do not generally read peer-reviewed journals or attend scientific meetings, and findings need to be presented in understandable formats and venues that are relevant to their decisions. Work by Marmot (e.g., 2010), Cutler (e.g., Meara et al., 2008), McGinnis (e.g., McGinnis et al., 2002), Woolf (e.g., Woolf, 2011), Lantz (e.g., Lantz et al., 2010), Schoeni (e.g., Schoeni et al., 2011), and Kindig (e.g., Kindig et al., 2010) among others, illustrates how to present scientific evidence about population health interventions— including returns on investment—to nonscientific policy audiences and decision makers who shape public policies. The diversity of disciplines needed for studying and understanding the U.S. health disadvantage, ranging from biomedicine to political science, should compel scientists to enthusiastically embrace interdisciplinary col- laborations. Medicine, public health, epidemiology, sociology, demography, behavioral science, economics, marketing, and other diverse disciplines and fields can all contribute to the study of the U.S. health disadvantage,
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272 U.S. HEALTH IN INTERNATIONAL PERSPECTIVE but they will need to work through differences in nomenclature, research traditions, data repositories, top journals, and key scientific meetings. Yet the collaboration of experts with different perspectives and skills produces insights that are greater than the sum of the parts and holds the greatest promise in solving the mysteries of the U.S. health disadvantage.