Disparities in Indigenous Health: A Cross-Country Comparison Between New Zealand and the United States

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1 Disparities in Indigenous Health: A Cross-Country Comparison Between New Zealand and the United States Dale Bramley, MBChB, MPH, FAFPHM, Paul Hebert, PhD, Leah Tuzzio, MPH, and Mark Chassin, MD, MPP, MPH The indigenous peoples of New Zealand and the United States have much in common. Both have had a history of colonization. In addition, they have become, in numerical terms, minority populations relative to the predominant European and White groups in each country. Maoris (who represent 10% 15% of New Zealand s population) and American Indians/Alaska Natives (who represent 1% 1.5% of the US population) also exhibit substantially poorer health outcomes than the majority populations over a range of health indicators. 1,2 Reducing health disparities has recently become a central focus of health care policies in both countries. In New Zealand, the national health strategy aims to reduce inequalities in health status and to ensure accessible and appropriate services for Maoris, Pacific peoples, and those of low socioeconomic status. 3 In the United States, Healthy People 2010 is the federal government s blueprint for building a healthier nation. 4 It is designed to achieve 2 major overarching goals: increasing Americans quality of life and years of healthy life and ending racial/ethnic disparities in disease burden. Our study s aims were to compare the health status of the indigenous populations of New Zealand and the United States with that of the majority (European/White) populations of these countries over a range of health-related indicators, including health outcomes (i.e., life expectancy, infant mortality, mortality risk ratios), preventive services (i.e., immunization, cervical cancer and breast cancer screening coverage), modifiable risk factors (i.e., smoking, obesity, diabetes), and treatment services (i.e., access to coronary artery bypass grafting, coronary angioplasty, renal transplantation). We discuss gaps in the current availability of health indicator data. The 2 countries differ in regard to the approaches they are taking to reduce the large disparities in the health status of indigenous populations. There are a number of reasons Objectives. We compared the health statuses of the indigenous populations of New Zealand and the United States with those of the numerically dominant populations of these countries. Methods. Health indicators compared included health outcome measures, preventive care measures, modifiable risk factor prevalence, and treatment measures. Results. In the case of nearly every health status indicator assessed, disparities (both absolute and relative) were more pronounced for Maoris than for American Indians/Alaska Natives. Both indigenous populations suffered from disparities across a range of health indicators. However, no disparities were observed for American Indians/Alaska Natives in regard to immunization coverage. Conclusions. Ethnic health disparities appear to be more pronounced in New Zealand than in the United States. These disparities are not necessarily intractable. Although differences in national health sector responses exist, New Zealand may be well placed in the future to evaluate the effectiveness of new strategies to reduce these disparities given the extent and quality of Maori-specific health information available. (Am J Public Health. 2005;95: doi: /ajph ) for these different approaches, including differences in historical understandings of the nature of health disparities, the way in which the health sector is organized, legislative and funding incentives associated with reducing disparities, and the availability of indigenous data to monitor disparities. METHODS We compared health indicators related to the Maori indigenous population of New Zealand and the American Indian/Alaska Native indigenous population of the United States with indicators for the numerically dominant population group in each country: those of European background (or non- Maori/non-Pacific people when European data were unavailable) in New Zealand and non-hispanic Whites in the United States. It should be noted, however, that other minority groups in both countries experience poorer health outcomes than the majority group; examples are Pacific peoples in New Zealand and Hispanic, indigenous Hawaiian, and African American groups in the United States. We selected health indicators on the basis of availability of data, impact on health status, meaningfulness, and susceptibility to influence by the health system. 5 We used the most recent, representative, and comparable data available. Although these data are not always directly comparable between the 2 countries, they do fairly assess the differences that exist within countries in terms of the racial/ethnic groups examined. (Details on the data sources used are available from the first author.) Health Outcome Measures New Zealand data on life expectancy at birth and infant mortality were obtained from the country s Ministry of Health. 6,7 US data for these measures were obtained from the National Center for Health Statistics and the Indian Health Service (IHS), an agency housed within the US Department of Health and Human Services The mortality measures we used in our comparisons were those accounting for the leading causes of death in the 2 countries, 11,12 including lung, bowel, cervical, breast, and prostate cancers; ischemic heart disease; cere- 844 Research and Practice Peer Reviewed Bramley et al.

2 brovascular disease; chronic obstructive pulmonary disease; suicide; diabetes; HIV; and homicide. Mortality data for New Zealand are compiled by the New Zealand Health Information Service, 11 and causes of death are defined according to International Classification of Diseases (ICD; 9th revision) codes. Mortality data for the United States are compiled by the National Center for Health Statistics, 13 which uses codes from the ICD, 10th revision, to identify causes of death. (Details on the ICD codes used in the present analyses are available from the first author.) In the case of both countries, we used crude data to calculate 1999 mortality rates for the indigenous and majority populations by primary cause of death. In addition, we calculated age-adjusted mortality rates using direct standardization 14 and weights based on the 1999 New Zealand population. We also conducted analyses using US-based weights and Segi population-based weights, 11 and these analyses produced results similar to those presented here. In our study, mortality risk ratios refer to the age-adjusted mortality rate in the indigenous population divided by the age-adjusted rate in the majority population. Preventive Care Measures Measles, mumps, rubella, tetanus, pertussis, diphtheria, polio, and hepatitis B immunization data were collected. New Zealand data were derived from the 1996 North Health Survey (the country s most recent immunization survey) 15 ; US data were derived from the country s 2001 National Immunization Survey. 16 Screening coverage data for New Zealand (for 2002 and 2003) were obtained from the Ministry of Health. 17 Breast screening data are presented for women aged 50 to 64 years who had undergone a mammography in the preceding 2 years as part of the country s national breast cancer screening program. Papanicolaou test data are presented for women aged 20 to 69 years who had undergone testing in the preceding 3 years as part of the national cervical cancer screening program. Self-reported data on use of screening services in the United States were obtained from the 1998 National Health Interview Survey. Breast cancer screening data are presented for women 40 years or older who had undergone a mammography in the preceding 2 years. Cervical cancer screening data are reported for women 18 years or older who had undergone a Papanicolaou test in the preceding 3 years. 4 Modifiable Risk Factors Smoking prevalence data for New Zealand (among individuals 15 years or older) were derived from a 2001 tobacco use survey. 18 Smokers were defined as those who smoked either readymade or roll-your-own cigarettes. 18 US smoking data (among individuals 18 years or older) were obtained from the 2001 National Health Interview Survey. 19 Smokers were defined as those who had smoked 100 cigarettes in their lifetime and who now smoked every day or some days. 20 Obesity prevalence data for New Zealand (among those 15 years or older) were obtained from the New Zealand Health Survey. Adult obesity levels were defined as measured body mass indexes (BMIs) of 30 or above among the majority population and 32 or above among Maoris. Overweight levels were defined as BMIs between 25 and 29 among the majority population and between 26 and 31 among Maoris. 21 In the United States, data for White men and women older than 20 years were obtained from the National Health and Nutrition Examination Survey (NHANES). 22 Obesity was defined as a BMI of 30 or above; overweight was defined as a BMI between 25 and 29. The NHANES sampling design does not include American Indians/Alaska Natives living on reservations. Thus, obesity data for American Indians/Alaska Natives were derived from the Strong Heart Survey (data were available for adults aged years). 23 New Zealand diabetes prevalence data (among those 15 years or older) were obtained from the New Zealand Health Survey. Prevalence rates were based on self-reported data. 24 US diabetes prevalence data (among those 20 years or older) were obtained from the Behavioral Risk Factor Surveillance System and from the IHS. 25,26 Treatment Services The rates we present here are relative rates according to racial/ethnic group membership. We did not calculate absolute values, because medical practice characteristics and access to procedures may vary between the 2 countries. In the United States, no national databases exist containing information on treatment procedures (making any comparison of such services difficult). However, the Medicare program maintains administrative data on all US residents older than 65 years. Therefore, these data were deemed to be the most consistent with those available from New Zealand. We made no distinctions regarding whether the use of particular procedures is appropriate or degrees of overuse or underuse that may exist. The New Zealand Ministry of Health supplied treatment service data regarding cardiac procedures. 27 Renal transplant data were derived from the Australia and New Zealand Dialysis and Transplant Registry. 28 US treatment procedure data were derived from published studies involving the Medicare database. 29,30 RESULTS Health Outcome Measures Overall life expectancy was higher in New Zealand (Table 1). Maori males had a life expectancy 8.9 years less than that of non-maori males, whereas Maori females had a life expectancy 9.4 years less than that of non-maori females. In the United States, American Indian/Alaska Native males had a life expectancy 7.4 years less than that of White males, and American Indian/Alaska Native females had a life expectancy 5.8 years less than that of White females. The infant mortality rate was lower in New Zealand (5.4 per 1000 live births) than in the United States (7.2 per 1000 live births). However, the Maori infant mortality rate was higher than the New Zealand European rate, and a similar pattern was seen in the United States in regard to American Indians/Alaska Natives and Whites. New Zealand and US mortality rates are shown in Table 2. Mortality rates (among members of all racial/ethnic groups) from cerebrovascular disease were higher in New Zealand than in the United States, and mortality rates from most cancers were slightly higher. Mortality rates from ischemic heart disease and suicide were similar in the 2 countries. Mortality rates from diabetes, chronic obstructive pulmonary disease, HIV, and homicide were lower in New Zealand. May 2005, Vol 95, No. 5 American Journal of Public Health Bramley et al. Peer Reviewed Research and Practice 845

3 TABLE 1 Health Outcome Measures, by Gender and Ethnicity: United States and New Zealand New Zealand United States Maori/European AIAN/White Difference Maori European Total Difference AIAN White Total Life expectancy a Male Female Infant mortality b Total Note. AIAN = American Indian/Alaska Native. a Life expectancy at birth (years). European life expectancy refers to non-maori population. b Number of deaths in a calendar year among children younger than 1 year per 1000 live births in the same calendar year. In New Zealand, age-adjusted mortality rates were generally higher for Maoris than for those of European backgrounds. With the exception of bowel cancer, risk ratios between Maoris and the majority population were greater than 1 for all causes of death reported. The same was not true for risk ratios between American Indians/Alaska Natives and Whites. American Indians/Alaska Natives exhibited lower age-adjusted death rates than Whites for most causes of death; exceptions were suicide, diabetes, HIV, and homicide. The relationships just described are illustrated in Figure 1; the horizontal axis shows the American Indian/Alaska Native White risk ratio, and the vertical axis shows the Maori/European risk ratio. The vertical and horizontal lines are drawn at a risk ratio of 1.0 (no racial/ethnic difference in mortality risk); the diagonal line is drawn where the US risk ratio equals that of New Zealand (i.e., no difference in racial/ethnic disparities between the countries). It can be seen that most causes of death are above the diagonal line, indicating greater disparities in New Zealand than in the United States. It also can be seen that causes of death tend to be above the horizontal 1.0 risk-ratio line for New Zealand but to the left of the vertical 1.0 risk-ratio line for the United States. Modifiable Risk Factors Maoris exhibited the highest smoking prevalence; 48.6% of Maori adults were smokers, twice the smoking prevalence of the majority population (Table 3). Almost 33% of American Indians/Alaska Natives were smokers, a rate 36% higher than that among White Americans. The highest prevalence of obesity was found among Americans, with 44% and 57% of male and female American Indians/ Alaska Natives, respectively, being obese. The diabetes prevalence was higher in the United States, with American Indians/Alaska Natives exhibiting the highest observed overall prevalence (15.3%). In both countries, the indigenous populations exhibited an almost 3-fold higher diabetes prevalence than the majority populations. Preventive Services In the United States, immunization coverage rates were marginally higher among White American children (Table 3). However, in the case of measles/mumps/rubella, the highest coverage rate observed was that among American Indians/Alaska Natives. New Zealand children exhibited lower immunization rates than US children, and Maori children had the lowest rates. Self-reported breast and cervical cancer screening coverage rates were lower in New Zealand, and again TABLE 2 Age-Adjusted Mortality Rates (per Population) and Mortality Risk Ratios for Major Causes of Death, by Race/Ethnicity: New Zealand and United States, 1999 New Zealand United States Cause of Death Maori European All Races Maori/ European Risk Ratio AIAN White All Races AIAN/White Risk Ratio Malignant neoplasms Malignant neoplasm of trachea, bronchus, and lung Malignant neoplasm of breast Malignant neoplasm of prostate Malignant neoplasm of cervix Malignant neoplasm of colon, rectum, and anus (bowel) Ischemic heart disease Cerebrovascular disease Other chronic obstructive pulmonary disease Suicide (intentional self-harm) Diabetes HIV Homicide (assault) Note. AIAN = American Indian/Alaska Native. 846 Research and Practice Peer Reviewed Bramley et al.

4 Note.NZ=New Zealand; COPD = chronic obstructive pulmonary disease; IHD = ischemic heart disease; CVD = cerebrovascular disease; AIAN = American Indian/Alaska Native. FIGURE 1 Comparison of mortality risk ratios for Maoris versus Europeans in New Zealand and American Indians/Alaska Natives versus Whites in the United States. Maoris exhibited the lowest levels. In New Zealand, the risk ratio for screening coverage (Maori population vs majority) was 0.67 in the case of both breast and cervical cancer. American Indians/Alaska Natives had lower screening coverage rates than Whites. Racial/ ethnic differentials were greater in the United States than in New Zealand for breast cancer screening, but the converse was true for cervical cancer screening. Treatment Services In regard to access to coronary angioplasty, Maoris underwent approximately 50% fewer procedures than those of European backgrounds, while American Indians/Alaska Natives underwent 25% fewer procedures than White Americans (Table 3). Coronary artery bypass grafting rates were similar among Maoris and New Zealand Europeans, but American Indians/Alaska Natives underwent 20% fewer such procedures than White Americans. Among all people aged 15 to 59 years undergoing dialysis in New Zealand in 2001, 3.6% of Maoris went on to receive transplants, compared with 15.5% of the majority population. Among Americans 55 years or younger undergoing dialysis for end-stage renal failure in 1995, 12.1% of American Indians/Alaska Natives went on to receive transplants, compared with 22.7% of White Americans. DISCUSSION In the case of nearly every health indicator we examined, disparities (both absolute and relative) between indigenous and majority populations were more pronounced among Maoris in New Zealand than among American Indians/Alaska Natives in the United States. Relative to the majority populations, both indigenous groups were shown to experience large disparities in health status across most of the indicators assessed, even though, over the past 50 years, these groups have exhibited rapid gains. For example, life expectancy among Maoris increased 27% between 1950 and 1997, from approximately 55 years to 70 years. Recent analyses show that most of this increase took place prior to the mid- 1980s. However, since that period, life expectancy among non-maoris has continued to rise, while that among Maoris has been mostly static, thus producing a widening in disparities. 1 In the United States, life expectancy for American Indians/Alaska Natives increased by 39% between 1940 and 1995, from 51 years to 71 years. Coinciding with this increase, however, has been a parallel increase in mortality rates associated with chronic diseases. 31 To date, relatively few studies have involved comparisons across countries of the health status of indigenous peoples with that of numerically dominant populations Many of the studies available have originated from Australia, and few have included comparisons with New Zealand Maoris. 32,33,35,36 Furthermore, most have reviewed mortality trends only and have not provided wider overviews of health indicators. 32,33,36,37 US Successes in Decreasing Disparities Concerning our findings, of particular interest is the fact that, in the United States, disparities in rates of childhood immunization and cervical cancer screening coverage have largely been eliminated. In the case of immunization, Strine et al. recently noted some of the probable reasons for this success, 39 including comprehensive health services provided through the IHS, integrated primary care services provided in collaboration with tribes (e.g., public health nurse home visits, tracking of immunization status of children, and field clinics held at community centers, schools, and reservations), and free vaccines administered through immunization programs. Community outreach programs also exist to reach remote areas. 39 New Zealand health policymakers could benefit from studying this approach. New Zealand s low immunization coverage levels, compounded by a lack of accurate coverage data, 40 have been a major public health concern for many years. Smoking prevalence disparities are also less pronounced in the United States. Although smoking prevalence is high among American Indians/Alaska Natives (33% of the adult population), it is only 36% higher in relative terms than the prevalence among White Americans, whereas smoking prevalence May 2005, Vol 95, No. 5 American Journal of Public Health Bramley et al. Peer Reviewed Research and Practice 847

5 TABLE 3 Data on Modifiable Risk Ratios (RRs), Preventive Services, and Treatment Services: United States and New Zealand United States New Zealand American Indian/ Outcome Measure RR Maori European RR Alaska Native White Modifiable risk factors Smoking, % Obesity, % Obese Male Female Overweight Male Female Both overweight and obese Male Female Self-reported diabetes, % Preventive service coverage, % Immunization a 3 or more DTP or more polio or more hepatitis B or more MMR Cancer screening Breast Cervical Treatment services Angioplasty b CABG b Transplant c Note. DTP = diphtheria/tetanus/pertussis vaccine; polio = poliovirus vaccine; MMR = measles/mumps/rubella vaccine; angioplasty = coronary angioplasty; CABG = coronary artery bypass grafting; transplant = renal transplantation. a Risk ratios. b Risk ratios. New Zealand: non-risk-adjusted standardized discharge ratios by ethnicity for coronary angioplasty. The European rate is for non-maori/non-pacific peoples. United States: data based on number of persons receiving selected cardiac procedures per 100 Medicare beneficiaries with at least 1 ischemic heart disease hospitalization in c New Zealand: transplant rate among those aged years as a proportion of those undergoing dialysis. United States: percentage of individuals receiving transplants at 1 year of those Medicare end stage renal disease beneficiaries younger than 55 years following renal failure. among Maoris are twice the New Zealand European levels (49% of adult Maoris are current smokers). These findings may partially explain why ischemic heart disease and lung cancer mortality rates among American Indians/Alaska Natives are lower than the corresponding Maori rates. The IHS is likely to have played a significant role in regard to factors that may have contributed to the health gains experienced by American Indians/Alaska Natives. 41 This agency is unique in the United States in delivering health care to a specific ethnic group. Such coordinated mechanisms of health care delivery, if provided adequate resources, could potentially lead to dedicated efforts to reduce health care disparities. The IHS has an annual operating budget of $2.8 billion, contingent on an annual appropriation from Congress and thus susceptible to change. A work group commissioned by the IHS that compared IHS personal health benefits with federal employee health benefit plans estimated that expenditures on IHS services are 46% less than those on federal employee health benefit plans. 42 Despite this apparent underfunding of services, the IHS actively seeks to maximize tribes involvement in meeting the health needs of the registered American Indian/Alaska Native population and to maximize the health care gains available. New Zealand Successes in Decreasing Disparities New Zealand has had particular success in reducing infant mortality rates. From 1950 to 1998, the overall New Zealand infant mortality rate declined from 28 per 1000 births to 6 per More striking has been the decline in the Maori rate over this same period, from 70 to 8 per 1000 births. Recent reductions in the Maori rate are largely due to the drop in deaths caused by sudden infant death syndrome. 43 Infant mortality rates were one of the few health status indicators in which Maoris exhibited better health outcomes than American Indians/ Alaska Natives, although relative indigenous majority disparities were greater for Maoris. Recent data from the New Zealand Ministry of Health suggest that Maoris access to coronary artery bypass grafting has increased. This pattern of improvement is encouraging given that previous studies reported large disparities in access to this procedure. 44 However, it should be noted that, in the present study, rates were not adjusted for severity, incidence, or appropriateness of treatment. The New Zealand Health Services have only recently focused on reducing health care disparities experienced by Maoris. This study demonstrates that disparities are large and that there is considerable room for improvement. However, a number of coordinated strategies are now being put in place, including increasing the number of Maori health care providers and health care workers, increasing funding for regions in which there are high levels of deprivation and large numbers of minority residents, requiring health agencies to produce specific strategies for enhancing the health status of Maoris, and 848 Research and Practice Peer Reviewed Bramley et al.

6 increasing Maoris presence in terms of governance of the health sector. 3,45 47 Data Availability and Methodological Considerations According to the IHS, 2.6 million American Indians/Alaska Natives reside in the United States. Approximately 60% of these individuals are eligible for health services provided by the IHS. 48 Health information on the 40% of American Indians/Alaska Natives not covered by the IHS is largely unavailable. Furthermore, because American Indians/ Alaska Natives represent such a small proportion of the overall American population, health surveys undertaken to gather population prevalence data frequently do not have the statistical power to elicit information related to this group. In New Zealand, such problems have largely been eliminated, in part because Maoris represent a significantly higher proportion of the population and in part because of efforts to increase the size of Maori populations sampled in national health surveys. 21 It should also be noted that, according to the US Bureau of the Census, 4.1 million people identify themselves as American Indians/Alaska Natives in contrast to the figure of 2.6 million just mentioned. 49 The source of this higher figure is the 2000 census; in that year, for the first time, individuals could indicate membership in multiple racial/ethnic groups. Given these differences, there has not been agreement to date as to which population denominator values to use for the American Indian/Alaska Native population. Any change in such denominator values may affect all national health statistics involving American Indians/Alaska Natives (including those described here). Collection of race/ethnicity-specific health information in the United States is also hampered by the lack of national health databases. Furthermore, many health care providers do not collect such data. New Zealand, by comparison, does not experience such difficulties owing to the establishment of national health data sets that include information on race/ethnicity. To measure progress toward reductions in health disparities, it is essential that quality indigenous health data exist, and the United States would benefit from improvements in the collection of these data. In terms of methodological considerations associated with our study, several limitations are inherent in any cross-country comparison of health outcome indicators. Data comparability can be problematic, especially in the case of types of treatment, because guidelines, thresholds for action, and medical practice cultures may vary between countries. However, these potential differences do not have an impact on the relative disparities observed among Maoris and American Indians/Alaska Natives in terms of access to the procedures assessed here. Concerning comparability of mortality data, important issues to consider include differences in ICD coding practices, accuracy of race/ethnicity data within and between countries, and numerator or denominator undercounting among indigenous peoples. In both New Zealand and the United States, studies have shown that there is considerable underreporting of indigenous deaths and other indigenous health indicators Researchers in New Zealand have recently undertaken work designed to better enumerate the magnitude of such problems. 50,51 However, we did not use these data; rather, we used 1999 mortality data, which were outside of the scope of the research just mentioned. Comparable data were also not available for American Indians/Alaska Natives. Another potential limitation of our study is that some of the data relate to national population data sets and some were derived from population samples. In regard to the time periods and age groups for which results are presented, we have attempted to harmonize these data, but there were minor differences. In the case of all of the data collected, the varying degrees to which the indigenous health information that exists for the 2 countries is complete and accurate are likely to have influenced the findings presented here. It is not possible to quantify the exact amount of the measurement bias that may exist. The data presented here, however, are the most reliable currently available. Finally, we have not addressed other factors that may affect the relative size of disparities, particularly differences in socioeconomic status. The importance of socioeconomic variables in influencing health outcomes cannot be underestimated, but it was not our aim to explore such differences. Furthermore, because of the lack of available data and differences between countries in variables such as cost of living, income levels, and definitions of poverty and educational achievement, such a comparison would be methodologically difficult. Conclusions In the case of nearly every health indicator examined here, disparities experienced by Maoris in New Zealand (both absolute and relative to the majority population) were more pronounced than those experienced by American Indians/Alaska Natives in the United States. This situation is not necessarily intractable, as evidenced by the success of the United States in eliminating disparities in immunization coverage among American Indians/Alaska Natives. Although national health sector responses differ, New Zealand may be well placed in the future to evaluate the effectiveness of policies to reduce disparities given the high levels of Maori-specific health information available and the new strategies being put in place. About the Authors At the time of this study, Dale Bramley, Paul Hebert, Leah Tuzzio, and Mark Chassin were with the Department of Health Policy, Mount Sinai Medical School, NY. Requests for reprints should be sent to Dale Bramley, Waitemata District Health Board, DHB Board Office, Level 1, 15 Shea Terrace, Private Bag , Takapuna, Auckland Department of Health Policy, Auckland, New Zealand ( dale.bramley@waitematadhb.govt.nz). This article was accepted May 10, Contributors D. Bramley originated the study; oversaw all aspects of design, analysis, and interpretation; and led the writing of the article. P. Hebert conducted the mortality analysis and assisted with study design and the writing of the article. L. Tuzzio and M. Chassin assisted with design, interpretation, and the writing of the article. Acknowledgments Dale Bramley was on a Harkness Fellowship in health policy for the duration of the present research. Funding for this fellowship was made available by the Commonwealth Fund of New York. We acknowledge the following people who provided advice on or reviews of the article: Rod Jackson (University of Auckland), Nicole Laurie (RAND, Washington, DC), Robin Osborn (Commonwealth Fund, New York), and Dr Anne Beal (Commonwealth Fund). Note. The views presented here are those of the authors and not necessarily those of the Commonwealth Fund. May 2005, Vol 95, No. 5 American Journal of Public Health Bramley et al. Peer Reviewed Research and Practice 849

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