Associations of acculturation and kidney dysfunction among Hispanics and Chinese from the Multi-Ethnic Study of Atherosclerosis (MESA)

Racial and Ethnic Differences in All-Cause and Cardiovascular Disease Mortality: The MESA Study

BACKGROUND

Despite improvements in population health, marked racial and ethnic disparities in longevity and cardiovascular disease (CVD) mortality persist. This study aimed to describe risks for all-cause and CVD mortality by race and ethnicity, before and after accounting for socioeconomic status (SES) and other factors, in the MESA study (Multi-Ethnic Study of Atherosclerosis).

METHODS

MESA recruited 6814 US adults, 45 to 84 years of age, free of clinical CVD at baseline, including Black, White, Hispanic, and Chinese individuals (2000-2002). Using Cox proportional hazards modeling with time-updated covariates, we evaluated the association of self-reported race and ethnicity with all-cause and adjudicated CVD mortality, with progressive adjustments for age and sex, SES (neighborhood SES, income, education, and health insurance), lifestyle and psychosocial risk factors, clinical risk factors, and immigration history.

RESULTS

During a median of 15.8 years of follow-up, 22.8% of participants (n=1552) died, of which 5.3% (n=364) died of CVD. After adjusting for age and sex, Black participants had a 34% higher mortality hazard (hazard ratio [HR], 1.34 [95% CI, 1.19-1.51]), Chinese participants had a 21% lower mortality hazard (HR, 0.79 [95% CI, 0.66-0.95]), and there was no mortality difference in Hispanic participants (HR, 0.99 [95% CI, 0.86-1.14]) compared with White participants. After adjusting for SES, the mortality HR for Black participants compared with White participants was reduced (HR, 1.16 [95% CI, 1.01-1.34]) but still statistically significant. With adjustment for SES, the mortality hazards for Chinese and Hispanic participants also decreased in comparison with White participants. After further adjustment for additional risk factors and immigration history, Hispanic participants (HR, 0.77 [95% CI, 0.63-0.94]) had a lower mortality risk than White participants, and hazard ratios for Black participants (HR, 1.08 [95% CI, 0.92-1.26]) and Chinese participants (HR, 0.81 [95% CI, 0.60-1.08]) were not significantly different from those of White participants. Similar trends were seen for CVD mortality, although the age- and sex-adjusted HR for CVD mortality for Black participants compared with White participants was greater than all-cause mortality (HR, 1.72 [95% CI, 1.34-2.21] compared with HR, 1.34 [95% CI, 1.19-1.51]).

CONCLUSIONS

These results highlight persistent racial and ethnic differences in overall and CVD mortality, largely attributable to social determinants of health, and support the need to identify and act on systemic factors that shape differences in health across racial and ethnic groups.

Low Estimated Glomerular Filtration Rate Is Prevalent among North Korean Refugees in South Korea

Background

The number of North Korean refugees entering South Korea is rising. Few studies have investigated the risk of non-communicable disease in North Korean refugees. Moreover, kidney insufficiency, a risk factor for cardiovascular disease, has not been studied in this population. We compared the prevalence of non-communicable disease and kidney function in North Korean refugees and South Koreans.

Methods

Our study was conducted using a case-control design. We enrolled 118 North Korean refugees from the Hana Center and selected 472 randomly sampled South Korean individuals as controls, who were age- and sex-matched with the North Korean refugees in a ratio of 1:4, from the 2014 Korea National Health and Nutrition Examination Survey database.

Results

The prevalence of non-communicable disease did not differ significantly between the groups; however, a low estimated glomerular filtration rate (eGFR; <90 mL/min per 1.73 m²) was more prevalent in the North Korean refugees than in the South Korean population (52.1% vs. 29.9%, P<0.001). After adjusting for covariates and weight gain after escape, the prevalence of a low eGFR was associated with the length of residence in South Korea (odds ratio, 2.84; 95% confidence interval, 1.02–7.89).

Conclusion

The prevalence of non-communicable disease did not differ between North Korean refugees and the South Korean population, while a low eGFR was more prevalent in North Korean refugees than in South Koreans. Moreover, after adjusting for other covariates, the prevalence of a low eGFR in North Korean refugees was associated with the length of residence in South Korea.

CKD and ESRD in US Hispanics

Hispanics are the largest racial/ethnic minority group in the United States, and they experience a substantial burden of kidney disease. Although the prevalence of chronic kidney disease (CKD) is similar or slightly lower in Hispanics than non-Hispanic whites, the age- and sex-adjusted prevalence rate of end-stage renal disease is almost 50% higher in Hispanics compared with non-Hispanic whites. This has been attributed in part to faster CKD progression among Hispanics. Furthermore, Hispanic ethnicity has been associated with a greater prevalence of cardiovascular disease risk factors, including obesity and diabetes, as well as CKD-related complications. Despite their less favorable socioeconomic status, which often leads to limited access to quality health care, and their high comorbid condition burden, the risk for mortality among Hispanics appears to be lower than for non-Hispanic whites. This survival paradox has been attributed to a complex interplay between sociocultural and psychosocial factors, as well as other factors. Future research should focus on evaluating the long-term impact of these factors on patient-centered and clinical outcomes. National policies are needed to improve access to and quality of health care among Hispanics with CKD.

Acculturation and chronic kidney disease in the Hispanic community health study/study of Latinos (HCHS/SOL)

Hispanics/Latinos are burdened by chronic kidney disease (CKD). The role of acculturation in this population has not been explored. We studied the association of acculturation with CKD and cardiovascular risk factor control. We performed cross-sectional analyses of 13,164 U.S. Hispanics/Latinos enrolled in the HCHS/SOL Study between 2008 and 2011. Acculturation was measured using the language and ethnic social relations subscales of the Short Acculturation Scale for Hispanics, and proxies of acculturation (language preference, place of birth and duration of residence in U.S.). CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m² or urine albumin-to-creatinine ratio ≥ 30 mg/g. On multivariable analyses stratified by age, lower language subscale score was associated with higher odds of CKD among those older than 65 (OR 1.29, 95% CI, 1.03, 1.63). No significant association was found between proxies of acculturation and CKD in this age strata. Among individuals aged 18–44, a lower language subscale score was associated with lower eGFR (β = −0.77 ml/min/1.73 m², 95% CI −1.43, −0.10 per 1 SD increase) and a similar pattern was observed for ethnic social relations. Among those older than 65, lower language subscale score was associated with higher log-albuminuria (β = 0.12, 95% CI 0.03, 0.22). Among individuals with CKD, acculturation measures were not associated with control of cardiovascular risk factors. In conclusion, lower language acculturation was associated with a higher prevalence of CKD in individuals older than 65. These findings suggest that older individuals with lower language acculturation represent a high risk group for CKD.

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Among Hispanics/Latinos, lower language acculturation was associated with a higher prevalence of chronic kidney disease in older individuals.

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Based on our findings, older individuals with lower language acculturation represent a high-risk group for chronic kidney disease.

Acculturation and activity behaviors in Chinese American immigrants in New York City

Asian Americans have lower levels of physical activity (PA) compared to other racial/ethnic groups; however, there is little understanding of the social and cultural determinants of PA in this population. Few analyses describe specific PA domains (occupation-, transportation-, recreation-related), focus on one Asian subgroup, or use validated scales. The study objective was to assess the association between acculturation and activity behaviors (meeting 2008 PA guidelines, activity minutes by PA domain, sitting time) in a cross-sectional sample of urban-dwelling, Chinese American immigrants. Data were from the Chinese American Cardiovascular Health Assessment (CHA CHA) 2010-11 among participants with valid reports of PA minutes, assessed by the WHO Global Physical Activity Questionnaire (n = 1772). Acculturation was assessed using the Stephenson Multigroup Acculturation Scale, a 32-item instrument which characterizes two acculturative dimensions: ethnic society (Chinese) immersion and dominant society (American) immersion (maximum possible scores = 4). Multivariable models regressing activity behaviors on acculturation were run, adjusting for age, sex, household income, education, and age at immigration. Ethnic society immersion was high (mean = 3.64) while dominant society immersion was moderate (mean = 2.23). Higher ethnic society immersion was associated with less recreation-related PA (- 40.7 min/week); higher dominant society immersion was associated with a higher odds of meeting PA guidelines (OR: 1.66 (1.25, 2.20), p < 0.001) and more recreation-related PA (+ 36.5 min/week). Given low PA levels in Chinese adults in China, results suggest that PA for leisure may increase and become a more normative behavior among Chinese American immigrants with acculturation. Understanding acculturation level may inform strategies to increase PA in Chinese Americans.

Levels of Acculturation of Chinese Older Adults in the Greater Chicago Area - The Population Study of Chinese Elderly in Chicago

Acculturation is a difficult process for minority older adults for a variety of reasons, including access and exposure to mainstream culture, competing ethnic identities, and linguistic ability and preference. There is a paucity of research regarding overall level of acculturation for Chinese older adults in the United States. This study aimed to provide an overall estimate of level of acculturation of Chinese older adults in the United States and to examine correlations between sociodemographic characteristics, self-reported health measures, and level of acculturation. Data were collected through the Population Study of Chinese Elderly in Chicago (PINE) study. This community-based participatory research study surveyed 3,159 Chinese older adults aged 60 and older. The PINE Study Acculturation Scale was used to assess level of acculturation in three dimensions: language preference, media use, and ethnic social relations. Mean acculturation level for all items was 15.3 ± 5.1, indicating low levels of acculturation. Older age, more offspring, lower income, fewer years living in the United States, lower overall health status, and lower quality of life were associated with lower levels of acculturation. Level of acculturation was low in Chinese older adults, and certain subsets of the population were more likely to have a lower level of acculturation. Future research should investigate causality and effects of level of acculturation.

Hypertension in minority populations: new guidelines and emerging concepts

Persistent disparities in hypertension, CKD, and associated cardiovascular disease have been noted in the United States among racial/ethnic minority groups. Overall, these disparities are largely mediated by social determinants of health. Yet, emerging data suggest additional biologic factors in racial/ethnic disparities in hypertension prevalence, complications, particularly CKD, and responses to treatment. Nevertheless, race is a social construct and not a physiologic concept, and ethnicity, federally defined as the binary "Hispanic/Latino" or "not Hispanic/Latino," is also imprecise. However, race/ethnicity categories may help interpret health-related data, including surveillance and research, and are important in ensuring that clinical trials remain generalizable to diverse populations. There is significant heterogeneity among prespecified groups and, perhaps, greater genetic differences within than between certain racial/ethnic groups. This review will explore hypertension epidemiology, pathophysiology, and management among the diverse and growing US minority groups, specifically African Americans and Hispanics because much less data are available across the wide spectrum of diverse populations. We will highlight the intersection of hypertension and increasingly prevalent CKD, particularly in African Americans. Finally, we propose multidimensional treatment approaches to hypertension among diverse populations, encompassing population, community, health system, and individual-based approaches.

Age at Immigration and Kidney Function among Self-Identified Healthy Africans in the United States

Kidney disease disparately affects those of African descent. Age trends have generally been established for kidney function in the overall US population, but the contribution of age at the time of immigration for African immigrants is unknown. To examine the independent and joint effects of age and age at the time of immigration, and kidney function. Estimated glomerular filtration rate (eGFR) was calculated for 93 African immigrants (60 % male; mean age = 33.5). Hierarchical regression and post hoc analyses revealed a significant age × age at the time of immigration interaction after accounting for traditional risk factors among those who immigrated at age ≤21. Younger age at the time of immigration to the US may exacerbate an inverse relationship between age and kidney function in a self-identified healthy African immigrant sample. Investigation of biopsychosocial factors associated with kidney health among African immigrants is warranted.

Population structure of Hispanics in the United States: the multi-ethnic study of atherosclerosis

Using ∼60,000 SNPs selected for minimal linkage disequilibrium, we perform population structure analysis of 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By projection of principal components (PCs) of ancestry to samples from the HapMap phase III and the Human Genome Diversity Panel (HGDP), we show the first two PCs quantify the Caucasian, African, and Native American origins, while the third and fourth PCs bring out an axis that aligns with known South-to-North geographic location of HGDP Native American samples and further separates MESA Mexican versus Central/South American samples along the same axis. Using k-means clustering computed from the first four PCs, we define four subgroups of the MESA Hispanic cohort that show close agreement with self-identification, labeling the clusters as primarily Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. To demonstrate our recommendations for genetic analysis in the MESA Hispanic cohort, we present pooled and stratified association analysis of triglycerides for selected SNPs in the LPL and TRIB1 gene regions, previously reported in GWAS of triglycerides in Caucasians but as yet unconfirmed in Hispanic populations. We report statistically significant evidence for genetic association in both genes, and we further demonstrate the importance of considering population substructure and genetic heterogeneity in genetic association studies performed in the United States Hispanic population.

Using genotype data from about 60,000 distinct genetic markers, we examined population structure in 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By comparing genetic ancestry of MESA Hispanic participants to reference samples representing worldwide diversity, we show major differences in ancestry of MESA Hispanics reflecting their Caucasian, African, and Native American origins, with finer differences corresponding to North-South geographic origins that separate MESA Mexican versus Central/South American samples. Based on our analysis, we define four subgroups of the MESA Hispanic cohort that show close agreement with the following self-identified regions of origin: Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. We examine association of triglycerides with selected genetic markers, and we further demonstrate the importance of considering differences in genetic ancestry (or factors associated with genetic ancestry) when performing genetic studies of the United States Hispanic population.

Hispanic ethnicity and vascular access use in patients initiating hemodialysis in the United States

BACKGROUND AND OBJECTIVES

Hispanics are the largest minority in the United States (comprising 16.3% of the US population) and have 1.5 times the age-, sex-, and race-adjusted incidence of ESRD compared with non-Hispanics. Poor health care access and low-quality care generally received by Hispanics are well documented. However, little is known regarding dialysis preparation of Hispanic patients with progressive CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using data from Medical Evidence Report form CMS-2728-U3, 321,996 adult patients of white or black race were identified who initiated hemodialysis (HD) between July 1, 2005 and December 31, 2008. The form captures Hispanic ethnicity, vascular access use at first outpatient HD, sociodemographic characteristics, and comorbidities. This study also examined whether use of an arteriovenous fistula (AVF) or graft (AVG) was reported.

RESULTS

AVF/AVG use was reported in 14.5% of Hispanics and 17.6% in non-Hispanics (P<0.001). The unadjusted prevalence ratio (PR) was 0.85 (95% confidence interval [95% CI], 0.83-0.88), indicating that Hispanics were 15% less likely to use AVG/AVF for their first outpatient HD. Adjustment for age, sex, and race, as well as a large number of comorbidities and frailty indicators, did not change this association (PR, 0.85; 95% CI, 0.83-0.88). Further adjustment for timing of first predialysis nephrology care, however, attenuated the PR by two-thirds (PR, 0.94; 95% CI, 0.92-0.97).

CONCLUSIONS

Hispanics are less likely to use arteriovenous access for first outpatient HD compared with non-Hispanics, which seems to be explained by variation in the access to predialysis nephrology care.

Progression of CKD in Hispanics: potential roles of health literacy, acculturation, and social support

Hispanics are the fastest growing minority group in the United States, and compared with non-Hispanic whites, they have a higher incidence of end-stage renal disease. Examining novel factors that may explain this disparity in progression of chronic kidney disease (CKD) in Hispanics is urgently needed. Interpersonal and patient-centered characteristics, including health literacy, acculturation, and social support, have been shown to affect health outcomes in patients with other chronic diseases. However, these characteristics have not been well studied in the context of CKD, particularly in relation to disease knowledge, attitudes, and behaviors. In this report, we examine the potential roles of these factors for CKD progression in Hispanics and propose targeted therapeutic interventions.

Racial and ethnic differences in kidney function decline among persons without chronic kidney disease

Whether the rate of kidney function decline before the onset of CKD differs among racial and ethnic groups remains unclear. Here, we evaluated kidney function decline and incident CKD among white, black, Hispanic, and Chinese participants in the Multi-Ethnic Study of Atherosclerosis (MESA) during 5 years of follow-up. We estimated GFR using both cystatin C (eGFRcys) and creatinine (eGFRcreat). The definition of incident CKD required eGFRcys <60 ml/min per 1.73 m(2) and a decline in eGFRcys ≥1 ml/min per year. Among participants with eGFRcreat >60 ml/min per 1.73 m(2) at baseline, blacks had a significantly higher rate of kidney function decline than whites (0.31 ml/min per 1.73 m(2)/yr faster on average, P=0.001), even after adjusting for multiple potential confounders. Among Hispanics, Dominicans and Puerto Ricans had faster rates of decline than whites (0.55 and 0.47 ml/min per 1.73 m(2)/yr faster, respectively). Mexicans, South Americans, or other Hispanics had similar rates of decline compared to whites. We did not detect significant differences in the rates of kidney function decline among Chinese and white participants. Among those with normal or near-normal kidney function at baseline, blacks and Hispanics had the highest rates of incident CKD during follow-up. Adjustment for comorbidities attenuated some of these differences. In conclusion, the average rate of kidney function decline before the onset of CKD differs among racial and ethnic groups. Traditional risk factors do not explain these differences fully, highlighting the need to explore these disparities.