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Kidney disease & Hispanic/Latinos in US..... only 18% of individuals with CKD and 34% of those with eGFRcreat-cyst <60 ml/min per 1.73 m2 were aware of having CKD
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Download the PDF here
Download the PDF here
HCV Extrahepatic
Mortality-kidney/heart/cancers......http://www.natap.org/2014/HCV/060114_05.htm ...... the association between kidney disease & HCV is discussed in several articles within this link, lifestyle related to drug abuse may contribute to the HCV & kidney disease association.
Kidney disease & Hispanic/Latinos in US
Below are the Editorial & the main research article.
Among US Hispanic/Latino adults, there was significant variation in CKD prevalence among Hispanic/Latino background groups, and CKD was associated with established cardiovascular risk factors. The overall prevalence of CKD among Hispanics/Latinos was 13.7%. Among women, the prevalence of CKD was 13.0%, and it was lowest in persons with South American background (7.4%) and highest (16.6%) in persons with Puerto Rican background. In men, the prevalence of CKD was 15.3%, and it was lowest (11.2%) in persons with South American background and highest in those who identified their Hispanic background as "other" (16.0%). The overall prevalence of CKD was similar in HCHS/SOL compared with non-Hispanic whites in NHANES. However, prevalence was higher in HCHS/SOL men and lower in HCHS/SOL women versus NHANES non-Hispanic whites. Low income, diabetes mellitus, hypertension, and cardiovascular disease were each significantly associated with higher risk of CKD.....Our findings of significant variation in the prevalence of CKD between Hispanic/Latino background groups have important public health implications. Prevalence was 17% in women of Puerto Rican background compared with 7% in women of South American background....Although the prevalence of ESRD is higher in Hispanics/Latinos compared with non-Hispanic whites, we found the overall prevalence of CKD to be similar between these two groups. This suggests that Hispanics/Latinos may be at increased risk for CKD progression or alternatively that the mortality rate before the onset of ESRD is higher in non-Hispanic whites compared with Hispanics/Latinos. However, this hypothesis is not supported by analyses of data from NHANES III (16). Future work is needed to better understand .....The ongoing National Institute of Diabetes and Digestive and Kidney Diseases-sponsored Hispanic Chronic Renal Insufficiency Cohort study, which includes Hispanics/Latinos with mild to moderate CKD, is expected to provide additional insights into this issue (17)......we found that the HCHS/SOL participants with CKD were socioeconomically disadvantaged and displayed a high burden of cardiovascular risk factors and other comorbidities. More than one-half had an annual household income <$20,000, 40% lacked medical insurance, 49% had hypertension, 38% had diabetes, and one-half were obese. Furthermore, we found a prevalence of current smoking of 21%, which is concerning given the known association between smoking and adverse CKD outcomes such as progression to ESRD, cardiovascular events, and death (18). Interestingly, mean LDL cholesterol was 120 mg/dl, which is higher than that reported among 2001-2010 NHANES participants with CKD (111 mg/dl) and without CKD (117 mg/dl) (19). Despite the presence of multiple cardiovascular risk factors, only 20% of individuals with CKD were prescribed either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, medications that are known to decrease CKD progression risk (20). Also alarming is our finding that only 18% of individuals with CKD and 34% of those with eGFRcreat-cyst <60 ml/min per 1.73 m2 were aware of having CKD, which is consistent with prior reports (21,22). These findings suggest that there is considerable opportunity to improve CKD management in Hispanics/Latinos, and there is an urgent need to improve CKD awareness among patients who might be missing important preventive and therapeutic opportunities that may decrease their CKD progression risk.
"alarming is our finding that only 18% of individuals with CKD and 34% of those with eGFRcreat-cyst <60 ml/min per 1.73 m2 were aware of having CKD, which is consistent with prior reports.....CKD awareness was reported by 18% of participants who met our study criteria for CKD and by 34% of participants with eGFR <60 ml/min per 1.73 m2 (Table 1)....Of note, the presence of albuminuria was the main determinant of CKD in participants aged 18-44 years, whereas low eGFR was more common among individuals aged 55-74 years......The adjusted prevalence odds for CKD were higher among Hispanics/Latinos with health insurance (OR, 1.25; 95% CI, 1.08 to 1.46), diabetes mellitus (adjusted OR, 1.64; 95% CI, 1.33 to 2.04), hypertension (OR, 1.67; 95% CI, 1.37 to 2.04), and self-reported cardiovascular disease (OR, 1.38; 95% CI, 1.07 to 1.77). "
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Kidney Disease - Hispanic Paradox, Hispanic/Latinos in the US- diet, diabetes, genetics, culture
In summary, we found significant variation in CKD prevalence among Hispanic/Latino background groups. In addition, Hispanics/Latinos with CKD have low rates of health insurance, poor control of hypertension, low angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use, and low awareness of CKD. Correlates of CKD included low income, hypertension, diabetes mellitus, and cardiovascular disease. Our findings have important implications for public health policy targeted at improving access to care and chronic disease management for this rapidly growing population. Future research is needed to better identify modifiable risk factors for CKD progression in Hispanics/Latinos.
We found that the prevalence of CKD, defined as either an eGFRcreat-cyst <60 ml/min per 1.73 m2 or albuminuria was 14%, varied markedly across Hispanic/Latino background groups and was similar to the prevalence of non-Hispanic whites in NHANES. Correlates of CKD included lower annual income, hypertension, diabetes mellitus, and prevalent cardiovascular disease.
According to the 2013 US Renal Data System report, the rate of incident ESRD among Hispanics/Latinos is 50% greater than in non-Hispanics (3).
Our findings of significant variation in the prevalence of CKD between Hispanic/Latino background groups have important public health implications. Prevalence was 17% in women of Puerto Rican background compared with 7% in women of South American background
Although the prevalence of ESRD is higher in Hispanics/Latinos compared with non-Hispanic whites, we found the overall prevalence of CKD to be similar between these two groups. This suggests that Hispanics/Latinos may be at increased risk for CKD progression or alternatively that the mortality rate before the onset of ESRD is higher in non-Hispanic whites compared with Hispanics/Latinos. However, this hypothesis is not supported by analyses of data from NHANES III (16). Future work is needed to better understand risk factors associated with progression of CKD in this population and issues related to the competing risks of death and progression to ESRD.
we found that the HCHS/SOL participants with CKD were socioeconomically disadvantaged and displayed a high burden of cardiovascular risk factors and other comorbidities. More than one-half had an annual household income <$20,000, 40% lacked medical insurance, 49% had hypertension, 38% had diabetes, and one-half were obese. Furthermore, we found a prevalence of current smoking of 21%, which is concerning given the known association between smoking and adverse CKD outcomes such as progression to ESRD, cardiovascular events, and death (18).
Interestingly, mean LDL cholesterol was 120 mg/dl, which is higher than that reported among 2001-2010 NHANES participants with CKD (111 mg/dl) and without CKD (117 mg/dl) (19). Despite the presence of multiple cardiovascular risk factors, only 20% of individuals with CKD were prescribed either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, medications that are known to decrease CKD progression risk (20). Also alarming is our finding that only 18% of individuals with CKD and 34% of those with eGFRcreat-cyst <60 ml/min per 1.73 m2 were aware of having CKD, which is consistent with prior reports (21,22). These findings suggest that there is considerable opportunity to improve CKD management in Hispanics/Latinos, and there is an urgent need to improve CKD awareness among patients who might be missing important preventive and therapeutic opportunities that may decrease their CKD progression risk.
RESULTS
Prevalence of CKD
The overall age-adjusted prevalence of CKD was 13.7% (based on the CKD-EPIcreat-cyst estimating equation). Among women, the overall age-adjusted CKD prevalence was 13.0%; prevalence was lowest in persons with South American background (7.4%) and highest in persons with Puerto Rican background (16.6%) (Table 2). In men, the overall age-adjusted prevalence of CKD was 14.8% and was lowest (11.2%) in persons with South American background and highest (16.0%) in those with other Hispanic background (Table 2). CKD awareness was reported by 18% of participants who met our study criteria for CKD and by 34% of participants with eGFR <60 ml/min per 1.73 m2 (Table 1). Overall, based on the CKD-EPI creatinine GFR estimating equation (cystatin C not available in 2007-2010 NHANES participants), the age-adjusted prevalence of CKD in Hispanics/Latinos from HCHS/SOL was 14.2% (95% CI, 13.4 to 15.0) compared with 13.7% (95% CI, 12.6% to 14.8%) in non-Hispanic whites and 17.4% (95% CI, 15.6 to 19.3) in non-Hispanic blacks from the 2007-2010 NHANES (Figure 1A). Among women, the age-adjusted CKD prevalence in Hispanics/Latinos from HCHS/SOL was 13.6% (95% CI, 12.4 to 14.7) compared with 17.9% (95% CI, 16.2 to 19.5) in non-Hispanic whites and 21.2% (95% CI, 18.0 to 24.4) in non-Hispanic blacks from NHANES (Figure 1B). Among men, the age-adjusted prevalence of CKD in Hispanics/Latinos from HCHS/SOL was 15.2% (95% CI, 14.1 to 16.3) compared with 9.4% (95% CI, 8.2 to 10.7) in non-Hispanic whites and 13.0% (95% CI, 10.8 to 15.1) in non-Hispanic blacks from NHANES (Figure 1C). CKD prevalence stratified by age is presented in Figure 1, D-F. Of note, the presence of albuminuria was the main determinant of CKD in participants aged 18-44 years, whereas low eGFR was more common among individuals aged 55-74 years. Mean serum creatinine, cystatin C, eGFR, and age-unadjusted CKD prevalence, as well as the percentage of the US Hispanic/Latino population by eGFR and albuminuria category using the Kidney Disease Improving Global Outcomes 2009 definition and classification of CKD (9) are presented in Supplemental Tables 1-3.
Baseline Clinical and Demographic Factors Associated with CKD
The adjusted prevalence odds for CKD were higher among Hispanics/Latinos with health insurance (OR, 1.25; 95% CI, 1.08 to 1.46), diabetes mellitus (adjusted OR, 1.64; 95% CI, 1.33 to 2.04), hypertension (OR, 1.67; 95% CI, 1.37 to 2.04), and self-reported cardiovascular disease (OR, 1.38; 95% CI, 1.07 to 1.77). Annual family income >$50,000 was associated with lower odds of CKD (OR, 0.71; 95% CI, 0.54 to 0.94) (Table 3). Hispanic/Latino background group, living in the United States for ≥10 years, educational attainment, and body mass index were not significantly associated with prevalent CKD. Similar patterns were observed separately for low eGFRcreat-cyst and albuminuria (Table 3). In addition, for each 10-year unit increment in age, the odds of low eGFR were nearly 3-fold higher (OR, 2.88; 95% CI, 2.32 to 3.57), US-born Hispanics/Latinos had higher odds of low eGFRcreat-cyst (OR, 2.41; 95% CI, 1.51 to 3.84), and female sex was associated with lower odds of low eGFRcreat-cyst (OR, 0.73; 95% CI, 0.54 to 0.99).
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The Role of Ethnic Variation and CKD - Editorial
Nina T. Harawa and Keith C. Norris
Division of General Internal Medicine and Health Services Research, University of California, Los Angeles, California
Clin J Am Soc Nephrol Oct 2015
""We don't see things as they are, we see them as we are," Anais Nin (author, 1903-1977)."
Advanced CKD is one of the starkest examples of disparities in health conditions, with rates of ESRD for racial/ethnic minorities ranging from 1.5 to 4.0 times those of age-adjusted white counterparts, although there are relatively similar rates for the early stages of CKD (1). Despite the consistent findings of increased ESRD among racial/ethnic minorities, the reasons for these disparities remain elusive. Health research often tries to identify an independent role of race/ethnicity by controlling for factors, such as socioeconomic status, education, health care utilization, and insurance, and exploring potential polymorphisms of genes that may influence the development and/or progression of CKD (1,2). However, rarely do we reflect on what the designation of race/ethnicity actually means beyond a simple census marker. The concepts of race and more recently, ethnicity are deeply integrated into the social fabric of our society. Yet, they often mean different things to different people, and the same person's designation can change or have different implications in different settings. Although both are now self-reported in the census, in most health research, race differs from ethnicity in that, historically, it is a designation imposed on people primarily on the basis of physical characteristics and geographic origin (i.e., American, European, Asian, and African) and stems from four major categories proposed by Francis Bernier in 1684 (3). However, soon thereafter, these four race categories were further elaborated into a more socially constructed and hierarchal set of groupings by Carl Linnaeus, the father of modern taxonomy. As outlined in his treatise Systema Naturae, Linnaeus (4) ascribed each racial category select personality traits, skills, and abilities, providing a scientific foundation for racism (5). The basic categories, however, differ little from the major race groups designated by the US Office of Management and Budget (OMB) (6).
In health research, we commonly use the OMB racial/ethnic designations to categorize individuals and conduct analyses to understand how race and/or ethnicity influence health. Similar but somewhat distinct from race, ethnicity is defined by the OMB with only two major categories (Hispanic/non-Hispanic), with Hispanic referring to people who identify their or their ancestors' heritage, nationality, lineage, or country of birth before arriving in the United States as Hispanic, Latino, or Spanish, regardless of race (6). Of course, the anthropologic and commonplace understandings of ethnicity involve many more categories and ways of categorizing; yet, how best to define and measure the ways that ethnic factors function socially in the United States remains underexamined in the health literature.
Most social science definitions of ethnicity describe what might be referred to as an attributional dimension, describing the sociocultural characteristics (e.g., shared culture and way of life, diet, folkways, and religion) of groups, but ethnicity is a much more complex social construct that influences personal identity and group social relations. Thus, Ford and Harawa (7) have conceptualized a second relational dimension that indexes a group's location within a social hierarchy (e.g., minority versus majority status). This approach can be especially helpful for health researchers aiming to understand how social stratification and social exposures (i.e., risk factors such as discrimination that derive from the social context) contribute to ethnic health inequities (7).
The institutionalized classification of populations using racial/ethnic designations, especially in health, has occurred with little awareness that race and ethnicity do not represent biologic divisions (2). Hence, identifying variation within racial/ethnic groups and describing the specific relational aspects of the ethnic subgroups being compared help to delineate our understanding of human variation but further highlight the problematic foundation of racial classifications themselves. In other words, research, such as that by Ricardo et al. (8) in this issue of the Clinical Journal of the American Society of Nephrology, highlights the ways in which the variation within broad ethnic groups can be as large or larger than that observed between groups.
Although compared with non-Hispanic whites, Hispanics/Latinos in the United States experience lower socioeconomic status and higher rates of health uninsurance/underinsurance, most reports note that they experience greater longevity. Commonly referred to as the Hispanic Paradox (9), this seeming incongruence has prompted a desire to better understand the attributes of Hispanic/Latino ethnicity that lead to such resilience. However, it is important to note the disease-specific and ethnic subgroup-specific exceptions to this overall pattern of lower mortality. Understanding this for many Hispanics/Latinos also requires a transnational perspective that takes into account the role of risk factors in the sending and receiving countries of individuals and/or their ancestors (10). Not surprisingly, given Hispanics/Latino's socioeconomic and insurance status and levels of access to health care in the United States, their risk for negative sequelae from many clinical conditions is increased, including for CKD.
The understanding of unique dimensions of ethnicity has prompted additional investigation of its influence on health through the design of specific cohort studies, such as the Hispanic Health and Nutrition Examination Survey (HHANES) (11). However, it has become clear that, despite the insights gained from the HHANES-based analyses, much is to be lost if we classify Hispanics/Latinos only as a single ethnic group, because they vary tremendously in terms of cultural influences according to national origin and level of acculturation. Variations by national origin also may be influenced by genetic ancestry and selection in different environments, circumstances, and patterns of migration to and settlement in the United States (12). To address this issue, the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) cohort was designed to capture Hispanics/Latinos of multiple national origins and varying levels of acculturation (13).
In this issue of the Clinical Journal of the American Society of Nephrology, Ricardo et al. (8) examined the prevalence of CKD defined by a Chronic Kidney Disease Epidemiology Collaboration eGFR (eGFRcreat-cyst) <60 ml/min per 1.73 m2 or albuminuria, among over 15,000 Hispanic/Latinos of Cuban, Dominican, Mexican, Puerto Rican, Central American, and South American backgrounds in the HCHS/SOL-groups whose average length of time in the United States, immigration status, economic status, reasons for migrating, typical migration experience, and racial composition varied widely. Ricardo et al. (8) found an overall prevalence rate of 13.7%, similar to the overall estimated CKD prevalence of 13.6% in the United States as reported in the 2007-2012 National Health and Nutrition Examination Survey (NHANES) (14). The prevalence varied greatly across persons of different Hispanic/Latino backgrounds, reinforcing the role of ethnic diversity on health profiles of different Hispanic/Latino communities and highlighting how such information may be helpful for community specific CKD prevention, early intervention strategies, and public health messaging. Among the different Hispanic/Latino groups within the HCHS/SOL, persons of South American background in particular had a markedly lower prevalence of CKD, whereas persons of Puerto Rican background and Hispanic other had the highest CKD prevalence rates. Interestingly, the HCHS/SOL Hispanic/Latino women had a lower prevalence of CKD than did the men, which is the opposite of what was found in non-Hispanic whites in NHANES (8). The transition from CKD to ESRD was not formally assessed in this study, but is also known to be multifactorial. A comparison of Hispanic/Latino participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic CRIC studies with non-Hispanic CRIC participants found that Hispanics/Latinos with CKD suffered disproportionately from lower socioeconomic status, higher rates of diabetes mellitus, poor BP control, lower rates of treatment with inhibitors of the renin-angiotensin system, and more severe CKD, contributing to their increased likelihood of developing ESRD compared with non-Hispanics (15).
Other than traditional clinical risk factors, place of birth and acculturation may play important roles in the variation of CKD prevalence rates among different Hispanic/Latino groups. In this study, Ricardo et al. (8) found that birth in the United States was associated with a two-fold adjusted risk of eGFRcreat-cyst<60 ml/min per 1.73 m2, suggesting an important likely role for adoption of Western lifestyle or loss of resilience elements that are fortified in countries of origin. Aspects of acculturation and related factors, such as literacy, social support, health infrastructure of the country of origin, differences in retention/loss of cultural practices (diet and social/family structure), and/or migration-related trauma, were not examined but have been reported by Lora et al. (16) to vary between Hispanics/Latinos of different origins in the United States, and they may contribute to differences in CKD prevalence and progression. Also, select genetic predispositions may exist, especially in Hispanics/Latinos of Puerto Rican, Dominican, and other Caribbean parental ancestry with nondiabetic ESRD who were reported to have prevalence rates of two apo L, 1 (APOL1) risk alleles as high as 20% (17). APOL1 is a strong predictor for kidney disease. Given the proposed two-hit hypothesis, where the APOL1 risk alleles express CKD progression in the presence of another inciting condition or event (18), the high rates of CKD risk factors, such as diabetes and poor BP control, could provide the second hit for at-risk Hispanics/Latinos, contributing to their nearly 50% higher incidence rate of ESRD compared with non-Hispanics/Latinos (14). Ethnic differences in or susceptibility to epigenetic changes are potential promising risk markers that will need to be examined in the future (19).
These findings of substantial ethnic differences in CKD prevalence reported by Ricardo et al. (8) are also consistent with the marked variation in Hispanic/Latino dialysis mortality risk. Frankenfeld et al. (20) noted a substantially lower relative 2-year adjusted mortality risk for Mexican Americans (0.79), Cuban Americans (0.79), and Hispanic others (0.81) compared with non-Hispanics, whereas the mortality risk for Puerto Ricans (1.03) was slightly higher. Thus, persons of Puerto Rican background seem to have not only the highest prevalence rates of CKD but also, unlike most other Hispanic/Latino subgroups, an increased risk of mortality on dialysis. Possible reasons for these differences, such as higher rates of APOL1 risk alleles and differential rates of acculturation, will be important to determine. However, it is also important to keep in mind that Puerto Rican Americans and many Caribbean Latinos are more likely than many other Latino groups in the United States to be racially designated as black and therefore, may be more likely to experience specific types of racism.
A better understanding of the role of ethnicity in health can provide important insights into the social and biologic nuances that affect CKD prevalence, progression, and response to treatment. Such information will be critical as we move toward more precise approaches to medicine, which for rare diseases, may stem from the finding a single gene mutation or polymorphism as has been the case with several cancers (21). Complex conditions such as CKD/ESRD, however, will likely require the integration of genomic profiles and other predictive analytic approaches with the broader social, economic, historical, political, ethnic, cultural, and community context within which a given person lives and has lived (22). The report by Ricardo et al. (8) is a reminder to the renal community of our need to better understand the role of ethnicity in health and an important step forward as we explore the best ways to integrate multiple dimensions of persons and communities to improve CKD outcomes (9).
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Prevalence and Correlates of CKD in Hispanics/Latinos in the United States
Clin J Am Soc Nephrol Oct 2015
Ana C. Ricardo, Michael F. Flessner, John H. Eckfeldt, Paul W. Eggers, Nora Franceschini, Alan S. Go, Nathan M. Gotman, Holly J. Kramer, John W. Kusek, Laura R. Loehr, Michal L. Melamed, Carmen A. Peralta, Leopoldo Raij, Sylvia E. Rosas, Gregory A. Talavera, and James P. Lash
Abstract
Background and objectives The prevalence of ESRD among Hispanics/Latinos is 2-fold higher than in non-Hispanic whites. However, little is known about the prevalence of earlier stages of CKD among Hispanics/Latinos. This study estimated the prevalence of CKD in US Hispanics/Latinos.
Design, setting, participants, & measurements This was a cross-sectional study of 15,161 US Hispanic/Latino adults of Cuban, Dominican, Mexican, Puerto Rican, Central American, and South American backgrounds enrolled in the multicenter, prospective, population-based Hispanic Community Health Study/Study of Latinos (HCHS/SOL). In addition, the prevalence of CKD in Hispanics/Latinos was compared with other racial/ethnic groups in the 2007-2010 National Health and Nutrition Examination Survey (NHANES). Prevalent CKD was defined as an eGFR <60 ml/min per 1.73 m2 (estimated with the 2012 Chronic Kidney Disease Epidemiology Collaboration eGFR creatinine-cystatin C equation) or albuminuria based on sex-specific cut points determined at a single point in time.
Results The overall prevalence of CKD among Hispanics/Latinos was 13.7%. Among women, the prevalence of CKD was 13.0%, and it was lowest in persons with South American background (7.4%) and highest (16.6%) in persons with Puerto Rican background. In men, the prevalence of CKD was 15.3%, and it was lowest (11.2%) in persons with South American background and highest in those who identified their Hispanic background as "other" (16.0%). The overall prevalence of CKD was similar in HCHS/SOL compared with non-Hispanic whites in NHANES. However, prevalence was higher in HCHS/SOL men and lower in HCHS/SOL women versus NHANES non-Hispanic whites. Low income, diabetes mellitus, hypertension, and cardiovascular disease were each significantly associated with higher risk of CKD.
Conclusions Among US Hispanic/Latino adults, there was significant variation in CKD prevalence among Hispanic/Latino background groups, and CKD was associated with established cardiovascular risk factors.
Introduction
Hispanics/Latinos are the largest minority group in the United States and this population is projected to become one-third of the US population by 2060 (1). In addition, Hispanics/Latinos are culturally, socioeconomically, and genetically heterogeneous and represent a wide variety of national origins (2). CKD is a major health problem in the United States and recent evidence suggests that Hispanics/Latinos are disproportionately affected. Over 90,000 US Hispanics/Latinos with ESRD were treated by hemodialysis in 2011, and the rate of incident ESRD among Hispanics/Latinos is 50% greater than in non-Hispanics (3). However, little is known about the prevalence of earlier stages of CKD. Estimates of the prevalence of CKD in the United States are principally derived from the National Health and Nutrition Examination Survey (NHANES). Because NHANES studied mainly Mexican Americans (one-half of which were US born), our understanding of differences in CKD prevalence among major Hispanic/Latino background groups is incomplete. We studied the prevalence and risk factors associated with CKD in a group of Hispanic Americans with a broad range of ethnic backgrounds who were enrolled in a community-based cohort representative of the US Hispanic/Latino population.
Materials and Methods
Study Participants
The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a population-based cohort of 16,415 Hispanics/Latinos aged 18-74 years from randomly selected households in four US field centers (Chicago, Illinois; Miami, Florida; Bronx, New York; and San Diego, California) with baseline examination (2008-2011) and yearly telephone follow-up assessment. Participants self-reported their background as Cuban, Dominican, Mexican, Puerto Rican, or Central or South American. The category "other" was used for participants belonging to a group not listed or to more than one group. The sample design and cohort selection were previously described (4,5). Briefly, a stratified two-stage area probability sample of household addresses was selected in each field center. The first sampling stage randomly selected census block groups with stratification based on Hispanic/Latino concentration and proportion of high/low socioeconomic status. The second sampling stage randomly selected households, with stratification, from US Postal Service registries that covered the randomly selected census block groups. Finally, the study oversampled the group aged 45-74 years (n=9714, 59.2%) to facilitate examination of target outcomes. Sampling weights were generated to reflect the probabilities of selection at each stage. Of 39,384 individuals who were screened and selected and who met eligibility criteria, 41.7% were enrolled, representing 16,415 persons from 9872 households. This study adheres to the Declaration of Helsinki and was approved by the institutional review boards at each field center where all participants gave written consent.
Data Collection and Variable Definition
The baseline study examination included clinical measurements, questionnaires, and fasting venous blood and urine specimens. Demographic factors, socioeconomic status, acculturation, cigarette smoking, and medical history were obtained using standard questionnaires. Medication use was ascertained by conducting an inventory of all currently used medications. BPs were defined as the average of the second and third of three repeat seated measurements obtained after a 5-minute rest. Hypertension was defined as systolic BP ≥140 mmHg, diastolic BP ≥90 mmHg, or use of antihypertensive medication. Diabetes mellitus was defined as fasting plasma glucose of ≥126 mg/dl, 2-hour postload glucose levels of ≥200 mg/dl, a hemoglobin A1c level of ≥6.5%, or use of antidiabetes medication. The presence of cardiovascular disease was self-reported. CKD awareness was ascertained by asking the following question: "Has a doctor ever said that you have kidney problems?"
Kidney Function Measurements
Creatinine was measured in serum and urine on a Roche Modular P Chemistry Analyzer using a creatinase enzymatic method (Roche Diagnostics, Indianapolis, IN). Serum creatinine measurements are isotope dilution mass spectrometry traceable. Urine albumin was measured using an immunoturbidimetric method on the ProSpec nephelometric analyzer (Dade Behring GmbH, Marburg, Germany). Serum cystatin C was measured using a turbidimetric method on the Roche Modular P Chemistry Analyzer (Gentian AS, Moss, Norway). We estimated GFR using three different equations, which were developed from pooling of 5352 participants from 13 studies: (1) Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine, (2) CKD-EPI cystatin C, and (3) CKD-EPI creatinine-cystatin C (eGFRcreat-cyst) (6). CKD was defined by either a low eGFR (<60 ml/min per 1.73 m2) or the presence of albuminuria based on spot urine samples using sex-specific cutoffs (urine albumin/creatinine ratio ≥17 mg/g in men and ≥25 mg/g in women) (7).
Statistical Analyses
Summary statistics, prevalence estimates, and odds ratios (ORs) were weighted to adjust for sampling probability and nonresponse as previously described (4,5).
All analyses account for cluster sampling and the use of stratification in sample selection. Low eGFR, albuminuria, and CKD prevalence were computed by sex and for all participants by Hispanic/Latino background with and without adjustment for age. Survey-specific procedures were used to compute 95% confidence intervals (95% CIs) to account for the two-stage sampling design, stratification, and clustering. Comparisons across Hispanic/Latino groups were performed using the overall Wald test. Multivariable survey logistic regression analyses were used to examine associations of sociodemographic and clinical factors with prevalence of low eGFRcreat-cyst, albuminuria, and CKD. ORs with 95% CIs were computed. All statistical tests were two sided at a significance level of 0.05. No adjustments were made for multiple comparisons. All analyses were performed using SAS software (version 9.2; SAS Institute). Additional analyses were conducted to estimate the prevalence of low eGFR (using the CKD-EPI creatinine equation given that cystatin C was not available in 2007-2010 NHANES participants), albuminuria, and CKD among Mexican Americans (n=2007), non-Hispanic whites (n=4507), and non-Hispanic blacks (n=1938) in the 2007-2010 NHANES. We followed recommendations from the National Center for Health Statistics to account for stratification and clustering of the survey design, as well as oversampling of ethnic minorities and elderly persons (8). Age-adjusted estimates were calculated using the mean age of participants in HCHS/SOL and NHANES (the mean age for HCHS/SOL participants and NHANES participants was 41 years).
Results
Of the 16,415 HCHS/SOL participants, 15,161 (92.4%) were included in analyses to estimate prevalence of low eGFR, albuminuria, and CKD (9032 women and 6129 men); 1001 participants (6.1%) were excluded because of missing data on serum creatinine (n=168), serum cystatin C (n=116), or urine albumin (n=717), and 253 participants were excluded due to missing data regarding race or Hispanic/Latino background group. In addition, 1114 participants were excluded from regression analyses as a result of missing covariate data. Compared with individuals included in the study, those excluded due to missing data were of similar age (mean 41 years), sex (women: 49.9% versus 52.5%, P=0.12), and Hispanic/Latino background. The prevalence of CKD and albuminuria was higher among excluded compared with included participants (22.7% versus 13.4% and 16.1% versus 12.1%, respectively, P<0.001 for each comparison).
Participant Characteristics
The mean age was 41 years (Table 1). Compared with persons without CKD, individuals with CKD were more likely to be older (48 versus 40 years, P<0.001), have annual household income <$20,000 (48% versus 41%, P<0.001), attain less than a high school education (39% versus 31%, P<0.001), and have health insurance (60% versus 49%, P<0.001). Participants with CKD were also more likely to be obese (50% versus 38%, P<0.001), to have diabetes (38% versus 11%, P<0.001), and to have BP >140/90 mmHg (30% versus 8%, P<0.001). Participants with low eGFR had significantly more albuminuria.
Prevalence of CKD
The overall age-adjusted prevalence of CKD was 13.7% (based on the CKD-EPIcreat-cyst estimating equation). Among women, the overall age-adjusted CKD prevalence was 13.0%; prevalence was lowest in persons with South American background (7.4%) and highest in persons with Puerto Rican background (16.6%) (Table 2). In men, the overall age-adjusted prevalence of CKD was 14.8% and was lowest (11.2%) in persons with South American background and highest (16.0%) in those with other Hispanic background (Table 2). CKD awareness was reported by 18% of participants who met our study criteria for CKD and by 34% of participants with eGFR <60 ml/min per 1.73 m2 (Table 1). Overall, based on the CKD-EPI creatinine GFR estimating equation (cystatin C not available in 2007-2010 NHANES participants), the age-adjusted prevalence of CKD in Hispanics/Latinos from HCHS/SOL was 14.2% (95% CI, 13.4 to 15.0) compared with 13.7% (95% CI, 12.6% to 14.8%) in non-Hispanic whites and 17.4% (95% CI, 15.6 to 19.3) in non-Hispanic blacks from the 2007-2010 NHANES (Figure 1A). Among women, the age-adjusted CKD prevalence in Hispanics/Latinos from HCHS/SOL was 13.6% (95% CI, 12.4 to 14.7) compared with 17.9% (95% CI, 16.2 to 19.5) in non-Hispanic whites and 21.2% (95% CI, 18.0 to 24.4) in non-Hispanic blacks from NHANES (Figure 1B). Among men, the age-adjusted prevalence of CKD in Hispanics/Latinos from HCHS/SOL was 15.2% (95% CI, 14.1 to 16.3) compared with 9.4% (95% CI, 8.2 to 10.7) in non-Hispanic whites and 13.0% (95% CI, 10.8 to 15.1) in non-Hispanic blacks from NHANES (Figure 1C). CKD prevalence stratified by age is presented in Figure 1, D-F. Of note, the presence of albuminuria was the main determinant of CKD in participants aged 18-44 years, whereas low eGFR was more common among individuals aged 55-74 years. Mean serum creatinine, cystatin C, eGFR, and age-unadjusted CKD prevalence, as well as the percentage of the US Hispanic/Latino population by eGFR and albuminuria category using the Kidney Disease Improving Global Outcomes 2009 definition and classification of CKD (9) are presented in Supplemental Tables 1-3.
Baseline Clinical and Demographic Factors Associated with CKD
The adjusted prevalence odds for CKD were higher among Hispanics/Latinos with health insurance (OR, 1.25; 95% CI, 1.08 to 1.46), diabetes mellitus (adjusted OR, 1.64; 95% CI, 1.33 to 2.04), hypertension (OR, 1.67; 95% CI, 1.37 to 2.04), and self-reported cardiovascular disease (OR, 1.38; 95% CI, 1.07 to 1.77).
Annual family income >$50,000 was associated with lower odds of CKD (OR, 0.71; 95% CI, 0.54 to 0.94) (Table 3). Hispanic/Latino background group, living in the United States for ≥10 years, educational attainment, and body mass index were not significantly associated with prevalent CKD. Similar patterns were observed separately for low eGFRcreat-cyst and albuminuria (Table 3). In addition, for each 10-year unit increment in age, the odds of low eGFR were nearly 3-fold higher (OR, 2.88; 95% CI, 2.32 to 3.57), US-born Hispanics/Latinos had higher odds of low eGFRcreat-cyst (OR, 2.41; 95% CI, 1.51 to 3.84), and female sex was associated with lower odds of low eGFRcreat-cyst (OR, 0.73; 95% CI, 0.54 to 0.99).
Discussion
The burden of CKD in the US population of Hispanics/Latinos remains uncertain, because the most informative prior national estimate included primarily Mexican Americans and was performed about a decade ago (10). Similarly, whether the higher prevalence of ESRD among Hispanics/Latinos is a result of greater prevalence of earlier stages of CKD or more rapid CKD progression (lower competing risk for death before ESRD) also remains unknown. Our study, the first systematic evaluation of the prevalence of CKD in a large diverse contemporary cohort of Hispanics/Latinos, adds important insights into each of these important questions. We found that the prevalence of CKD, defined as either an eGFRcreat-cyst <60 ml/min per 1.73 m2 or albuminuria was 14%, varied markedly across Hispanic/Latino background groups and was similar to the prevalence of non-Hispanic whites in NHANES. Correlates of CKD included lower annual income, hypertension, diabetes mellitus, and prevalent cardiovascular disease.
According to the 2013 US Renal Data System report, the rate of incident ESRD among Hispanics/Latinos is 50% greater than in non-Hispanics (3). This striking disparity in the burden of ESRD in Hispanics/Latinos underscores the importance of understanding the epidemiology of earlier stages of CKD in this population. However, very little is known about the epidemiology of CKD in Hispanics/Latinos before the onset of dialysis (11). By design, NHANES examines predominantly Mexican Americans and therefore does not provide insights into the prevalence of CKD in other Hispanic/Latino background groups.
Our findings of significant variation in the prevalence of CKD between Hispanic/Latino background groups have important public health implications. Prevalence was 17% in women of Puerto Rican background compared with 7% in women of South American background. This is consistent with a prior finding from HCHS/SOL of substantial differences in cardiovascular risk factor burden among Hispanic/Latino background groups (cardiovascular risk factors are also risk factors for CKD) (12,13). After adjusting for clinical and demographic factors, the risk of CKD was similar across all Hispanic/Latino background groups. By contrast, the Hispanic Health and Nutrition Examination Survey reported a higher risk for CKD (defined as estimated creatinine clearance < 60 ml/min per 1.73 m2) in mainland Puerto Ricans and Cuban Americans compared with Mexican Americans (14). However, this survey was conducted >30 years ago and did not include an assessment of urinary albumin or serum cystatin C. Our findings in a larger, contemporaneous, and diverse cohort suggest that differences in CKD prevalence across background groups are explained by modifiable factors, including diabetes mellitus, hypertension, and cardiovascular disease. Nonetheless, future work is needed to explore the importance of additional risk factors, including genetic susceptibility (e.g., the presence of at-risk variants of apolipoprotein L1, which have been associated with increased risk of progression to ESRD in Hispanics with a greater degree of African ancestry) (15).
Although the prevalence of ESRD is higher in Hispanics/Latinos compared with non-Hispanic whites, we found the overall prevalence of CKD to be similar between these two groups. This suggests that Hispanics/Latinos may be at increased risk for CKD progression or alternatively that the mortality rate before the onset of ESRD is higher in non-Hispanic whites compared with Hispanics/Latinos. However, this hypothesis is not supported by analyses of data from NHANES III (16). Future work is needed to better understand risk factors associated with progression of CKD in this population and issues related to the competing risks of death and progression to ESRD. The ongoing National Institute of Diabetes and Digestive and Kidney Diseases-sponsored Hispanic Chronic Renal Insufficiency Cohort study, which includes Hispanics/Latinos with mild to moderate CKD, is expected to provide additional insights into this issue (17).
We also found that the prevalence of CKD was higher in men than women. Furthermore, in multivariable analyses, the odds of eGFRcreat-cyst <60 ml/min per 1.73 m2 were lower in women than men. Interestingly, this is the opposite of what has been found in non-Hispanic whites (10). Reasons for these differences are not clear and need further investigation. It is possible that these contrasting findings may be related to the lack of studies examining the validity of the eGFR equations in Hispanic/Latino background groups. In addition, we found that the HCHS/SOL participants with CKD were socioeconomically disadvantaged and displayed a high burden of cardiovascular risk factors and other comorbidities. More than one-half had an annual household income <$20,000, 40% lacked medical insurance, 49% had hypertension, 38% had diabetes, and one-half were obese. Furthermore, we found a prevalence of current smoking of 21%, which is concerning given the known association between smoking and adverse CKD outcomes such as progression to ESRD, cardiovascular events, and death (18). Interestingly, mean LDL cholesterol was 120 mg/dl, which is higher than that reported among 2001-2010 NHANES participants with CKD (111 mg/dl) and without CKD (117 mg/dl) (19). Despite the presence of multiple cardiovascular risk factors, only 20% of individuals with CKD were prescribed either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, medications that are known to decrease CKD progression risk (20). Also alarming is our finding that only 18% of individuals with CKD and 34% of those with eGFRcreat-cyst <60 ml/min per 1.73 m2 were aware of having CKD, which is consistent with prior reports (21,22). These findings suggest that there is considerable opportunity to improve CKD management in Hispanics/Latinos, and there is an urgent need to improve CKD awareness among patients who might be missing important preventive and therapeutic opportunities that may decrease their CKD progression risk.
To estimate GFR in this study, we used three different equations (creatinine and cystatin C based) that have been validated in large and diverse US populations (6); however, they did not include a significant number of Hispanics/Latinos in the cohorts used to establish them. Despite this shortcoming, the CKD prevalence estimates were similar for each of these equations. Future work is needed to validate GFR estimating equations in Hispanics/Latinos.
Our findings confirmed the strong association of established risk factors (e.g., hypertension and diabetes mellitus) with prevalent CKD in the Hispanic/Latino population. Similar to other studies (23-26), we found that lower annual household income was associated with prevalent CKD. We found a positive association between having health insurance and CKD; the reason for this finding is not clear, but we suspect that this could be because individuals with CKD have comorbid conditions (e.g., hypertension, diabetes mellitus) and therefore may be more likely to seek insurance coverage. We also examined issues related to acculturation, which are particularly relevant to the Hispanic/Latino population. Although place of birth and length of residence in the United States were not associated with increased risk for CKD (defined as albuminuria or eGFRcreat-cyst <60 ml/min per 1.73 m2), birth in the United States was associated with a >2-fold higher adjusted odds of having an eGFRcreat-cyst <60 ml/min per 1.73 m2. This potentially suggests that the Western lifestyle adopted by US-born Hispanics/Latinos may be associated with increased risk for CKD and is consistent with an analysis from NHANES III, which found an association between birth in the United States and heightened cardiovascular risk (27).
Our study has a number of positive features. First, this was a community sample and provides an opportunity to establish population estimates of prevalence. Second, we studied Hispanics/Latinos with diverse backgrounds. Third, the sample size was relatively large and participants were recruited from across the United States. Our findings should be considered with the following limitations. First, the classification of persons with CKD was based on single measurements of serum creatinine, cystatin C, and urine albumin. Second, the GFR estimating equations we used have not been yet validated in Hispanics/Latinos. Third, the cross-sectional study design limits interpretation of these associations. Finally, we used a second, nonconcurrent study, 2007-2010 NHANES, to compare prevalence of CKD in HCHS/SOL participants with non-Hispanics.
In summary, we found significant variation in CKD prevalence among Hispanic/Latino background groups. In addition, Hispanics/Latinos with CKD have low rates of health insurance, poor control of hypertension, low angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use, and low awareness of CKD. Correlates of CKD included low income, hypertension, diabetes mellitus, and cardiovascular disease. Our findings have important implications for public health policy targeted at improving access to care and chronic disease management for this rapidly growing population. Future research is needed to better identify modifiable risk factors for CKD progression in Hispanics/Latinos.
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