Kidney disease and the cumulative burden of life course socioeconomic conditions: the Atherosclerosis Risk in Communities (ARIC) study

Individual and neighborhood-level social and deprivation factors impact kidney health in the GLOMMS-CORE study

Prospective cohort studies of kidney equity are limited by a focus on advanced rather than early disease and selective recruitment. Whole population studies frequently rely on area-level measures of deprivation as opposed to individual measures of social disadvantage. Here, we linked kidney health and individual census records in the North of Scotland (Grampian area), 2011-2021 (GLOMMS-CORE) and identified incident kidney presentations at thresholds of estimated glomerular filtration rate (eGFR) under 60 (mild/early), under 45 (moderate), under 30 ml/min/1.73m2 (advanced), and acute kidney disease (AKD). Household and neighborhood socioeconomic measures, living circumstances, and long-term mortality were compared. Case-mix adjusted multivariable logistic regression (living circumstances), and Cox models (mortality) incorporating an interaction between the household and the neighborhood were used. Among census respondents, there were 48546, 29081, 16116, 28097 incident presentations of each respective eGFR cohort and AKD. Classifications of socioeconomic position by household and neighborhood were related but complex, and frequently did not match. Compared to households of professionals, people with early kidney disease in unskilled or unemployed households had increased mortality (adjusted hazard ratios: 95% confidence intervals) of (1.26: 1.19-1.32) and (1.77: 1.60-1.96), respectively with adjustment for neighborhood indices making little difference. Those within either a deprived household or deprived neighborhood experienced greater mortality, but those within both had the poorest outcomes. Unskilled and unemployed households frequently reported being limited by illness, adverse mental health, living alone, basic accommodation, lack of car ownership, language difficulties, and visual and hearing impairments. Thus, impacts of deprivation on kidney health are spread throughout society-complex, serious, and not confined to those living in deprived neighborhoods.

Chronic kidney disease and the global public health agenda: an international consensus

Early detection is a key strategy to prevent kidney disease, its progression and related complications, but numerous studies show that awareness of kidney disease at the population level is low. Therefore, increasing knowledge and implementing sustainable solutions for early detection of kidney disease are public health priorities. Economic and epidemiological data underscore why kidney disease should be placed on the global public health agenda - kidney disease prevalence is increasing globally and it is now the seventh leading risk factor for mortality worldwide. Moreover, demographic trends, the obesity epidemic and the sequelae of climate change are all likely to increase kidney disease prevalence further, with serious implications for survival, quality of life and health care spending worldwide. Importantly, the burden of kidney disease is highest among historically disadvantaged populations that often have limited access to optimal kidney disease therapies, which greatly contributes to current socioeconomic disparities in health outcomes. This joint statement from the International Society of Nephrology, European Renal Association and American Society of Nephrology, supported by three other regional nephrology societies, advocates for the inclusion of kidney disease in the current WHO statement on major non-communicable disease drivers of premature mortality.

Comorbidity patterns in cardiovascular diseases: the role of life-stage and socioeconomic status

Cardiovascular diseases stand as a prominent global cause of mortality, their intricate origins often entwined with comorbidities and multimorbid conditions. Acknowledging the pivotal roles of age, sex, and social determinants of health in shaping the onset and progression of these diseases, our study delves into the nuanced interplay between life-stage, socioeconomic status, and comorbidity patterns within cardiovascular diseases. Leveraging data from a cross-sectional survey encompassing Mexican adults, we unearth a robust association between these variables and the prevalence of comorbidities linked to cardiovascular conditions. To foster a comprehensive understanding of multimorbidity patterns across diverse life-stages, we scrutinize an extensive dataset comprising 47,377 cases diagnosed with cardiovascular ailments at Mexico's national reference hospital. Extracting sociodemographic details, primary diagnoses prompting hospitalization, and additional conditions identified through ICD-10 codes, we unveil subtle yet significant associations and discuss pertinent specific cases. Our results underscore a noteworthy trend: younger patients of lower socioeconomic status exhibit a heightened likelihood of cardiovascular comorbidities compared to their older counterparts with a higher socioeconomic status. By empowering clinicians to discern non-evident comorbidities, our study aims to refine therapeutic designs. These findings offer profound insights into the intricate interplay among life-stage, socioeconomic status, and comorbidity patterns within cardiovascular diseases. Armed with data-supported approaches that account for these factors, clinical practices stand to be enhanced, and public health policies informed, ultimately advancing the prevention and management of cardiovascular disease in Mexico.

Medical Nutrition Therapy for Chronic Kidney Disease: Low Access and Utilization

CKD affects approximately half of US adults aged 65 years and older and accounts for almost 1 out of every 4 dollars of total Medicare fee-for-service spending. Efforts to prevent or slow CKD progression are urgently needed to reduce the incidence of kidney failure and reduce health care expenditures. Current CKD care guidelines recommend medical nutrition therapy (MNT), a personalized, evidence-based application of the Nutrition Care Process (assessment, intervention, diagnosis, and monitoring and evaluation) provided by registered dietitian nutritionists (RDNs) to help slow CKD progression, improve quality of life, and delay kidney failure. MNT is covered by Medicare Part B and most private insurances with no cost sharing. Despite recommendations that patients with CKD receive MNT and insurance coverage for MNT, utilization remains low. This article demonstrates low utilization of MNT and inadequate numbers of RDNs and RDNs who are board certified in renal nutrition relative to the estimated number of Medicare eligible adults with self-reported diagnosed CKD by state, with noted disparities across states. We discuss interventions to increase MNT utilization, such as improving MNT reimbursement, augmenting accessibility of RDNs via telenutrition services and increasing health care provider promotion of MNT and referral to MNT to optimize CKD outcomes.

Smokeless tobacco consumption and its association with risk factors of chronic kidney disease in rural and peri-urban Bangladesh

INTRODUCTION

Compared to smoking, which has major consequences in chronic kidney disease (CKD) initiation and progression, smokeless tobacco (SLT) consumption is considered to have fewer health consequences. We investigated the prevalence of SLT consumption and its association with risk factors of CKD in a rural and peri-urban Bangladeshi population.

METHODS

Using random sampling we recruited 872 adults in 2020, from the Mirzapur Demographic Surveillance System of Bangladesh, who had resided in the area for at least five years. Interviews using a semi-structured questionnaire, physical examination and anthropometric measurements were done, followed by blood and urine testing. The blood and urine tests were repeated in selected participants after three months as per the CKD Epidemiology Collaboration equation.

RESULTS

The prevalence of SLT consumption was 29%. Being aged ≥46 years (OR=7.10; 95% CI: 4.79-10.94), female (OR=1.64; 95% CI: 1.21-2.22), housewife (OR=1.82; 95% CI: 1.35-2.45), farmer (OR=1.71; 95% CI: 1.06-2.76), widow (OR=3.40; 95% CI: 2.24-5.17), and having no formal schooling (OR=4.91; 95% CI: 3.59-6.72), family income of <$100/month (OR=1.66; 95% CI: 1.13-2.43), sleeping duration <7 hours per day (OR=2.33; 95% CI: 1.70-3.19), were associated with a significantly higher odds of SLT consumption. However, being aged 31-45 years (OR=0.25; 95% CI: 0.16-0.38) had significantly lower odds of being an SLT consumer. Among the diseases investigated, undernutrition (OR=1.63; 95% CI: 1.15-2.33), hypertension (OR=1.52; 95% CI: 1.13-2.05), anemia (OR=1.94; 95% CI: 1.39-2.71) and CKD (OR=1.62; 95% CI: 1.15-2.27) were significantly associated with SLT consumption. In the multivariable analysis, being aged 31-45 years (AOR=3.06; 95% CI: 1.91-4.90), ≥46 years (AOR=15.69; 95% CI: 4.64-53.09) and having no formal schooling (AOR=2.47; 95% CI: 1.72-3.55) were found to have a significant association with being an SLT consumer.

CONCLUSIONS

SLT consumption is associated with most of the established risk factors of CKD within the studied population.

Association of Educational Attainment With Incidence of CKD in Young Adults

Introduction

Chronic kidney disease (CKD) is greatly affected by social determinants of health. Whether low educational attainment is associated with incident CKD in young adults is unclear.

Methods

We evaluated the association of education with incident CKD in 3139 Coronary Artery Risk Development in Young Adults participants. We categorized education into low (high school and less), medium (college), and high (master’s and professional studies) groups. Incident CKD was defined as new development of estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m² or urine albumin to creatinine ratio (ACR) ≥30 mg/g. Change in eGFR over 20 years was a secondary outcome.

Results

At baseline, mean age was 35.0 ± 3.6 years, 47% were Black, and 55% were women. Participants with lower educational attainment were less likely to have high income and health insurance and to engage in a healthy lifestyle. Over 20 years, 407 participants developed CKD (13%). Compared with individuals with low educational attainment, those with medium and high educational attainment had an unadjusted hazard ratios for CKD of 0.79 (95% confidence interval [CI] 0.65–0.97) and 0.44 (95% CI, 0.30–0.63), respectively. This association was no longer significant after adjusting for income, health insurance, lifestyle, and health status. Low educational attainment was significantly associated with a change in eGFR in crude and adjusted analyses, although the association was attenuated in the multivariable models (low: –0.83 [95% CI, –0.91 to –0.75], medium: –0.80 (95% CI, –0.95 to –0.64), and high: –0.70 (95% CI, –0.89 to –0.52) ml/min per 1.73 m² per yr).

Conclusions

Health care access, lifestyle, and comorbid conditions likely help explain the association between low educational attainment and incident CKD in young adults.

Racialized algorithms for kidney function: Erasing social experience

The rise of evidence-based medicine, medical informatics, and genomics --- together with growing enthusiasm for machine learning and other types of algorithms to standardize medical decision-making --- has lent increasing credibility to biomedical knowledge as a guide to the practice of medicine. At the same time, concern over the lack of attention to the underlying assumptions and unintended health consequences of such practices, particularly the widespread use of race-based algorithms, from the simple to the complex, has caught the attention of both physicians and social scientists. Epistemological debates over the meaning of "the social" and "the scientific" are consequential in discussions of race and racism in medicine. In this paper, we examine the socio-scientific processes by which one algorithm that "corrects" for kidney function in African Americans became central to knowledge production about chronic kidney disease (CKD). Correction factors are now used extensively and routinely in clinical laboratories and medical practices throughout the US. Drawing on close textual analysis of the biomedical literature, we use the theoretical frameworks of science and technology studies to critically analyze the initial development of the race-based algorithm, its uptake, and its normalization. We argue that race correction of kidney function is a racialized biomedical practice that contributes to the consolidation of a long-established hierarchy of difference in medicine. Consequentially, correcting for race in the assessment of kidney function masks the complexity of the lived experience of societal neglect that damages health.

Understanding the Link between Neighborhoods and Kidney Disease

Neighborhoods are where we live, learn, work, pray, and play. Growing evidence indicates that neighborhoods are an important determinant of health. The built features of our neighborhoods, such as the ways in which the streets are designed and connected and the availability of green spaces and transit stops, as well as the social features, such as the trust among neighbors and the perceptions of safety, may influence health through multiple pathways, such as access to important resources, psychosocial stress, and health behaviors. In particular, the extant literature consistently documents an association between neighborhood features and renal-associated conditions, such as cardiovascular disease, hypertension, diabetes, and obesity. There is also some evidence suggesting an association between neighborhood poverty and ESKD. The link between neighborhood and earlier stages of CKD, however, has been less clear, with most studies documenting no association. It may be that the neighborhood measures used in previous studies do not capture features of the neighborhood important for earlier stages of disease development and progression. It may also be that our current biomarkers (e.g., eGFR) and urine protein are not able to pick up very early forms of renal damage because of the kidney's overall high reserve capacity. This paper critically reviews the state of the literature on neighborhood and renal disease, with recommendations for neighborhood measures in future research. Neighborhoods are designed, built, and informed by policy, and thus, they are amenable to intervention, making them a potentially powerful way to improve renal health and reduce health inequalities at the population level.

Racial and health insurance disparities in pediatric acute kidney injury in the USA

BACKGROUND

Acute kidney injury (AKI) significantly increases morbidity and mortality for hospitalized children, yet sociodemographic risk factors for pediatric AKI are poorly described. We examined sociodemographic differences in pediatric AKI amongst a national cohort of hospitalized children.

METHODS

Secondary analysis of the most recent (2012) Kids' Inpatient Database (KID) from the Agency for Healthcare Research and Quality. Study sample weights were used to obtain national estimates of AKI (defined by administrative data). KID is a nationally representative sample of pediatric discharges throughout the USA. Linear risk regression models were used to assess the relationship between our primary exposures (race/ethnicity, health insurance, household urbanization, gender, and age) and the diagnosis of AKI, adjusting for comorbidities.

RESULTS

A total of 1,699,841 hospitalizations met our study criteria. In 2012, AKI occurred in approximately 12.3/1000 pediatric hospitalizations, which translates to almost 30,000 children nationally. Asian/Pacific Islander, African-American, and Hispanic children were at slightly increased risk for AKI compared to Caucasian children (adjusted risk difference (RD) 4.5 per 1000 hospitalizations, 95% confidence interval (CI) 2.9-6.0; 2.5/1000 hospitalizations, 95% CI 1.7-3.3; and 1.7/1000 hospitalizations, 95% CI 0.9-2.5, respectively). Uninsured children were more likely to suffer AKI compared to children with any health insurance (e.g., no insurance versus Medicaid: adjusted RD 14.4/1000 hospitalizations, 95% CI 12.7-16.2). Based on these national estimates, one episode of AKI might be prevented if 70 (95% CI 62-79) hospitalized children without insurance were provided with Medicaid.

CONCLUSIONS

Pediatric AKI occurs more frequently in racial minority and uninsured children, factors linked to lower socioeconomic status.

Social Determinants of CKD Hotspots

Chronic kidney disease (CKD) hotspots are defined as countries, regions, communities, or ethnicities with a higher than average incidence of CKD when compared with the worldwide, country, or regional rates. Here, we describe what is known about socially determined CKD hotspots, that is, the burden of CKD among socially defined communities that often collocate geographically. We focus on the poor, the homeless, and the food insecure, and their intersection with other social determinants of health, including race/ethnicity. In addition to discussing the burden of CKD in these communities, we describe some efforts to mitigate this burden and identify gaps in current knowledge.

Socioeconomic Position and Incidence of Glomerular Diseases

BACKGROUND AND OBJECTIVES

Social deprivation is a recognized risk factor for undifferentiated CKD; however, its association with glomerular disease is less well understood. We sought to investigate the relationship between socioeconomic position and the population-level incidence of biopsy-proven glomerular diseases.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective cohort study, a provincial kidney pathology database (2000-2012) was used to capture all incident cases of membranous nephropathy (n=392), IgA nephropathy (n=818), FSGS (n=375), ANCA-related GN (ANCA-GN, n=387), and lupus nephritis (n=389) in British Columbia, Canada. Quintiles of area-level household income were used as a proxy for socioeconomic position, accounting for regional differences in living costs. Incidence rates were direct standardized to the provincial population using census data for age and sex and were used to generate standardized rate ratios. For lupus nephritis, age standardization was performed separately in men and women.

RESULTS

A graded increase in standardized incidence with lower income was observed for lupus nephritis (P<0.001 for trend in both sexes) and ANCA-GN (P=0.04 for trend). For example, compared with the highest quintile, the lowest income quintile had a standardized rate ratio of 1.7 (95% confidence interval, 1.19 to 2.42) in women with lupus nephritis and a standardized rate ratio of 1.5 (95% confidence interval, 1.09 to 2.06) in ANCA-GN. The association between income and FSGS was less consistent, in that only the lowest income quintile was associated with a higher incidence of disease (standardized rate ratio, 1.55; 95% confidence interval, 1.13 to 2.13). No significant associations were demonstrated for IgA nephropathy or membranous nephropathy.

CONCLUSIONS

Using population-level data and a centralized pathology database, we observed an inverse association between socioeconomic position and the standardized incidence of lupus nephritis and ANCA-GN.

The association of neighborhood racial mix and ED visit count in a cohort of patients on hemodialysis

Background

Neighborhood racial mix is associated with dialysis facility performance metrics and mortality outcomes in patients on hemodialysis. We explored the association of neighborhood racial mix with emergency department (ED) visits in patients receiving hemodialysis.

Methods

Using Looking Glass (Montefiore’s clinical database) we identified a cohort of patients on hemodialysis with an index ED visit at any of 4 Montefiore Hospital locations, between January 2013 and December 2017 and followed it for number of ED visits through December of 2017 or dropout due to death. The racial mix data for the Bronx block group of each subject’s residence was derived from the Census Bureau. We then used negative binomial regression to test the association of quintile of percent of Black residents per residential block group with ED visits in unadjusted and adjusted models. To adjust further for quality offered by local dialysis facilities, with the facility zip code as the locus, we used data from the “Dialysis Compare” website.

Results

Three thousand nine-hundred and eighteen subjects were identified and the median number of ED visits was 3 (interquartile range (IQR) 1–7) during the study period. Subjects living in the highest quintile of percent Black residents were older, more commonly female and had lower poverty rates and higher rates of high school diplomas. Unadjusted models showed a significant association between the highest quintiles of Black neighborhood residence and count of ED visits. Fully adjusted, stratified models revealed that among males, and Hispanic and White subjects, living in neighborhoods with the highest quintiles of Black residents was associated with significantly more ED visits (p-trend =0.001, 0.02, 0.01 respectively). No association was found between dialysis facility locations’ quintile of Black residents and quality metrics.

Conclusions

Living in a neighborhood with a higher percentage of Black residents is associated with a higher number of ED visits in males and non-Black patients on hemodialysis.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1520-x) contains supplementary material, which is available to authorized users.

Use of GLP-1 receptor agonists in patients with T2DM and chronic kidney disease

Diabetes mellitus is the leading cause of chronic kidney disease (CKD) in the US. An increasing number of glucagon-like peptide-1 receptor agonists are available for diabetes management. Differences between medications in this class, as well as limited data on patients with CKD, underscore the importance of a patient-centered approach to care.

Neighborhood Social Context and Kidney Function Over Time: The Multi-Ethnic Study of Atherosclerosis

RATIONALE & OBJECTIVE

Although socioeconomic status has been associated with chronic kidney disease (CKD), little is known about its relationship to residential neighborhood context.

STUDY DESIGN

Secondary analysis of the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study designed to investigate the development and progression of subclinical cardiovascular disease.

SETTING & PARTICIPANTS

6,814 men and women who were between 45 and 84 years of age and free of cardiovascular disease were recruited between 2000 and 2002 from Baltimore, MD; Chicago, IL; Forsyth County, NC; Los Angeles, CA; New York, NY; and St. Paul, MN.

EXPOSURES

A composite neighborhood problem score (calculated based on 7 participant-reported domains at study entry: adequacy of food sources, availability of parks/playground, noise, sidewalks, traffic, trash and litter, and violence) and a social cohesion score (calculated based on 5 participant-reported attributes of people in their neighborhood: close knit; get along; willing to help neighbors; trustworthy; and share values).

OUTCOMES

Estimated glomerular filtration rate (eGFR; calculated using the CKD-EPI [CKD Epidemiology Collaboration] creatinine-cystatin C equation) and an indicator of eGFR decline > 30% since study entry using follow-up eGFR quantified at 4 examinations: 2000 to 2002, 2004 to 2005, 2005 to 2007, and 2010 to 2011.

ANALYTICAL APPROACH

Associations between each neighborhood measure (in separate models) and eGFR decline > 30% from baseline and annualized eGFR change were estimated using Cox proportional hazards and linear mixed regression models, respectively, adjusting for potential confounders.

RESULTS

While neighborhood social context differs by race/ethnicity, neither neighborhood problems nor social cohesion was independently associated with eGFR decline after adjustment for confounders.

LIMITATIONS

Incomplete capture of the early stages of eGFR decline, reliance on observational data, limited variation in neighborhood measures, and the potential for residual confounding.

CONCLUSIONS

Although we showed no independent association between neighborhood context and eGFR decline, it is associated with many CKD risk factors and further work is needed to clarify whether it has an independent role in CKD.

Kidney Disease in Women is Associated with Disadvantaged Childhood Socioeconomic Position

BACKGROUND

Socioeconomic position (SEP) is an important determinant of health and it is dynamic across the entire lifespan. We sought to investigate the relationship between life-course SEP and chronic kidney disease (CKD) using 3 conceptual models: critical period, pathway and accumulation.

METHODS

Cross-sectional analysis of 4,996 participants from The Irish Longitudinal Study on Ageing, a nationally representative cohort of community-dwelling adults aged ≥50 years. We defined childhood and adulthood SEP according to father's and respondent's occupation respectively. SEP was categorised as high (reference), intermediate, low and never worked. CKD was defined as a glomerular filtration rate < 60 mL/min/1.73 m2 estimated from the combination of creatinine and cystatin C. We used logistic regression to estimate the age-adjusted association between SEP and CKD separately in men and women.

RESULTS

Low childhood SEP was strongly associated with CKD in women, after adjusting for adulthood SEP (OR 1.90 [95% CI 1.24-2.92]), supporting the critical period hypothesis. This association was not explained by traditional CKD risk factors. Women who experienced low childhood SEP and whose circumstances improved in adulthood also had increased odds of CKD, further supporting a critical period effect in childhood. There was comparatively less evidence in support of the pathway or accumulation models. We did not observe a statistically significant association between SEP and CKD in men.

CONCLUSIONS

Our findings suggest that women exposed to disadvantaged SEP in childhood represent an at-risk group in whom there may be opportunities for identification of CKD and facilitation of health-promoting behaviours from an early age.

Associations between socioeconomic status and chronic kidney disease: a meta-analysis

BACKGROUND

Socioeconomic status (SES) has long been conjectured to be associated with the incidence and progression of chronic kidney disease (CKD), but few studies have examined this quantitatively. This meta-analysis aims to fill this gap.

METHODS

A systematic literature review was performed using Medline and EMBASE to identify observational studies on associations between SES and incidence and progression of CKD, published between 1974 and March 2017. Individual results were meta-analysed using a random effects model, in line with Meta-analysis of Observational Studies in Epidemiology guidelines.

RESULTS

In total, 43 articles met our inclusion criteria. CKD prevalence was associated with several indicators of SES, particularly lower income (OR 1.34, 95% CI (1.18 to 1.53), P<0.001; I²=73.0%, P=0.05); lower education (OR 1.21, 95% CI (1.11 to 1.32), P<0.001; I²=45.20%, P=0.034); and lower combined SES (OR 2.18, 95% CI (1.64 to 2.89), P<0.001; I²=0.0%, P=0.326). Lower levels of income, occupation and combined SES were also significantly associated with progression to end-stage renal disease (risk ratio (RR) 1.24, 95% CI (1.12 to 1.37), P<0.001; I²=66.6%, P=0.006; RR 1.05, 95% CI (1.01 to 1.09), P=0.012; I²=0.0%, P=0.796; and RR 1.39, 95% CI (1.09 to 1.79), P=0.009; I²=74.2%, P=0.009). Subgroup analyses generally confirmed these results, except in a few cases, such as an inverse association related to particular socioeconomic backgrounds and where results were adjusted by more disease-related risk factors.

CONCLUSION

Lower income was most closely associated with prevalence and progression of CKD, and lower education was significantly associated with its prevalence. Evidence for other indicators was inconclusive.

Maternal determinants of renal mass and function in the fetus and neonate

The impact of adverse maternal and early gestational issues, ranging from maternal-fetal interactions all the way through to premature birth, are recognized as having influence on the subsequent development of chronic diseases later in life. The development of chronic kidney disease (CKD) as a direct result of early life renal injury or a sequela of diseases such as hypertension or diabetes is a good model example of the potential impact that early life events may have on renal development and lifelong function. The global monetary and human resource cost of CKD is exorbitant. Socio-economic factors, along with other factors (genetic and environmental) may significantly influence the timing and display of phenotypic expression in fetuses and neonates at risk for developing CKD, yet very few of these factors are studied or well understood. In general our focus has been directed at treatment once CKD is established. This strategy has been and remains short-sighted and costly. Earlier understanding of the intrauterine determinants of renal mass development (i.e. environmental "biomes", poor maternal-fetal health, socio-economic factors impacting early life events, diet, access to value based health care and educational opportunities on disease evolution) may allow us an opportunity for earlier intervention. This article aims to provide some foundation for improved understanding of the maternal determinants of renal mass and function in the fetus and neonate.

Social Determinants of Racial Disparities in CKD

Significant disparities in CKD rates and outcomes exist between black and white Americans. Health disparities are defined as health differences that adversely affect disadvantaged populations, on the basis of one or more health outcomes. CKD is the complex result of genetic and environmental factors, reflecting the balance of nature and nurture. Social determinants of health have an important role as environmental components, especially for black populations, who are disproportionately disadvantaged. Understanding the social determinants of health and appreciating the underlying differences associated with meaningful clinical outcomes may help nephrologists treat all their patients with CKD in an optimal manner. Altering the social determinants of health, although difficult, may embody important policy and research efforts, with the ultimate goal of improving outcomes for patients with kidney diseases, and minimizing the disparities between groups.

Effects of socioeconomic status on physical and mental health of hemodialysis patients in Japan: differences by age, period, and cohort

Study purpose

Whether or not socioeconomic status (SES)-related differences in the health of hemodialysis patients differ by age, period, and birth cohort remains unclear. We examined whether SES-related gaps in physical and mental health change with age, period, and birth cohort for hemodialysis patients.

Methods

Data were obtained from repeated cross-sectional surveys conducted in 1996, 2001, 2006, and 2011, with members of a national patients’ association as participants. We used raking adjustment to create a database which had similar characteristics to the total sample of dialysis patients in Japan. SES was assessed using family size-adjusted income levels. We divided patients into three groups based on their income levels: below the first quartile, over the second quartile and under the third quartile, and over the fourth quartile. We used the number of dialysis complications as a physical health indicator and depressive symptoms as a mental health indicator. We used a cross-classified random-effects model that estimated fixed effects of age categories and period as level-1 factors, and random effects of birth cohort as level-2 factors.

Results

Relative risk of dialysis complications in respondents below the first quartile compared with ones over the fourth quartile was reduced in age categories >60 years. Mean differences in depressive symptoms between respondents below the first quartile and ones over the fourth quartile peaked in the 50- to 59-year-old age group, and were reduced in age groups >60 years. In addition, mean differences varied across periods, widening from 1996 to 2006. There were no significant birth cohort effects on income differences for dialysis complications or depressive symptoms.

Conclusion

The number of dialysis complications and depressive symptoms in dialysis patients were affected by income differences, and the degree of these differences changed with age category and period.

Matching the Genotype in Resolution: Innovative Ways of Phenotype Capture

Social and spatial context are important determinants of morbidity and mortality. However, there is little clarity about the role of context for kidney disease specifically, particularly before the end stage. Meanwhile, research clarifying the clinical, cellular, molecular, and genetic causes of kidney disease is accelerating considerably. We postulate that without contextual information, even the most detailed biomedical information cannot fully capture the factors that ultimately drive the development and progression of kidney disease. The Nephrotic Syndrome Study Network is integrating detailed, state-of-the-art information on a social and spatial context to enable the exploration of the associations between the social environment and kidney disease. Here, we discuss the extant literature on social context and kidney disease, present information on sources of contextual information, and provide recommended further reading to facilitate future research on the contribution of the social context to kidney disease.

Estimating the glomerular filtration rate in the Spanish working population: chronic kidney disease prevalence and its association with risk factors

OBJECTIVE

This study aims to investigate the influence of estimated glomerular filtration rate (eGFR) with two equations (and by one or two separate measurements), on the prevalence of chronic kidney disease (CKD) and its association with blood pressure, and cardiovascular and metabolic risk factors.

METHODS

Between January 2010 and October 2011, the Ibermutuamur CArdiovascular RIsk Assessment project included 128 588 workers (77.2% men, mean age 39.3 years, range 16-75), who underwent two consecutive yearly medical check-ups and had information for eGFR according to the MDRD-IDMS and CKD-EPI equations (serum creatinine was measured by a isotope-dilution mass spectrometry traceable method in a single central laboratory). CKD was defined by an eGFR less than 60 ml/min per 1.73 m. Subclinical (occult) renal disease was defined as an eGFR less than 60 ml/min per 1.73 m in patients with serum creatinine below 1.3 mg/dl and below 1.2 mg/dl in men and women, respectively.

RESULTS

In this working population, prevalence of CKD was very low, but two to six times lower when two separate eGFRs below 60 ml/min per 1.73 m were used. The prevalence of CKD was significantly lower with the CKD-EPI compared to the MDRD-IDMS equation. The same applies to occult CKD. In male workers, occult CKD was practically nonexistent.Multivariate analyses show that blood pressure, total serum cholesterol, and serum glucose (positively), and high-density lipoprotein and low-density lipoprotein (negatively) were associated with CKD, with both equations. Another metabolic factor (waist circumference) was only associated (positively) with CKD defined by the CKD-EPI equation, which appears to be associated with most components of the metabolic syndrome.

CONCLUSIONS

The CKD-EPI formula, calculated on the basis of two reported blood samples, may provide the most specific definition of CKD.

Race and ethnicity influences on cardiovascular and renal events in patients with diabetes mellitus

BACKGROUND

The incidence of end-stage renal disease (ESRD) has been consistently shown to be higher among blacks and Hispanics compared to whites with unmeasured risk factors and access to care as suggested explanations. In a high-risk cohort with frequent protocol-directed follow-up, we evaluated the influence of race on cardiovascular (CV) outcomes and incidence of ESRD.

METHODS

TREAT was a randomized, double-blind, placebo-controlled study. This secondary analysis focused on role of race on outcomes. TREAT enrolled 4,038 patients with type 2 diabetes, chronic kidney disease (estimated glomerular filtration rate 20-60 mL/min per 1.73 m(2)), and anemia (hemoglobin level ≤11 g/dL) treated with either darbepoetin alfa or placebo. We compared self-described black and Hispanic patients to white patients with regard to baseline characteristics and outcomes, including mortality, CV outcomes (myocardial infarction, stroke, heart failure, resuscitated sudden death, and coronary revascularization), and incident ESRD. Multivariate adjusted Cox models were developed for these outcomes.

RESULTS

Black and Hispanic patients were younger, more likely women, had less prior CV disease, and higher blood pressure. During a mean follow-up of 2.4 years with comparable access to care, blacks and Hispanics had a greater risk of ESRD but a significant lower risk of myocardial infarction and coronary revascularization than whites. After adjusting for confounders, blacks remained at significantly greater risk of ESRD than whites (hazard ratio 1.53, 95% CI 1.26-1.85, P < .001), whereas this ESRD risk did not persist among Hispanics.

CONCLUSION

Despite similar access to care and lower CV event rates, the risk of ESRD was higher among blacks and Hispanics than whites. For blacks, but not Hispanics, this increase was independent of known attributable risk factors.

Number of people in the United States experiencing ambulatory and independent living difficulties

Estimating the characteristics of the "disabled" population is necessary for some governments and of interest to health researchers concerned with producing disability prevalence rates. Because generating easy-to-understand estimates of disability in the population is important, this article provides U.S. population estimates for two disability-related measures by using the 2009 to 2011 American Community Survey Public Use Microdata Sample file. The number of people who have "independent living" and "ambulatory" difficulties is calculated from a sample of 9,204,437 (representing >309 million people). The percentage for "disabled" is found to vary by racial and ethnic category, sex, age, citizenship status, educational attainment, and state-level regions divided by weather.

Early-life course socioeconomic factors and chronic kidney disease

Kidney failure or ESRD affects approximately 650,000 Americans, whereas the number with earlier stages of CKD is much higher. Although CKD and ESRD are usually associated with adulthood, it is likely that the initial stages of CKD begin early in life. Many of these pathways are associated with low birth weight and disadvantaged socioeconomic status (SES) in childhood, translating childhood risk into later-life CKD and kidney failure. Social factors are thought to be fundamental causes of disease. Although the relationship between adult SES and CKD has been well established, the role of early childhood SES for CKD risk remains obscure. This review provides a rationale for examining the association between early-life SES and CKD. By collecting data on early-life SES and CKD, the interaction with other periods in the life course could also be studied, allowing for examination of whether SES trajectories (eg, poverty followed by affluence) or cumulative burden (eg, poverty at multiple time points) are more relevant to lifetime CKD risk.

Contextual poverty, nutrition, and chronic kidney disease

Nutrition plays an important role in CKD outcomes. One of the strongest factors that affects nutrition is socioeconomic status as evidenced by the large body of epidemiologic data showing that income and education are directly associated with diet quality. Apart from individual-level markers of socioeconomic status such as income and education, contextual factors such as availability of and transportation to food outlets that provide healthy food options and the density of fast-food restaurants within particular regions markedly affect the ability of individuals to comply with nutrition recommendations. This is particularly true for nutrition guidelines most specific to individuals with CKD such as the consumption of protein, saturated fat, sodium, and phosphorus, all of which have been shown to affect CKD health and are influenced by the availability of healthy food options within individual neighborhood food environments. Because of the strong association of contextual poverty with the diet quality, any serious attempt to improve the diet of CKD patients must include a discussion of the environmental barriers that each individual faces in trying to access healthy foods, and health care providers should take account of these barriers when tailoring specific recommendations.

Modifiable lifestyle and social factors affect chronic kidney disease in high-risk individuals with type 2 diabetes mellitus

This observational study examined the association between modifiable lifestyle and social factors on the incidence and progression of early chronic kidney disease (CKD) among those with type 2 diabetes. All 6972 people from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) with diabetes but without macroalbuminuria were studied. CKD progression was defined as decline in GFR of more than 5% per year, progression to end-stage renal disease, microalbuminuria, or macroalbuminuria at 5.5 years. Lifestyle/social factors included tobacco and alcohol use, physical activity, stress, financial worries, the size of the social network and education. Adjustments were made for known risks such as age, diabetes duration, GFR, albuminuria, gender, body mass index, blood pressure, fasting plasma glucose, and angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers use. Competing risk of death was considered. At study end, 31% developed CKD and 15% had died. The social network score (SNS) was a significant independent risk factor of CKD and death, reducing the risk by 11 and 22% when comparing the third to the first tertile of the SNS (odds ratios of CKD 0.89 and death 0.78). Education showed a significant association with CKD but stress and financial worries did not. Those with moderate alcohol consumption had a significantly decreased CKD risk compared with nonusers. Regular physical activity significantly decreased the risk of CKD. Thus, lifestyle is a determinant of kidney health in people at high cardiovascular risk with diabetes.

Low income, community poverty and risk of end stage renal disease

BACKGROUND

The risk of end stage renal disease (ESRD) is increased among individuals with low income and in low income communities. However, few studies have examined the relation of both individual and community socioeconomic status (SES) with incident ESRD.

METHODS

Among 23,314 U.S. adults in the population-based Reasons for Geographic and Racial Differences in Stroke study, we assessed participant differences across geospatially-linked categories of county poverty [outlier poverty, extremely high poverty, very high poverty, high poverty, neither (reference), high affluence and outlier affluence]. Multivariable Cox proportional hazards models were used to examine associations of annual household income and geospatially-linked county poverty measures with incident ESRD, while accounting for death as a competing event using the Fine and Gray method.

RESULTS

There were 158 ESRD cases during follow-up. Incident ESRD rates were 178.8 per 100,000 person-years (105 py) in high poverty outlier counties and were 76.3 /105 py in affluent outlier counties, p trend=0.06. In unadjusted competing risk models, persons residing in high poverty outlier counties had higher incidence of ESRD (which was not statistically significant) when compared to those persons residing in counties with neither high poverty nor affluence [hazard ratio (HR) 1.54, 95% Confidence Interval (CI) 0.75-3.20]. This association was markedly attenuated following adjustment for socio-demographic factors (age, sex, race, education, and income); HR 0.96, 95% CI 0.46-2.00. However, in the same adjusted model, income was independently associated with risk of ESRD [HR 3.75, 95% CI 1.62-8.64, comparing the <$20,000 income group to the >$75,000 group]. There were no statistically significant associations of county measures of poverty with incident ESRD, and no evidence of effect modification.

CONCLUSIONS

In contrast to annual family income, geospatially-linked measures of county poverty have little relation with risk of ESRD. Efforts to mitigate socioeconomic disparities in kidney disease may be best appropriated at the individual level.

End stage renal disease risk and neighbourhood deprivation: a nationwide cohort study in Sweden

BACKGROUND

Chronic kidney disease has been associated with socioeconomic disparities and neighbourhood deprivation. We aimed to determine whether there is an association between neighbourhood deprivation and end stage renal disease (ESRD), and whether this association is independent of individual-level sociodemographic factors and comorbidities.

METHODS

National Swedish data registers were used. The entire Swedish population aged 20-69 years was followed from January 1, 2001 until December 31, 2010. Data were analysed by multilevel logistic regression, with individual-level sociodemographic factors (age, marital status, family income, education level, country of birth, urban/rural status, and mobility) and comorbidities at the first level and neighbourhood deprivation at the second level.

RESULTS

Neighbourhood deprivation was significantly associated with ESRD (age-adjusted odds ratio [OR] 1.45, 95% confidence interval [CI] 1.34-1.56 in men and OR 1.59, 95% CI 1.44-1.75 in women). The ORs for ESRD in men and women living in the most deprived neighbourhoods remained significantly increased when adjusted for age and individual-level sociodemographic factors (OR 1.25, 95% CI 1.15-1.35 in men and OR 1.30, 95% CI 1.17-1.44 in women). In the full model, which took account of sociodemographic factors and comorbidities, the ORs for ESRD remained significantly increased (OR 1.17, 95% CI 1.07-1.27 in men and OR 1.18, 95% CI 1.06-1.31 in women).

CONCLUSION

Neighbourhood deprivation is independently associated with ESRD in both men and women irrespective of individual-level sociodemographic factors and comorbidities.

Escalating chronic kidney diseases of multi-factorial origin in Sri Lanka: causes, solutions, and recommendations

During the last two decades, Sri Lanka, located close to the equator, has experienced an escalating incidence of chronic kidney disease (CKD) of unknown aetiology (CKDue) in dry zonal areas. Similar incidences of unusual CKDs have been reported in the dry zonal, agricultural areas of several other equatorial countries. In Sri Lanka, the incidence of CKDue is highest in the North Central Province (NCP), where approximately 45 % of the country's paddy fields are located. However, in recent years, the disease has spread into areas adjacent to as well as distant from the NCP. The cause of CKD in Sri Lanka is unknown, and may likely due to interactions of different potential agents; thus, CKD is of multi-factorial origin (CKD-mfo). These factors include, the negative effects from overuse of agrochemicals. Nevertheless, the potential interactions and synergism between probable agents have not been studied. This systematic review discusses the proposed hypotheses and causes of CKD-mfo in Sri Lanka, and ways to decrease the incidence of this disease and to eradicate it, and provide some recommendations. During the past decade, a number of groups have investigated this disorder using different methodologies and reported various correlations, but failed to find a cause. Research has focussed on the contamination of water with heavy metals, agrochemicals, hard water, algae, ionicity, climate change, and so forth. Nevertheless, the levels of any of the pollutants or conditions reported in water in NPC are inconsistent not correlated with the prevalence of the disease, and are too low to be the sole cause of CKD-mfo. Meanwhile, several nephrotoxins prevalent in the region, including medications, leptospirosis, toxic herbs, illicit alcohol, locally grown tobacco, and petrochemicals, as well as the effects of changed habits occured over the past four decades have not been studied to date. Taken together, the geographical distribution and overall findings indicate that combinations of factors and/or their interactions are likely to precipitate CKD-mfo, which kills more than 5,000 people annually in Sri Lanka; most victims are middle-aged male farmers. Much anecdotal evidence from this region suggests that consumption of contaminated water is the most likely source of this deadly disease. Although the aetiology is unknown, prevention of this "environmentally acquired" disease seems relatively straightforward. Solutions include (a) preventing environmental pollution, (b) stopping the irresponsible use and decreasing the usage of agrochemicals, and encouraging the use of environmentally friendly agricultural methods, (c) taking proper precautions when using agrochemicals and safe disposal of their containers, (d) changing the risky behaviour of farmers and educating them to preserve the environment, and (e) providing clean potable water to all affected regions. Implementing a well-coordinated, in-depth, region-wide, broad-based research study together with a long-term effective surveillance programme across the country is essential to curbing this disease. Unless firm actions are taken promptly, more than three million healthy people in the country, live in agricultural regions, are at risk for contracting CKD-mfo and succumb to premature deaths, which are preventable.

Escalating chronic kidney diseases of multi-factorial origin in Sri Lanka: causes, solutions, and recommendations

During the last two decades, Sri Lanka, located close to the equator, has experienced an escalating incidence of chronic kidney disease (CKD) of unknown aetiology (CKDue) in dry zonal areas. Similar incidences of unusual CKDs have been reported in the dry zonal, agricultural areas of several other equatorial countries. In Sri Lanka, the incidence of CKDue is highest in the North Central Province (NCP), where approximately 45 % of the country's paddy fields are located. However, in recent years, the disease has spread into areas adjacent to as well as distant from the NCP. The cause of CKD in Sri Lanka is unknown, and may likely due to interactions of different potential agents; thus, CKD is of multi-factorial origin (CKD-mfo). These factors include, the negative effects from overuse of agrochemicals. Nevertheless, the potential interactions and synergism between probable agents have not been studied. This systematic review discusses the proposed hypotheses and causes of CKD-mfo in Sri Lanka, and ways to decrease the incidence of this disease and to eradicate it, and provide some recommendations. During the past decade, a number of groups have investigated this disorder using different methodologies and reported various correlations, but failed to find a cause. Research has focussed on the contamination of water with heavy metals, agrochemicals, hard water, algae, ionicity, climate change, and so forth. Nevertheless, the levels of any of the pollutants or conditions reported in water in NPC are inconsistent not correlated with the prevalence of the disease, and are too low to be the sole cause of CKD-mfo. Meanwhile, several nephrotoxins prevalent in the region, including medications, leptospirosis, toxic herbs, illicit alcohol, locally grown tobacco, and petrochemicals, as well as the effects of changed habits occured over the past four decades have not been studied to date. Taken together, the geographical distribution and overall findings indicate that combinations of factors and/or their interactions are likely to precipitate CKD-mfo, which kills more than 5,000 people annually in Sri Lanka; most victims are middle-aged male farmers. Much anecdotal evidence from this region suggests that consumption of contaminated water is the most likely source of this deadly disease. Although the aetiology is unknown, prevention of this "environmentally acquired" disease seems relatively straightforward. Solutions include (a) preventing environmental pollution, (b) stopping the irresponsible use and decreasing the usage of agrochemicals, and encouraging the use of environmentally friendly agricultural methods, (c) taking proper precautions when using agrochemicals and safe disposal of their containers, (d) changing the risky behaviour of farmers and educating them to preserve the environment, and (e) providing clean potable water to all affected regions. Implementing a well-coordinated, in-depth, region-wide, broad-based research study together with a long-term effective surveillance programme across the country is essential to curbing this disease. Unless firm actions are taken promptly, more than three million healthy people in the country, live in agricultural regions, are at risk for contracting CKD-mfo and succumb to premature deaths, which are preventable.

Socioeconomic factors and racial disparities in kidney disease outcomes

African Americans suffer disproportionately from advanced and progressive chronic kidney disease (CKD). Socioeconomic factors are believed to play an important role in this disparity, and likely influence African Americans' increased risk of CKD through multiple pathways. Low socioeconomic status (SES) may contribute to racial disparities in CKD because of the greater prevalence of poverty, for example, among African Americans as compared with whites. However, low SES has a stronger relation with CKD among African Americans than among whites, underscoring that the context and magnitude of socioeconomic influences on CKD outcomes varies between these populations. These socioeconomic influences may produce new or potentiate existing racial differences in biology. This review discusses what is known about the role of SES in explaining racial disparities in CKD, highlights several knowledge gaps in this area, and suggests future directions toward the elimination of disparities in CKD.

Distribution of and factors contributing to chronic kidney disease in a middle-aged working population

OBJECTIVES

To clarify the distribution of chronic kidney disease (CKD) and the factors contributing to its development and progression in middle-aged Japanese workers/employees.

METHODS

This was a retrospective study involving 3,964 men and 2,698 women aged 35-64 years in 2009 who had been followed-up until 2003. Data on proteinuria determined with a dipstick and glomerular filtration rate estimated from serum creatinine concentration (eGFR) were collected in the annual health check-ups.

RESULTS

Proteinuria was detected in 2.9 and 1.1 % of the men and women, respectively, and total CKD was detected in 16.0 and 16.1 % of the men and women respectively. Moderate or severe CKD associated a high risk of cardiovascular diseases and end-stage kidney disease was found mostly in the male subjects [2.0 (men) vs. 0.6 % (women)]. High-risk CKD was found in 3.3 % of the men aged 55-64 years. A body mass index (BMI) of ≥30, hypertension, diabetes mellitus (DM), current smoking and some job types were independently related to the development of proteinuria, while age, BMI, hypertriglyceridemia, and job types were related to total CKD. The development of high-risk CKD was related to preceding mild CKD signs of reduced eGFR and proteinuria as well as to hypertension, DM, smoking, and job type.

CONCLUSIONS

Chronic kidney disease was found in 16 % of middle-aged workers with an equal prevalence in both sexes, while high-risk CKD was found mostly in men, of whom 3.3 % were aged 55-64 years. Obesity, hypertension, DM, smoking and some job types were related to the development and progression of CKD.

The contextual influence of coal abandoned mine lands in communities and type 2 diabetes in Pennsylvania

Coal abandoned mine lands (AMLs), persistent and prevalent across Pennsylvania, offer an instructive evaluation of potential contextual influences of chronic environmental contamination (CEC) on individual health. We evaluated associations between the burden of AMLs, represented by 10 contextual metrics at the community level, and individual-level type 2 diabetes using hemoglobin A1c (HbA1c) as a biomarker. Cross-sectional and longitudinal multilevel analyses were conducted with over 28,000 diabetic primary care patients of the Geisinger Clinic. Adjusted models revealed five AML burden measures were associated (p<0.05), and three additional were borderline associated (0.05≤p≤0.10), with higher and/or change in HbA1c levels. This study provides key empirical evidence of adverse impacts of CEC in communities on an important chronic disease, illustrating the contextual effects of living in long-term degraded landscapes and communities.

Socio-economic impact in CKD

BACKGROUND

Socio-economic status (SES) may be conceptualized as an individual's position in society, as determined by their income, occupation, education, wealth, and housing situation. This review summarizes the current literature regarding associations of these markers of SES with both chronic kidney disease (CKD) and associated poor outcomes.

METHODS

Literature searches were conducted in the US National Library of Medicine, National Institutes of Health, PubMed database using the search terms "chronic kidney disease" and "chronic renal insufficiency," combined with "socio-economic status," "income," "occupation," "employment," "education," "social class," "wealth," and "housing." Articles not in the English language, using non-human subjects, or primarily concerning subjects with ESRD or acute kidney injury were excluded.

RESULTS

Income is the most-studied aspect of SES in relation to CKD, but there is increasing literature involving occupation and education as well. Additionally, the associations of CKD and its outcomes with area-level and life course SES are both burgeoning areas of research. There are several research areas that remain mostly unexplored, including the roles of wealth and housing in defining SES-related risk in CKD. Additionally, none have explored the relative utility of composite versus individual indicators of SES in predicting risk of CKD and outcomes.

CONCLUSION

Given the overwhelming evidence that SES plays an important role in the development and progression of disease, the development and testing of more targeted interventions should be a top priority in CKD research. Continuing examination of these factors, with increased rigor and focus on potentially modifiable intermediate pathways, is needed.

Prevalence of diminished kidney function in a representative sample of middle and older age adults in the Irish population

Background

The prevalence of chronic kidney disease (CKD) using available estimating equations with the Republic of Ireland is unknown.

Methods

A randomly selected population based cross-sectional study of 1,098 adults aged 45 years and older was conducted using data from the 2007 Survey of Lifestyle, Attitudes and Nutrition (SLÁN). Estimated Glomerular Filtration Rate (eGFR) was calculated from a single IDMS aligned serum creatinine using the CKD-EPI and the MDRD equations, and albumin to creatinine ratio was based on a single random urine sample.

Results

The sample clinical characteristics and demography was similar to middle and older age adults in the general Irish population, though with an underrepresentation of subjects >75 years and of males. All results are based on subjects with available blood and urine samples. Applying weighting to obtain survey based population estimates, using Irish population census data, the estimated weighted prevalence of CKD-EPI eGFR<60 mL/min/1.73m² was 11.6%, (95% confidence interval; 9.0, 14.2%), 12.0% ( 9.0, 14.2%) of men and 11.2% (7.3, 15.2%) of women. Unweighted prevalence estimates were similar at 11.8% (9.9, 13.8%). Albuminuria increased with lower CKD-EPI eGFR category. 10.1% of all subjects had albuminuria and an eGFR≥60 mL/min/1.73 m² giving an overall weighted estimated prevalence of National Kidney Foundation (NKF) defined CKD 21.3% (18.0, 24.6%), with the unadjusted estimate of 21.9% (19.5, 24.4%). MDRD related estimates for eGFR <60 mL/min/1.73 m², and NFK defined CKD were higher than CKD-EPI and differences were greater in younger and female subjects.

Conclusions

CKD is highly prevalent in middle and older aged adults within the Republic of Ireland. In this population, there is poor agreement between CKD-EPI and MDRD equations especially at higher GFRs. CKD is associated with lower educational status and poor self rated health.

Association of apolipoprotein A1 and B with kidney function and chronic kidney disease in two multiethnic population samples

BACKGROUND

Circulating lipoproteins and their protein constituents, apolipoproteins, are risk factors for chronic kidney disease (CKD). The associations between apolipoprotein A1, apolipoprotein B and their ratio with glomerular filtration rate estimated from the new CKD Epidemiology Collaboration (CKD-EPI) equation (eGFR) are not well studied in the general population.

METHODS

Associations between apolipoprotein A1, B and their ratio with the outcomes of eGFR, CKD (eGFR<60 mL/min/1.73 m2) and albuminuria were examined in the Atherosclerosis Risk in Communities study (ARIC, n=10,292, 1996-98) and the Third National Health and Nutrition Examination Survey (NHANES III, n=7023, 1988-91). Cross-sectional multivariable-adjusted analyses were performed using linear and logistic regression. Prospective analyses related baseline apolipoprotein levels to subsequent CKD incidence over 10 years using the ARIC Carotid MRI follow-up cohort (n=1659).

RESULTS

Higher apolipoprotein A1 quartiles were associated with a lower prevalence of CKD [Q4 versus Q1: odds ratio (OR) 0.73, P-trend=0.02 in ARIC; Q4 versus Q1: OR 0.53, P-trend<0.01 in NHANES III] as well as with higher eGFR (P-trend<0.01 in ARIC and NHANES III). No consistent significant associations were found for apolipoprotein B in either study. The apolipoprotein B/A1 ratio was significantly associated with eGFR across quartiles in both studies (P-trend<0.01) and with CKD in ARIC (Q4 versus Q1: OR 1.23, P-trend=0.01). Prospectively, there were trends for the association of apolipoproteins with incident CKD [Q4 versus Q1: incidence rate ratio (IRR)=0.68 for apolipoprotein A1, P-trend=0.1; Q4 versus Q1: IRR=1.35 for apolipoprotein B, P-trend=0.2]. Associations were not systematically stronger when comparing traditional lipids (total cholesterol, low-density lipoprotein or high-density lipoprotein) to apolipoproteins.

CONCLUSIONS

Higher serum apolipoprotein A1 was associated with lower prevalence of CKD and higher eGFR estimated by the CKD-EPI equation in two large multiethnic population-based samples. While apolipoprotein B showed no consistent associations, a higher apolipoprotein B/A1 ratio was significantly associated with lower eGFR in both studies. The direction and magnitude of the longitudinal associations between apolipoproteins and CKD incidence were overall similar to those observed cross-sectionally. No consistent differences became apparent between traditional lipids and apolipoproteins.

Albuminuria and racial disparities in the risk for ESRD

The causes of the increased risk for ESRD among African Americans are not completely understood. Here, we examined whether higher levels of urinary albumin excretion among African Americans contributes to this disparity. We analyzed data from 27,911 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who had urinary albumin-to-creatinine ratio (ACR) and estimated GFR (eGFR) measured at baseline. We identified incident cases of ESRD through linkage with the United States Renal Data System. At baseline, African Americans were less likely to have an eGFR <60 ml/min per 1.73 m(2) but more likely to have an ACR ≥ 30 mg/g. The incidence rates of ESRD among African Americans and whites were 204 and 58.6 cases per 100,000 person-years, respectively. After adjustment for age and gender, African Americans had a fourfold greater risk for developing ESRD (HR 4.0; 95% CI 2.8 to 5.9) compared with whites. Additional adjustment for either eGFR or ACR reduced the risk associated with African-American race to 2.3-fold (95% CI 1.5 to 3.3) or 1.8-fold (95% CI 1.2 to 2.7), respectively. Adjustment for both ACR and eGFR reduced the race-associated risk to 1.6-fold (95% CI 1.1 to 2.4). Finally, in a model that further adjusted for both eGFR and ACR, hypertension, diabetes, family income, and educational status, African-American race associated with a nonsignificant 1.4-fold (95% CI 0.9 to 2.3) higher risk for ESRD. In conclusion, the increased prevalence of albuminuria may be an important contributor to the higher risk for ESRD experienced by African Americans.

Fetal, developmental, and parental influences on cystatin C in childhood: the Uppsala Family Study

BACKGROUND

The aim was to identify determinants (biomedical and social characteristics of children and their parents) of cystatin C levels in healthy children drawn from a population sample.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

425 pairs of consecutive full siblings born 1987-1995 in Uppsala were identified using the Swedish Medical Birth Registry and invited with their parents for examination in 2000-2001.

OUTCOME

Serum cystatin C level was log-transformed and analyzed using random-effects models.

MEASUREMENTS

The examination in parents and children consisted of a nonfasting blood sample, anthropometry, and questionnaires about lifestyle and socioeconomic position. Tanner stage was used for assessment of pubertal status.

RESULTS

In age-, height-, and body mass index-adjusted analyses, cystatin C level increased by 2.6% (95% CI, 0.3%-4.8%) higher in Tanner stage 2 vs 1 girls, and 1.6% (95%CI, 0.2%-3.1%) lower in boys than girls. For every 10% increase in maternal cystatin C level, offspring cystatin C level increased by 3.0% (95% CI, 2.2%-3.8%); the equivalent effect for paternal cystatin C level was 2.1% (95% CI, 1.3%-2.9%). Lower maternal education was associated with a 2.4% (95% CI, 0.3%-4.6%) higher cystatin C level in their offspring.

LIMITATIONS

Cross-sectional study design, missing cystatin C values for subset of parents, lack of urinary measurements, no gold-standard measurement of glomerular filtration rate.

CONCLUSIONS

There are intergenerational associations of cystatin C level in families in line with previous reports of heritability of kidney disease. Lower maternal education is associated with higher cystatin C levels in their children. Further studies of healthy children are needed to explore the biological mechanisms for these findings. If cystatin C is measured, these studies will need to record pubertal stages.

Hypovitaminosis D, neighborhood poverty, and progression of chronic kidney disease in disadvantaged populations

In the United States, there are significant racial disparities in the incidence and prevalence of end-stage renal disease. The disparities are greatest for the Blacks and the magnitude of disparity is significantly greater than is evident from the incidence and prevalence data of end-stage renal disease - early stage chronic kidney disease is less common in Blacks and during that stage, mortality rate is significantly higher for that racial group. Recent studies have identified a genetic predisposition for non-diabetic renal disease among Blacks. However, genetic factors explain only part of the higher risk and the racial disparities are a result of a complex interplay of biology and sociology. Herein we focus on two factors and their role in explaining the higher risk for progression of chronic kidney disease among Blacks - one biologic (vitamin D deficiency) and one sociologic (neighborhood poverty). A greater Understanding of these factors is important in order to reduce the racial disparities in the United States.

Sex, race, and socioeconomic disparities in kidney disease in children

Racial and gender differences in the prevalence and treatment of chronic kidney disease in US children have been reported. Girls have lower rates of kidney transplantation than boys. Incidence of end-stage renal disease is twice as high among black patients compared with whites. African Americans are less likely than white patients to achieve hemoglobin targets on dialysis, are more likely to be treated with hemodialysis, and to wait longer for a transplant. Reasons for these disparities in disease burden and treatment choices are not known, but possible causes include genetic factors and socioeconomic and sociocultural influences on accessing medical care.

Poverty, race, and CKD in a racially and socioeconomically diverse urban population

BACKGROUND

Low socioeconomic status (SES) and African American race are both independently associated with end-stage renal disease and progressive chronic kidney disease (CKD). However, despite their frequent co-occurrence, the effect of low SES independent of race has not been well studied in CKD.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

2,375 community-dwelling adults aged 30-64 years residing within 12 neighborhoods selected for both socioeconomic and racial diversity in Baltimore City, MD.

PREDICTORS

Low SES (self-reported household income <125% of 2004 Department of Health and Human Services guideline), higher SES (> or =125% of guideline); white and African American race.

OUTCOMES & MEASUREMENTS

CKD defined as estimated glomerular filtration rate <60 mL/min/1.73 m(2). Logistic regression used to calculate ORs for relationship between poverty and CKD, stratified by race.

RESULTS

Of 2,375 participants, 955 were white (347 low SES and 608 higher SES) and 1,420 were African American (713 low SES and 707 higher SES). 146 (6.2%) participants had CKD. Overall, race was not associated with CKD (OR, 1.05; 95% CI, 0.57-1.96); however, African Americans had a much greater odds of advanced CKD (estimated glomerular filtration rate <30 mL/min/1.73 m(2)). Low SES was independently associated with 59% greater odds of CKD after adjustment for demographics, insurance status, and comorbid disease (OR, 1.59; 95% CI, 1.27-1.99). However, stratified by race, low SES was associated with CKD in African Americans (OR, 1.91; 95% CI, 1.54-2.38), but not whites (OR, 0.95; 95% CI, 0.58-1.55; P for interaction = 0.003).

LIMITATIONS

Cross-sectional design; findings may not be generalizable to non-urban populations.

CONCLUSIONS

Low SES has a profound relationship with CKD in African Americans, but not whites, in an urban population of adults, and its role in the racial disparities seen in CKD is worthy of further investigation.

Longitudinal formulas to estimate GFR in children with CKD

BACKGROUND AND OBJECTIVES

Whereas current GFR estimating equations approximate direct GFR measurement at a single time point, formulas that capitalize on changes in easily measured biologic parameters could improve the accuracy and precision of GFR estimation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the Chronic Kidney Disease in Children Cohort (aged 1 to 16 yr), we measured GFR by plasma disappearance of iohexol (iGFR) and biomarkers in the first two annual visits. Models took the form GFR(2) = a[GFR(1)/40](b)[X(2)/X(1)](c), where GFR(2) and GFR(1) represented the current and previous years' iGFR, 40 ml/min per 1.73 m(2) was the cohort mean, and X(2)/X(1) was the change in predictors over time. Using data from 360 participants with a median age of 12.1 yr, we evaluated the predictive performance of a past GFR measurement and 20 other variables using a two-thirds random sample of the data. A one-third sample was reserved for validation.

RESULTS

Previous iGFR measurements were strongly predictive of subsequent iGFR and adding change in height/serum creatinine significantly improved the explanatory power to 78%. In the validation set, the correlation between estimated and measured GFR was 0.88, and 48 and 88% of estimated GFRs were within 10 and 30% of observed iGFRs. When the past GFR measurement was not used, addition of change in markers to a cross-sectional model did not improve prediction.

CONCLUSIONS

Longitudinal formulas to estimate iGFR capitalize on the high predictive power of previous iGFR measurements and in this study yielded a parsimonious prediction model with the potential for assessing progression in the clinical setting.