Kidney disease in life-course socioeconomic context: the Atherosclerosis Risk in Communities (ARIC) Study

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

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

Socioeconomic status and reduced kidney function in the Whitehall II Study: role of obesity and metabolic syndrome

Background

Previous US-based studies have found that chronic kidney disease (CKD) disproportionately affects those of more adverse social circumstances. Our aim was to show the association between socioeconomic status (SES) and decreased kidney function in a European context and explore the role of obesity and metabolic syndrome. We consider the potential confounding effect of lean muscle mass.

Study Design

Cross-sectional.

Setting & Participants

White participants in the follow-up of the Whitehall II cohort: UK-based European population (age, 55-79 years; n = 5,533), of whom 4,066 men (73%) and 1,467 women (27%) with complete data were analyzed.

Predictors

Self-reported occupational grade/salary range.

Outcomes

Estimated glomerular filtration rate (GFR) using the CKD-EPI (CKD Epidemiology Collaboration) equation.

Measurements

Body mass index (BMI), serum lipid levels, blood pressure, Tanita TBF-300 body composition analyzer, impedance-derived lean mass index (LMI).

Results

Participants in a lower compared with higher occupational grade were at increased odds of having decreased GFR (age- and sex-adjusted OR, 1.31; 95% CI, 1.12-1.53; P = 0.001). Socioeconomic disparity in LMI was evident in women, but not men. After further adjustment for BMI and components of metabolic syndrome, the odds of decreased GFR in whites with a lower compared with higher occupational grade was attenuated by 23.3% (OR, 1.23; 95% CI, 1.06-1.45; P = 0.008). Adjustment for LMI explained 15% of the association between SES and estimated GFR.

Limitations

Cross-sectional design, missing data for subset of participants, no urinary data.

Conclusions

BMI and components of metabolic syndrome may explain up to a quarter of the association between low SES and decreased GFR, suggesting potential modifiable factors.

Association between insulin resistance and development of microalbuminuria in type 2 diabetes: a prospective cohort study

OBJECTIVE

An association between insulin resistance and microalbuminuria in type 2 diabetes has often been found in cross-sectional studies. We aimed to reassess this relationship in a prospective Taiwanese cohort of type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

We enrolled 738 normoalbuminuric type 2 diabetic subjects, aged 56.6 ± 9.0 years, between 2003 and 2005 and followed them through the end of 2009. Average follow-up time was 5.2 ± 0.8 years. We used urine albumin-to-creatinine ratio to define microalbuminuria and the homeostasis model assessment of insulin resistance (HOMA-IR) to assess insulin resistance. The incidence rate ratio and Cox proportional hazards model were used to evaluate the association between HOMA-IR and development of microalbuminuria.

RESULTS

We found incidences of microalbuminuria of 64.8, 83.5, 93.3, and 99.0 per 1,000 person-years for the lowest to highest quartiles of HOMA-IR. Compared with those in the lowest quartile of HOMA-IR, the incidence rate ratios for those in the 2nd, 3rd, and highest quartiles were 1.28 (95% CI 0.88-1.87), 1.44 (0.99-2.08), and 1.52 (1.06-2.20), respectively (trend test: P < 0.001). By comparison with those in the lowest quartile, the adjusted hazard ratios were 1.37 (0.93-2.02), 1.66 (1.12-2.47), and 1.76 (1.20-2.59) for those in the 2nd, 3rd, and highest HOMA-IR quartiles, respectively.

CONCLUSIONS

According to the dose-response effects of HOMA-IR shown in this prospective study, we conclude that insulin resistance could significantly predict development of microalbuminuria in type 2 diabetic patients.

Race differences in access to health care and disparities in incident chronic kidney disease in the US

BACKGROUND

The contribution of race differences in access to health care to disparities in chronic kidney disease (CKD) incidence in the United States is unknown.

METHODS

We examined race differences in usual source of health care, health insurance and CKD incidence among 3883 Whites and 1607 Blacks with hypertension or diabetes enrolled in the Atherosclerosis Risk in Communities Study. In multivariable analyses, we explored the incremental contribution of access to health care in explaining Blacks' excess CKD incidence above and beyond other socioeconomic, lifestyle and clinical factors.

RESULTS

Compared with Whites, Blacks had poorer access to health care (3 vs 0.3% with no usual source of health care or health insurance, P < 0.001) and experienced greater CKD incidence (14.7 vs 12.0 cases per 1000 person-years, P < 0.001). Blacks' excess risk of CKD persisted after adjusting for demographic, socioeconomic, lifestyle and clinical factors [hazard ratio (HR) (95% confidence interval (95% CI)) = 1.21 (1.01-1.47)]. Adjustment for these factors explained 64% of the excess risk among Blacks. The increased risk for CKD among Blacks was attenuated after additional adjustment for race differences in access to health care [HR (95% CI) = 1.19 (0.99-1.45)], which explained an additional 10% of the disparity. Conclusions. In this population at risk for developing CKD, we found that poorer access to health care among Blacks explained some of Blacks' excess risk of CKD, beyond the excess risk explained by demographic, socioeconomic, lifestyle and clinical factors. Improved access to health care for high-risk individuals could narrow disparities in CKD incidence.

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.

Association of socioeconomic status and CKD among African Americans: the Jackson Heart Study

BACKGROUND

Socioeconomic status (SES) is recognized as a key social environmental factor because it has implications for access to resources that help individuals care for themselves and others. Few studies have examined the association of SES with chronic kidney disease (CKD) in high-risk populations.

STUDY DESIGN

Single-site longitudinal population-based cohort.

SETTING & PARTICIPANTS

Data for this study were drawn from the baseline examination of the Jackson Heart Study. The analytic cohort consisted of 3,430 African American men and women living in the tricounty region of the Jackson, MS, metropolitan area with complete data to determine CKD status.

PREDICTOR

High SES (defined as having a family income at least 3.5 times the poverty level or having at least 1 undergraduate degree).

OUTCOMES & MEASUREMENTS

CKD (defined as the presence of albuminuria or decreased estimated glomerular filtration rate [<60 mL/min/1.73 m(2)]). Associations were explored using bivariable analyses and multivariable logistic regression analyses adjusting for CKD and cardiovascular disease risk factors, as well as demographic factors.

RESULTS

The prevalence of CKD in the Jackson Heart Study was 20% (865 of 3,430 participants). Proportions of the Jackson Heart Study cohort with albuminuria and decreased estimated glomerular filtration rate were 12.5% (429 of 3,430 participants) and 10.1% (347 of 3,430 participants), respectively. High SES was associated inversely with CKD. The odds of having CKD were 41% lower for affluent participants than their less affluent counterparts. There were no statistically significant interactions between sex and education or income, although subgroup analysis showed that high income was associated with CKD in men (OR, 0.47; 95% CI, 0.23-0.97), but not women (OR, 0.64; 95% CI, 0.40-1.03).

LIMITATIONS

Models were estimated using cross-sectional data.

CONCLUSION

CKD is associated with SES. Additional research is needed to elucidate the impact of wealth and social contexts in which individuals are embedded and the mediating effects of sociocultural factors.

Defining incident chronic kidney disease in the research setting: The ARIC Study

Deaths of participants and losses to follow-up pose challenges for defining outcomes in epidemiologic studies. The authors compared several definitions of incident chronic kidney disease (CKD) in terms of incidence, agreement, and risk factor associations. They used data from 14,873 participants in the community-based, multicenter, biracial Atherosclerosis Risk in Communities Study (1987-1999). The estimated glomerular filtration rate (eGFR) was based on serum creatinine at baseline and the 3- and 9-year follow-up visits. Hospitalizations were ascertained continuously. The authors compared 4 definitions of incident CKD: 1) low eGFR (<60 mL/minute/1.73 m(2)); 2) low and declining (> or =25%) eGFR; 3) an increase in serum creatinine (> or =0.4 mg/dL) at 3- or 9-year follow-ups; and 4) CKD-related hospitalization or death. From these definitions, they identified 1,086, 677, 457, and 163 cases, respectively. There was relatively good agreement among definitions 1-3, but definition 4 identified mostly different cases. Risk factor associations were consistent across definitions for hypertension and lipids. Diabetes showed weaker associations with definition 1 (incidence rate ratio = 1.5, 95% confidence interval: 1.2, 1.7) than with definition 4 (incidence rate ratio = 6.3, confidence interval: 4.4, 8.9). Associations with gender differed in direction and magnitude across definitions. Case definition can impact relative risk estimates for CKD risk factors.

Social environmental stressors, psychological factors, and kidney disease

Kidney disease is one of the most striking examples of health disparities in American public health. Disparities in the prevalence and progression of kidney disease are generally thought to be a function of group differences in the prevalence of kidney disease risk factors such as diabetes, hypertension, and obesity. However, the presence of these comorbidities does not completely explain the elevated rate of progression from chronic kidney disease (CKD) to end-stage renal disease among high-risk populations such as African Americans. We believe that the social environment is an important element in the pathway from CKD risk factors to CKD and end-stage renal disease. This review of the literature draws heavily from social science and social epidemiology to present a conceptual frame specifying how social, economic, and psychosocial factors interact to affect the risks for and the progression of kidney disease.

Poor glycemic control in diabetes and the risk of incident chronic kidney disease even in the absence of albuminuria and retinopathy: Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Diabetic nephropathy is the leading cause of kidney failure in the United States. The extent to which an elevated glycated hemoglobin (HbA(1c)) concentration is associated with increased risk of chronic kidney disease (CKD) in the absence of albuminuria and retinopathy, the hallmarks of diabetic nephropathy, is uncertain.

METHODS

Glycated hemoglobin concentration was measured in 1871 adults with diabetes mellitus followed up for 11 years in the Atherosclerosis Risk in Communities (ARIC) Study. Incident CKD was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2) after 6 years of follow-up or a kidney disease-related hospitalization. We categorized HbA(1c) concentrations into 4 clinically relevant categories. Albuminuria and retinopathy were measured midway through follow-up.

RESULTS

Higher HbA(1c) concentrations were strongly associated with risk of CKD in models adjusted for demographic data, baseline glomerular filtration rate, and cardiovascular risk factors. Compared with HbA(1c) concentrations less than 6%, HbA(1c) concentrations of 6% to 7%, 7% to 8%, and greater than 8% were associated with adjusted relative hazard ratios (95% confidence intervals) of 1.4 (0.97-1.91), 2.5 (1.70-3.66), and 3.7 (2.76-4.90), respectively. Risk of CKD was higher in individuals with albuminuria and retinopathy, and the association between HbA(1c) concentration and incident CKD was observed even in participants without either abnormality: adjusted relative hazards, 1.46 (95% confidence intervals, 0.80-2.65), 1.17 (0.43-3.19), and 3.51 (1.67-7.40), respectively; P(trend) = .004.

CONCLUSIONS

We observed a positive association between HbA(1c) concentration and incident CKD that was strong, graded, independent of traditional risk factors, and present even in the absence of albuminuria and retinopathy. Hyperglycemia is an important indicator of risk of both diabetic nephropathy with albuminuria or retinopathy and of less specific forms of CKD.

Inflammation, hemostasis, and the risk of kidney function decline in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Inflammation and hemostasis may increase the risk of kidney function decline; however, data from prospective studies are sparse.

STUDY DESIGN

The Atherosclerosis Risk in Communities (ARIC) Study, a prospective observational cohort.

SETTING & PARTICIPANTS

We used data from 14,854 middle-aged adults from 4 different US communities.

PREDICTOR

Markers of inflammation and hemostasis were examined.

OUTCOMES & MEASUREMENTS

The risk of kidney function decrease associated with these markers was studied. Glomerular filtration rate (GFR) was calculated from serum creatinine levels using the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation. Chronic kidney disease (CKD) was defined as: (1) a decrease in estimated GFR to less than 60 mL/min/1.73 m2 from greater than 60 mL/min/1.73 m2 at baseline, or (2) a hospitalization discharge or death coded for CKD. Serum creatinine was measured at baseline and the 3- and 9-year follow-up visits. Hazard ratios (HRs) of CKD associated with increased levels of inflammatory and hemostatic variables were estimated by using multivariate Cox proportional hazards regression.

RESULTS

1,787 cases of CKD developed between 1987 and 2004. After adjusting for demographics, smoking, blood pressure, diabetes, lipid levels, prior myocardial infarction, antihypertensive use, alcohol use, year of marker measurement, and baseline renal function using estimated GFR, the risk of incident CKD increased with increasing quartiles of white blood cell count (HR quartile 4 versus quartile 1, 1.30; 95% confidence interval [CI], 1.12 to 1.50; P trend = 0.001), fibrinogen (HR, 1.25; 95% CI, 1.09 to 1.44; P < 0.001), von Willebrand factor (HR, 1.46; 95% CI, 1.26 to 1.68; P < 0.001), and factor VIIIc (HR, 1.39; 95% CI, 1.20 to 1.60; P < 0.001). A strong inverse association was found between serum albumin level and risk of CKD (HR, 0.63; 95% CI, 0.55 to 0.72; P < 0.001). No independent association was found with factor VIIc level.

LIMITATIONS

Although we lacked a direct measure of kidney function, associations were robust to case definitions.

CONCLUSIONS

Markers of inflammation and hemostasis are associated with greater risk of kidney function decrease. Findings suggest that inflammation and hemostasis are antecedent pathways for CKD.

Sugary soda consumption and albuminuria: results from the National Health and Nutrition Examination Survey, 1999-2004

Background

End-stage renal disease rates rose following widespread introduction of high fructose corn syrup in the American diet, supporting speculation that fructose harms the kidney. Sugar-sweetened soda is a primary source of fructose. We therefore hypothesized that sugary soda consumption was associated with albuminuria, a sensitive marker for kidney disease.

Methodology/Principal Findings

Design was a cross-sectional analysis. Data were drawn from the National Health and Nutrition Examination Survey (NHANES), 1999–2004. The setting was a representative United States population sample. Participants included adults 20 years and older with no history of diabetes mellitus (n = 12,601); after exclusions for missing outcome and covariate information (n = 3,243), the analysis dataset consisted of 9,358 subjects. Exposure was consumption of two or more sugary soft drinks, based on 24-hour dietary recall. The main outcome measure was Albuminuria, defined by albumin to creatinine ratio cutpoints of >17 mg/g (males) and >25 mg/g (females). Logistic regression adjusted for confounders (diet soda, age, race-ethnicity, gender, poverty). Interactions between age, race-ethnicity, gender, and overweight-obesity were explored. Further analysis adjusted for potential mediators: energy intake, basal metabolic rate, obesity, hypertension, lipids, serum uric acid, smoking, energy expenditure, and glycohemoglobin. Alternative soda intake definitions and cola consumption were employed.

Results

Weighted albuminuria prevalence was 11%, and 17% consumed 2+ sugary soft drinks/day. The confounder-adjusted odds ratio for sugary soda was 1.40 (95% confidence interval: 1.13, 1.74). Associations were modified by gender (p = 0.008) and overweight-obesity (p = 0.014). Among women, the OR was 1.86 (95% CI: 1.37, 2.53); the OR among males was not significant. In the group with body mass under 25 kg/m², OR = 2.15 (95% confidence interval: 1.42, 3.25). Adjustment for potential mediators and use of alternative definitions of albuminuria and soda consumption did not appreciably change results. Diet sodas were not associated with albuminuria.

Conclusions

Findings suggest that sugary soda consumption may be associated with kidney damage, although moderate consumption of 1 or fewer sodas does not appear to be harmful. Additional studies are needed to assess whether HFCS itself, overall excess intake of sugar, or unmeasured lifestyle and confounding factors are responsible.

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

The authors investigated the cumulative effects of life course social class and neighborhood socioeconomic conditions on the prevalence of chronic kidney disease (CKD) in adulthood. Subjects were members of the Atherosclerosis Risk in Communities (ARIC) Study, a longitudinal cohort study of four US communities. CKD was defined by glomerular filtration rate <45 ml/min/1.73 m2 or hospital discharge diagnosis. Working class was defined by workplace roles for subjects and their fathers; area socioeconomic status (SES) was based on census information. Being working class for all life course periods or for some life course periods was associated with increased odds of CKD, compared to being non-working class for all periods (adjusted odds ratio, OR, for all periods (95% confidence interval) 1.4 (0.9, 2.0) in Whites and 1.9 (1.3, 2.9) in African-Americans; OR for some periods 1.3 (1.0, 1.9) in Whites and 1.4 (0.9, 2.2) in African-Americans). Low area SES over the life course was not significantly related to CKD compared to living in a higher SES areas at all life course periods. Adjustment for age, gender, community of residence, cumulative social class (for neighborhood measures), cumulative low-neighborhood SES (for cumulative individual social class), hypertension and diabetes does not account for these associations. Our conclusion is that chronic kidney disease is associated with life course socioeconomic conditions. As such, life course social class and neighborhood conditions deserve further attention in accounting for socioeconomic disparities in kidney disease.

Socioeconomic status and microalbuminuria in an Asian population

BACKGROUND

In studies from developed Western countries, lower socioeconomic status (SES) has been reported to be associated with kidney diseases. However, this hypothesis has not been examined in populations from newly industrialized Asian countries. We evaluated the association between SES and micro/macroalbuminuria in a population-based sample in Singapore.

METHODS

We examined 920 participants of Malay ethnicity aged 40-80 years (49.6% female). SES was defined through education, income and housing type of participants. The main outcome of interest was the presence of micro/macroalbuminuria defined as a urinary albumin-to-creatinine ratio (ACR) >or=17 mg/g for men and >or=25 mg/g for women.

RESULTS

Lower categories of SES were associated with micro/macroalbuminuria; compared to the higher categories of SES, the odds ratio (95% confidence interval) of micro/macroalbuminuria was 1.76 (1.23-2.52) for primary/lower education, 1.64 (1.16-2.31) for income <1000 Singapore dollars (SGD)/retired status, 1.44 (1.01-2.06) for small/medium housing type and 2.37 (1.56-3.60) for the coexistence of all three low SES factors (primary/ below education, income <1000 SGD/retired status and small/medium housing type) compared to <or=1 low SES factor. This pattern of association was consistently present in subgroup analyses by gender and age.

CONCLUSIONS

Lower SES is associated with the presence of micro/macroalbuminuria independent of age, gender, smoking, alcohol intake and body mass index among Malay adults in Singapore.

All-cause mortality attributable to chronic kidney disease: a prospective cohort study based on 462 293 adults in Taiwan

BACKGROUND

Both end-stage renal disease and chronic kidney disease are increasing worldwide; however, the full effect of chronic kidney disease is unknown because mortality risks for all five stages are unavailable. We assessed prevalence and mortality risks for all stages of chronic kidney disease and quantified its attributable mortality in Taiwan.

METHODS

The cohort consisted of 462 293 individuals aged older than 20 years who participated in a standard medical screening programme since 1994. As of Dec 31, 2006, we identified 14 436 deaths. Chronic kidney disease was determined by glomerular filtration rate and urinary protein. We estimated national prevalence in Taiwan from the cohort by adjusting age and educational levels. Hazard ratios (HRs) were calculated with Cox proportionate hazards model. We calculated mortality attributable to chronic kidney disease for national population and for low socioeconomic status.

FINDINGS

The national prevalence of chronic kidney disease was 11.93% (95% CI 11.66-12.28), but only 3.54% (3.37-3.68) of participants in the cohort were aware of their disorder. Prevalence was substantially higher in the group with low socioeconomic status than in the high status group (19.87% [19.84-19.91] vs 7.33% [7.31-7.35]). 56 977 (12%) of cohort participants had chronic kidney disease; those with disease had 83% higher mortality for all cause (HR 1.83 [1.73-1.93]) and 100% higher for cardiovascular diseases (2.00 [1.78-2.25]), in a cohort that was observed for 13 years with median follow-up of 7.5 years (IQR 4.0-10.1). 10.3% (95% CI 9.57-11.03) of deaths in the entire population were attributable to chronic kidney disease, but 17.5% (16.27-18.67) of deaths in the low socioeconomic status population. 2350 (39%) deaths occurred before 65 years of age in those with chronic kidney disease. Regular users of Chinese herbal medicines had a 20% (odds ratio 1.20 [1.16-1.24]) increased risk of developing chronic kidney disease.

INTERPRETATION

The high prevalence of chronic kidney disease and its associated all-cause mortality, especially in people with low socioeconomic status, make reduction of this disorder a public-health priority. Promotion of its recognition through the general public knowing their glomerular filtration rate and testing their urine is crucial to reduce premature deaths from all causes and to attenuate this global epidemic.

Historical records as a source of information for childhood socioeconomic status: results from a pilot study of decedents

PURPOSE

The validity of parental occupation recalled by adult children is not established, yet it is commonly used to measure childhood socioeconomic status (SES). We investigated the feasibility of using data from historical records to validate recalled parental SES.

METHODS

Data from death certificates and applications for Social Security numbers (parents' names, date and place of birth) were used to locate birth certificates and 1930 census records of 416 decedents in Forsyth County, NC, to verify parental occupation and childhood residence.

RESULTS

Birth certificates and/or census records were located for 85% of decedents. Of 257 for whom both records were searched, both were found for 60%, only a census record for 10%, and only a birth certificate for 24%. Among those with father's occupation recorded on both records (n = 138), occupational category matched on 89% of records (kappa = 0.86). Place of residence/birth, which can be linked with census-based county socioeconomic indicators, was also highly concordant across records.

CONCLUSIONS

These results demonstrate that birth and census records can be located for most decedents and that the childhood SES data contained therein is highly concordant. Thus they are an alternative to recalled childhood SES and a source of validation data in life course studies.

Prevalence and associations of anemia of CKD: Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004

BACKGROUND

Early identification of anemia of chronic kidney disease may be important for the development of preventive strategies. We compared anemia prevalence and characteristics in the National Kidney Foundation Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004 populations.

METHODS

Clinical, demographic, and laboratory data were collected from August 2000 to December 31, 2006, from participants in KEEP, a community-based health-screening program targeting individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Anemia was defined as hemoglobin level less than 13.5 g/dL for men and less than 12.0 g/dL for women (Kidney Disease Outcomes Quality Initiative [KDOQI] 2006) or less than 13.0 g/dL for men and less than 12.0 g/dL for women (World Health Organization [WHO]).

RESULTS

In KEEP (n = 70,069), 68.3% of participants, and in NHANES (n = 17,061), 52% of participants, were women. African Americans represented 33.9% of the KEEP and 11.2% of the NHANES cohorts, and Hispanics comprised 12.4% of KEEP and 13.2% of NHANES. Using the KDOQI classification, anemia was present in 13.9% and 6.3% of KEEP and NHANES participants, whereas using the WHO classification, anemia was present in 11.8% and 5.3%, respectively. In adjusted analysis of KEEP data, KDOQI-defined anemia was significantly more likely in men (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.23 to 1.37); this pattern was reversed when using WHO-defined anemia (OR, 0.68; 95% CI, 0.64 to 0.72). Adjusted odds of anemia were greater for African American than white KEEP participants (OR, 2.98; 95% CI, 2.80 to 3.16; OR, 3.00; 95% CI, 2.81 to 3.20 for KDOQI- and WHO-defined anemia, respectively).

CONCLUSION

Anemia was twice as common in the targeted KEEP chronic kidney disease screening program cohort than in the NHANES sample population. African Americans had a 3-fold increased likelihood of anemia compared with whites. Targeted screening can identify anemia in a high-risk population.

Socioeconomic status and the incidence of ESRD

BACKGROUND

Persons of low socioeconomic status (SES) may be at increased risk of end-stage renal disease (ESRD). This study examines the association between SES and incidence of ESRD caused by all primary renal diseases and caused by 3 diseases that differ in the availability of effective treatment: diabetes mellitus, lupus nephritis, and autosomal dominant polycystic kidney disease (ADPKD).

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adults with incident ESRD in the United States from January 1, 1996, to June 30, 2004 (N = 747,556).

PREDICTOR

SES, based on characteristics of the patient's ZIP code of residence.

OUTCOMES

Incidence of ESRD.

RESULTS

In all sex-race groups, the incidence of ESRD caused by all primary renal diseases was greatest in those in the lowest SES score quartile and decreased progressively with higher SES. For example, for white women, the incidence of ESRD was 388.9 per million in the lowest quartile of SES and 200.8 per million in the highest quartile of SES (relative risk, 1.92; 95% confidence interval, 1.89 to 1.95). However, this association differed among patients with primary renal diseases. There were strong associations between SES and ESRD caused by diabetes mellitus, weaker associations for ESRD caused by lupus nephritis, and generally no associations for ESRD caused by ADPKD. For example, for white women, relative risks of ESRD in the lowest compared with the highest SES quartile were 2.84 for ESRD caused by diabetes mellitus, 1.63 for ESRD caused by lupus nephritis, and 1.27 for ESRD caused by ADPKD.

LIMITATIONS

Use of an area-based measure of SES.

CONCLUSIONS

The strength of the association between SES and ESRD differs among patients with diabetes mellitus, lupus nephritis, and ADPKD, suggesting that socioeconomic factors act differently in the progression of chronic kidney disease in these conditions.