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

Immunosuppression and transplantation-related characteristics affect the difference between eGFR equations based on creatinine compared to cystatin C in kidney transplant recipients

Introduction

Previous studies show heterogeneity when applying estimated glomerular filtration (eGFR) equations to kidney transplant recipients (KTRs). However, research on the impact of transplantation-related characteristics on eGFR equations using creatinine (eGFRcr) compared to cystatin C (eGFRcys) is scarce.

Methods

We conducted a comprehensive analysis with three eGFRcr equations (Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009, European Kidney Function Consortium (EKFC) 2021, kidney recipient specific-glomerular filtration rate KRS-GFR) 2023), comparing them to two eGFRcys (CKD-EPI 2012 and EKFC 2023) in 596 KTRs. Bland-Altman plots demonstrated relative differences according to different eGFR-stages. Multivariable logistic regression identified transplantation-related characteristics independently associated with smaller or greater differences between eGFRcr and eGFRcys equations.

Results

94.3% of the cohort were White individuals. Median eGFR differed as much as 9 ml/min/1.73 m2 between equations. The median relative differences (Q2) were greater (more negative) when comparing the eGFRcr equations to eGFRcys CKD-EPI 2012, than when comparing them to eGFRcys EKFC 2023 (P < .001). Better average eGFR was associated with smaller mean relative differences in all comparisons but eGFRcr CKD-EPI 2009 with eGFR EKFC 2023 and eGFRcr EKFC 2021 with eGFRcys EKFC 2023. Living kidney donation and belatacept use were independent factors associated with a smaller difference (≥Q3) between eGFRcr and eGFRcys equations, while prednisone use or higher HbA1c were independently associated with a greater difference (≤Q1) between equations.

Conclusion

Different eGFR-stages, donor, or recipient characteristics, along with immunosuppression such as belatacept or prednisone, contribute to differences between eGFRcr and eGFRcys. These effects need to be considered in the clinical management of KTRs.

The long-lasting effect of early life family structure on social position, well-being, and biological condition in adulthood

BACKGROUND

The absence of even one parent has short- and long-term effects on the child's current and future health. The purpose of the study was to determine whether there is a long-term relationship between the type of family in which men were raised and an individual's adult social position, well-being in adulthood and their biological condition regardless of social status in adulthood.

MATERIALS AND METHODS

Data for 4528 males, aged 25-80 years, were selected from the archives of the Lower Silesian Medical Centre in Wrocław, Poland. A total of 329 men declared that they grew up in incomplete families. Height, weight, % fat, cardiovascular and respiratory systems, blood parameters, and health of men who grew up in complete or incomplete families were compared.

RESULTS

Growing up in an incomplete family reduced chances for better education, decreased life satisfaction in adulthood, and negatively affected the final height. After taking into account the education achieved, the effect persisted only for diastolic blood pressure, creatinine, and serum phosphorus levels.

CONCLUSIONS

Growing up in an incomplete family has a significant impact on male's socioeconomic position (SES), life satisfaction, and final height. A poorer quality of diet is proposed as an early life risk factor for adult health.

Aging on the Job? The Association Between Occupational Characteristics and Accelerated Biological Aging

OBJECTIVES

There is a common belief that demanding jobs can make workers age faster, but there is little empirical evidence linking occupational characteristics to accelerated biological aging. We examine how occupational categorizations and self-reported working conditions are associated with expanded biological age, which incorporates 22 biomarkers and captures physiologic dysregulation throughout several bodily systems.

METHODS

Data are from 1,133 participants in the Health and Retirement Study who were aged 51-60 and working for pay in the 2010 or 2012 wave and who participated in the 2016 Venous Blood Study. We estimate associations between occupational category (professional/managerial, sales/clerical, service, and manual) and self-reported working conditions (psychosocial demands, job control, heavy lifting, and working 55 or more hours per week) and expanded biological age.

RESULTS

Compared to same-age individuals working in professional or managerial positions, those working in service jobs appear 1.65 years older biologically even after adjusting for social and economic characteristics, self-reported working conditions, health insurance, and lifestyle-related risk factors. Low job control is associated with 1.40 years, heavy lifting with 2.08 years, and long working hours with 1.87 years of accelerated biological aging.

DISCUSSION

Adverse occupational characteristics held at midlife, particularly service work, low job control, heavy lifting, and long work hours, are associated with accelerated biological aging. These findings suggest that work may be important for the overall aging process beyond its associations with specific diseases or risk factors.

Where do you live and what do you do? Two questions that might impact your kidney health

In many cases the social determinants of health need to be assessed through their interaction with environmental factors. This review looks at the impact of physical location and occupation of individuals on their kidney health. It examines the effect of living at high altitude on kidney function and the relationship between extreme cold or hot temperatures and the incidence of kidney injury. It reviews as well the many occupations that have been linked to kidney disease in high-income and low-and-middle-income countries. As a conclusion, this overview proposes preventive recommendations that could be individualized based on weather, altitude, socio-economic level of the country and occupation of the individual.

Risk of Macrovascular and Microvascular Disease in Diabetes Diagnosed Using Oral Glucose Tolerance Test With and Without Confirmation by Hemoglobin A1c: The Whitehall II Cohort Study

BACKGROUND

It is unclear whether replacing oral glucose tolerance test (OGTT) with hemoglobin A1c (HbA1c) measurement for diagnosing diabetes is justified. We aimed to assess the proportion of OGTT-diagnosed diabetes cases that can be confirmed by HbA1c and to examine whether individuals with OGTT diagnosis but nondiagnostic HbA1c are at higher risk of macrovascular and microvascular disease.

METHODS

Participants were 5773 men and women from the population-based Whitehall II prospective cohort study in the United Kingdom. New OGTT diabetes cases diagnosed in clinical examinations in 2002 to 2004 and 2007 to 2009 were assessed for HbA1c confirmation (≥6.5%) in these and subsequent clinical examinations in 2012 to 2013 and 2015 to 2016. All participants were followed up for major cardiovascular events through linkage to electronic health records until 2017 and for incident chronic kidney disease (estimated glomerular filtration rate <60 mL·min^-1·1.73 m^-2) until the last clinical examination. In analysis of vascular disease risk, new OGTT-diagnosed diabetes cases with and without diagnostic HbA1c and preexisting diabetes cases were compared with diabetes-free participants.

RESULTS

Of the 378 (59.3%) participants with OGTT-diagnosed diabetes, 224 were confirmed by HbA1c during 4.1 years (SD, 4.1 years) of follow-up. We recorded 942 cardiovascular events over 12.1 years. After adjustment for nonmodifiable risk factors and compared with the 4997 diabetes-free participants, 371 participants with new HbA1c-confirmed diabetes and 405 participants with preexisting diabetes had increased risk of cardiovascular disease (hazard ratio, 1.53 [95% CI, 1.12-2.10] and 1.85 [95% CI, 1.50-2.28], respectively). The corresponding hazard ratios in the analysis of incident chronic kidney disease (487 cases; follow-up, 6.6 years) were 1.69 (95% CI, 1.09-2.62) for 282 participants with new HbA1c-confirmed diabetes and 1.67 (95% CI, 1.22-2.28) for 276 participants with preexisting diabetes. In both analyses, OGTT cases with nondiagnostic HbA1c (n=149 and 107) had a risk (hazard ratio, 0.99-1.07) similar to that of the diabetes-free population.

CONCLUSIONS

More than 40% of OGTT-diagnosed diabetes cases were not confirmed by HbA1c during an extended follow-up. However, because these individuals have a risk of cardiovascular disease and chronic kidney disease similar to that of the diabetes-free population, replacement of OGTT with HbA1c-based diagnosis appears justified.

The value of combining individual and small area sociodemographic data for assessing and handling selective participation in cohort studies: Evidence from the Swedish CardioPulmonary bioImage Study

Objectives

To study the value of combining individual- and neighborhood-level sociodemographic data to predict study participation and assess the effects of baseline selection on the distribution of metabolic risk factors and lifestyle factors in the Swedish CardioPulmonary bioImage Study (SCAPIS).

Methods

We linked sociodemographic register data to SCAPIS participants (n = 30,154, ages: 50–64 years) and a random sample of the study’s target population (n = 59,909). We assessed the classification ability of participation models based on individual-level data, neighborhood-level data, and combinations of both. Standardized mean differences (SMD) were used to examine how reweighting the sample to match the population affected the averages of 32 cardiopulmonary risk factors at baseline. Absolute SMDs >0.10 were considered meaningful.

Results

Combining both individual-level and neighborhood-level data gave rise to a model with better classification ability (AUC: 71.3%) than models with only individual-level (AUC: 66.9%) or neighborhood-level data (AUC: 65.5%). We observed a greater change in the distribution of risk factors when we reweighted the participants using both individual and area data. The only meaningful change was related to the (self-reported) frequency of alcohol consumption, which appears to be higher in the SCAPIS sample than in the population. The remaining risk factors did not change meaningfully.

Conclusions

Both individual- and neighborhood-level characteristics are informative in assessing study selection effects. Future analyses of cardiopulmonary outcomes in the SCAPIS cohort can benefit from our study, though the average impact of selection on risk factor distributions at baseline appears small.

Association between kidney function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study

BACKGROUND

Cognitive dysfunction is common in haemodialysis patients but whether poor kidney function in the general population is also associated with higher risk of dementia remains unclear.

OBJECTIVE

To examine the association of kidney function with incident dementia in community dwelling older adults.

DESIGN

Whitehall II prospective study.

SETTING

Population-based study on 6,050 adults, mean age 65.8 in 2007-2009.

METHODS

Poor kidney function, defined as estimated Glomerular Filtration Rate (eGFR) <60 ml/min/1.73 m2 in 2007-2009, and adverse change in eGFR was defined as decrease ≥4 ml/min/1.73 m2 between 2007-2009 and 2012-2013.Incident dementia was ascertained through linkage to electronic health records, and Cox regression was used to examine associations with dementia.

RESULTS

A total of 306 cases of dementia were recorded over a mean follow-up of 10 years. Baseline eGFR <60 was associated with a hazard ratio (HR) for dementia of 1.37 (95% CI 1.02, 1.85) in analysis adjusted for sociodemographic factors, hypertension, obesity, stroke, diabetes and cardiovascular disease/medication. Removing stroke cases at baseline and censoring them over the follow-up yielded an HR of 1.42 (95% CI 1.00, 2.00) for the association between CKD and dementia. Decline of eGFR ≥4 between 2007-2009 and 2012-2013 was associated with incidence of dementia over a 6.3 year mean follow-up (HR: 1.37; 95% CI 1.02, 1.85), with somewhat stronger associations when analyses were restricted to those with eGFR ≥60 in 2007-2009 (1.56; 95% CI: 1.12, 2.19).

CONCLUSION

Poor and declining kidney function in older adults is associated with a higher risk of dementia that is not attributable to stroke and persists after accounting for major cardiometabolic conditions.

Comorbidity in chronic kidney disease: a large cross-sectional study of prevalence in Scottish primary care

BACKGROUND

Chronic kidney disease (CKD) is commonly comorbid with hypertension, diabetes, and cardiovascular disease (CVD). However, the extent of comorbidity in CKD across a range of concordant (shared pathophysiology and/or treatment) conditions and discordant (unrelated pathophysiology and/or different or contradictory treatment) conditions is not well documented.

AIM

To ascertain the prevalence of comorbidity, across 39 physical and mental health comorbidities, in adults with CKD in a large, nationally representative primary care population.

DESIGN AND SETTING

Cross-sectional analysis of a primary care dataset representing 1 274 374 adults in Scotland.

METHOD

This study was a secondary analysis of general practice electronic medical record data using binary logistic regression models adjusted for age, sex, and socioeconomic status. Data of adults aged ≥25 years and 40 long-term conditions were used.

RESULTS

A total of 98.2% of adults with CKD had at least one comorbidity, versus 51.8% in controls. After adjustment for age, sex, and deprivation, people with CKD were more likely to have 1 (adjusted odds ratio [aOR] 6.5, 95% confidence interval [CI] = 6.0 to 7.1), 2-3 (aOR 15.2, 95% CI = 14.0 to 16.5), 4-6 (odds ratio [OR] 26.6, 95% CI = 24.4 to 28.9), and ≥7 other conditions (OR 41.9, 95% CI = 38.3 to 45.8). Furthermore, all concordant (seven out of seven), the majority of discordant physical health conditions (17 out of 24), and mental health conditions (six out of eight) had statistically significant positive associations with CKD after adjustment.

CONCLUSION

Chronic kidney disease is associated with extreme comorbidity across a wide range of mental and physical conditions. Routine care for people with CKD should include recognition and management of comorbidities, and clinical guidelines should support clinicians to do this.

Life course socioeconomic position and body composition in adulthood: a systematic review and narrative synthesis

INTRODUCTION

Multiple systematic reviews have investigated the relation between socioeconomic position (SEP) and body mass index (BMI) throughout the life course. However, BMI does not capture quantity and distribution of fat and muscle, which are better indicators of obesity than BMI, and have been independently linked to adverse health outcomes. Less is known about the relation between SEP and body composition, and the literature has not been reviewed. We therefore systematically reviewed the literature on the association between life course SEP and body composition in adulthood.

METHODS

A protocol was registered on PROSPERO (CRD42019119937), and the review followed PRISMA guidelines. An electronic search of three databases (MEDLINE, Embase Classic + Embase and SPORTDiscus) was conducted. Original studies in the English language were included that examine the association between any recognised measure of SEP at any age and body composition (fat mass, fat-free mass, ratio and distribution) in adulthood, measured using a direct technique, i.e., not an anthropometric measure. A narrative synthesis was conducted.

RESULTS

A total of 47 papers were included in the final review, none were from low-income countries (LICs). Greater advantage in childhood and adulthood was associated with lower fat levels in high-income countries (HICs). Associations in the opposite direction were found exclusively in middle-income countries (MICs). No studies in MICs reported associations for childhood SEP. For measures of lean mass, the majority of papers reported no association, or greater advantage in adulthood associated with higher lean mass, with little variation between HICs and MICs. Associations in HICs are more often observed in women than men.

CONCLUSION

The results indicate that fat measures follow similar patterns to those seen for BMI, and that women in HICs are more likely to experience inequalities in both fat and lean measures. Further research in LICs and MICs is needed.

Risk factors for decreased upper-limb muscle strength and its impact on survival in maintenance hemodialysis patients

PURPOSE

Protein-energy wasting, characterized by decreased muscle mass, is one of the strongest predictors of mortality in patients on maintenance hemodialysis (MHD). As people get older, their muscle strength usually declines faster than muscle mass. However, the association between lower-limb muscle strength and all-cause mortality remains unclear. We aimed to evaluate risk factors for decreased upper-limb muscle strength in MHD patients and its impact on patient survival.

METHODS

The cross-sectional part of the study included 174 MHD patients. Subsequently, they were followed up for 52 weeks. Biceps muscle strength, anthropometry, body composition, dietary intake, daily steps, and biochemical indicators of malnutrition and inflammation were evaluated. Risk factors for muscle weakness were screened by multiple linear regression analysis, and patient survival was analyzed by Kaplan-Merier and Cox multivariate analysis.

RESULTS

The 174 MHD patients (93 men; 63.05 ± 12.29 years) were classified as a young (< 65 years, n = 97) group and an elderly group (≥ 65 years, n = 77). Gender, daily steps, muscle mass, 25(OH)D level and IL-6 in young group, and muscle mass, 25(OH)D, daily steps, and NT-proBNP in elderly group were associated with the decreased biceps muscle strength. The survival rate in high muscle strength group was significantly higher than that in low muscle strength group (P = 0.002). The association between low muscle strength and high mortality risk remained strong in the fully adjusted model.

CONCLUSION

Risk factors of muscle weakness were different between young and elderly MHD patients. There was a strong correlation between strong biceps muscle strength and high patient survival.

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.

Chronic kidney disease and socio-economic status: a cross sectional study

Objective: This cross-sectional study investigated the relationship between individual-level markers of disadvantage, renal function and cardio-metabolic risk within an Indigenous population characterised by a heavy burden of chronic kidney disease and disadvantage.Design: Using data from 20 Indigenous communities across Australia, an aggregate socio-economic status (SES) score was created from individual-level socio-economic variables reported by participants. Logistic regression was used to assess the association of individual-level socio-economic variables and the SES score with kidney function (an estimated glomerular function rate (eGFR) cut-point of <60 ml/min/1.73 m²) as well as clinical indicators of cardio-metabolic risk.Results: The combination of lower education and unemployment was associated with poorer kidney function and higher cardio-metabolic risk factors. Regression models adjusted for age and gender showed that an eGFR < 60 ml/min/1.73 m² was associated with a low socio-economic score (lowest vs. highest 3.24 [95% CI 1.43-6.97]), remote living (remote vs. highly to moderately accessible 3.24 [95% CI 1.28-8.23]), renting (renting vs. owning/being purchased 5.76[95% CI 1.91-17.33]), unemployment (unemployed vs employed 2.85 [95% CI 1.31-6.19]) and receiving welfare (welfare vs. salary 2.49 [95% CI 1.42-4.37]). A higher aggregate socio-economic score was inversely associated with an eGFR < 60 ml/min/1.73 m² (0.75 [95% CI 063-0.89]).Conclusion: This study extends upon our understanding of associations between area-level markers of disadvantage and burden of end stage kidney disease amongst Indigenous populations to a detailed analysis of a range of well-characterised individual-level factors such as overall low socio-economic status, remote living, renting, unemployment and welfare. With the increasing burden of end-stage kidney disease amongst Indigenous people, the underlying socio-economic conditions and social and cultural determinants of health need to be understood at an individual as well as community-level, to develop, implement, target and sustain interventions.

Socioeconomic status and risk of kidney dysfunction: the Atherosclerosis Risk in Communities study

Background

There is strong evidence of an association between socioeconomic status (SES) and end-stage renal disease (ESRD). However, the association of SES with the risk of chronic kidney disease (CKD) and the rate of change in kidney function is unclear.

Methods

A cohort of 14 086 participants with an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 at baseline in the Atherosclerosis Risk in Communities study (1987–89) were studied. The association of annual household income, educational attainment and neighborhood deprivation with incident ESRD, incident CKD and change in eGFR using four measurements over ∼23 years was assessed.

Results

A total of 432 participants developed ESRD and 3510 developed CKD over a median follow-up time of ∼23 years. After adjustment for demographics and baseline eGFR, the hazard ratio (HR) for incident ESRD compared with the high-income group was 1.56 [95% confidence interval (CI) 1.22–1.99 in the medium-income group and 2.30 (95% CI 1.75–3.02) in the low-income group (P-trend < 0.001), and for CKD was 1.10 (95% CI 1.01–1.20) in the medium-income group and 1.30 (95% CI 1.17–1.44) in the low-income group (P-trend < 0.001). After full adjustments, the HR for ESRD was 1.33 (95% CI 1.03–1.70) in the medium-income group and 1.50 (95% CI 1.14–1.98) in the low-income group (P-trend = 0.003) and for CKD was 1.01 (95% CI 0.92–1.10) in the medium-income group and 1.04 (95% CI 0.93–1.16) in the low-income group (P-trend = 0.50). The eGFR decline was 5% and 15% steeper in the medium- and low-income groups, respectively, after full adjustment (P-trend < 0.001). Results were similar, with lower educational attainment and higher neighborhood deprivation being associated with adverse outcomes.

Conclusions

SES (annual household income, educational attainment or neighborhood deprivation) was associated not only with ESRD risk but also with eGFR decline, although the association with CKD appeared weaker.

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.

Multiple socioeconomic deprivation and impact on survival in patients with primary glomerulonephritis

Background: The impact of multiple socio-economic deprivation on patient outcomes in primary renal diseases is unknown. We aimed to assess whether risk of death or requiring renal replacement therapy (RRT) in patients with primary glomerulonephritis (GN) was higher in patients living in an area of multiple socio-economic deprivation.

Methods: Patients undergoing native renal biopsy between 2000 and 2014 were identified. Baseline demographics, postcode at time of biopsy, follow-up blood pressure, proteinuria and time to death or RRT were recorded. The Scottish Index of Multiple Deprivation (SIMD) is a multidimensional model used to measure deprivation based on postcode. Using SIMD, patients were separated into tertiles of deprivation.

Results: A total of 797 patients were included, 64.2% were male with mean age of 54.1 (standard deviation 17.0) years. Median follow-up was 6.3 (interquartile range 3.7–9.4) years during which 174 patients required RRT and 185 patients died. Patients in the most deprived tertile of deprivation were significantly more likely to die than those in the least deprived tertile [hazard ratio (HR) 2.2, P  <  0.001], independent of age, baseline serum creatinine and blood pressure. They were not more likely to require RRT (P  =  0.22). The increased mortality risk in the most deprived tertile was not uniform across primary renal diseases, with the association being most marked in focal segmental glomerulosclerosis (HR 7.4) and IgA nephropathy (HR 2.7) and absent in membranous nephropathy.

Conclusion: We have demonstrated a significant independent 2-fold increased risk of death in patients with primary GN who live in an area of multiple socio-economic deprivation at the time of diagnosis as compared with those living in less deprived areas.

High-Normal Estimated Glomerular Filtration Rate in Early-Onset Preeclamptic Women 10 Years Postpartum

Women with a history of preeclampsia have a 5- to 12-fold increased risk to develop end-stage kidney disease. Previous observations in small cohorts suggest that former preeclamptic (fPE) women have subtle abnormalities in renal hemodynamics and renal function, which might predispose them to renal failure in later life. In this study, we analyzed renal function in a cross-sectional cohort consisting of former early-onset preeclamptic (fPE, n=339) and former healthy pregnant women (fHP, n=332), overall with a mean age of 39 years at 10 years postpartum. Estimated glomerular filtration rate (eGFR), assessed by the modification of diet in renal disease (MDRD) and chronic kidney disease–epidemiology (CKD-epi) equations, and urinary protein:creatinine ratios were assessed 10 years postpartum. Median MDRD and CKD-epi eGFR did not significantly differ between fHP and fPE groups, whereas a comparison of distribution of eGFR revealed a shift toward a high-normal MDRD eGFR in the fPE group (χ 2 , P =0.02) with the same trend for CKD-epi eGFR (χ 2 , P =0.18). The odds ratio for fPE women having MDRD eGFR >110 mL/min per 1.73 m 2 was 1.6 (1.1–2.4). In addition, the median urinary protein:creatinine ratio was slightly higher in fPE (8.5 versus 7.1 mg/mmol; P <0.01) and correlated positively with both MDRD and CKD-epi eGFR in fPE women. No increased incidence of CKD in fPE women was observed. In conclusion, we demonstrate subtle changes in renal function in former early-onset preeclamptic women 10 years postpartum, characterized by a high-normal eGFR and a slightly higher protein excretion. Whether these subtle differences predispose to or predict long-term renal function loss in fPE women remains to be investigated.

Clinical Trial Registration—

URL: http://www.trialregister.nl . Unique identifier: NTR2668.

Mendelian Randomisation study of the influence of eGFR on coronary heart disease

Impaired kidney function, as measured by reduced estimated glomerular filtration rate (eGFR), has been associated with increased risk of coronary heart disease (CHD) in observational studies, but it is unclear whether this association is causal or the result of confounding or reverse causation. In this study we applied Mendelian randomisation analysis using 17 genetic variants previously associated with eGFR to investigate the causal role of kidney function on CHD. We used 13,145 participants from the UCL-LSHTM-Edinburgh-Bristol (UCLEB) Consortium and 194,427 participants from the Coronary ARtery DIsease Genome-wide Replication and Meta-analysis plus Coronary Artery Disease (CARDIoGRAMplusC4D) consortium. We observed significant association of an unweighted gene score with CHD risk (odds ratio = 0.983 per additional eGFR-increasing allele, 95% CI = 0.970–0.996, p = 0.008). However, using weights calculated from UCLEB, the gene score was not associated with disease risk (p = 0.11). These conflicting results could be explained by a single SNP, rs653178, which was not associated with eGFR in the UCLEB sample, but has known pleiotropic effects that prevent us from drawing a causal conclusion. The observational association between low eGFR and increased CHD risk was not explained by potential confounders, and there was no evidence of reverse causation, therefore leaving the remaining unexplained association as an open question.

Serum phosphate and social deprivation independently predict all-cause mortality in chronic kidney disease

Background

Hyperphosphataemia is linked to cardiovascular disease and mortality in chronic kidney disease (CKD). Outcome in CKD is also affected by socioeconomic status. The objective of this study was to assess the associations between serum phosphate, multiple deprivation and outcome in CKD patients.

Methods

All adult patients currently not on renal replacement therapy (RRT), with first time attendance to the renal outpatient clinics in the Glasgow area between July 2010 and June 2014, were included in this prospective study. Area socioeconomic status was assessed as quintiles of the Scottish Index of Multiple Deprivation (SIMD). Outcomes were all-cause and cardiovascular mortality and commencement of RRT.

Results

The cohort included 2950 patients with a median (interquartile range) age 67.6 (53.6–76.9) years. Median (interquartile range) eGFR was 38.1 (26.3–63.5) ml/min/1.73 m², mean (±standard deviation) phosphate was 1.13 (±0.24) mmol/L and 31.6 % belonged to the most deprived quintile (SIMD quintile I). During follow-up 375 patients died and 98 commenced RRT. Phosphate ≥1.50 mmol/L was associated with all-cause (hazard ratio (HR) 2.51; 95 % confidence interval (CI) 1.63-3.89) and cardiovascular (HR 5.05; 95 % CI 1.90–13.46) mortality when compared to phosphate 0.90–1.09 mmol/L in multivariable analyses. SIMD quintile I was independently associated with all-cause mortality. Phosphate did not weaken the association between deprivation index and mortality, and there was no interaction between phosphate and SIMD quintiles. Neither phosphate nor SIMD predicted commencement of RRT.

Conclusions

Multiple deprivation and serum phosphate were strong, independent predictors of all-cause mortality in CKD and showed no interaction. Phosphate also predicted cardiovascular mortality. The results suggest that phosphate lowering should be pursued regardless of socioeconomic status.

Chronic kidney disease among adult participants of the ELSA-Brasil cohort: association with race and socioeconomic position

BACKGROUND

There is increased interest in understanding why chronic kidney disease (CKD) rates vary across races and socioeconomic groups. We investigated the distribution of estimated glomerular filtration rate (eGFR), urinary albumin-creatinine ratio (ACR) and CKD according to these factors in Brazilian adults.

METHODS

Using baseline data (2008-2010) of 14,636 public sector employees (35-74 years) enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA)-Brasil multicentre cohort, we estimated the prevalence of CKD by sex, age, race and socioeconomic factors. CKD was defined as ACR ≥ 30 mg/g and/or eGFR < 60 mL/min/1.73 m(2). GFR was estimated by CKD epidemiology collaboration without correction for race. We used logistic regression to estimate the association of race and socioeconomic position (education, income, social class and occupational nature) with CKD after adjusting for sex, age and several health-related factors.

RESULTS

The prevalence of high ACR or low eGFR, in isolation and combined, increased with age, and was higher in individuals with lower socioeconomic position and among black individuals and indigenous individuals. The overall prevalence of CKD was 8.9%. After full adjustments, it was similar in men and women (OR=0.90; 95% CI 0.79 to 1.02) and increased with age (OR=1.07; 95% CI 1.06 to 1.08). Compared to white individuals, black individuals (OR=1.23; 95% CI 1.03 to 1.47), 'pardos' (OR=1.16; 95% CI 1.00 to 1.35) and Indigenous (OR=1.72; 95% CI 1.07 to 2.76) people had higher odds for CKD. Having high school (OR=1.15; 95% CI 1.00 to 1.34) or elementary education (OR=1.23; 95% CI 1.03 to 1.47) increased the odds for CKD compared to those having a university degree.

CONCLUSIONS

There were marked discrepancies in the increases in reduced eGFR and high ACR with age and race. The higher prevalences of CKD in individuals with lower educational status and in non-whites were not explained by differences in health-related factors.

Socioeconomic disparities in chronic kidney disease: a systematic review and meta-analysis

CONTEXT

Evidence on the strength of the association between low SES and chronic kidney disease (CKD; measured by low estimated glomerular filtration rate [eGFR], high albuminuria, low eGFR/high albuminuria, and renal failure) is scattered and sometimes conflicting. Therefore, a systematic review and meta-analysis was performed to summarize the strength of the associations between SES and CKD and identify study-level characteristics related to this association.

EVIDENCE ACQUISITION

Studies published through January 2013 in MEDLINE and Embase were searched. From 35 studies that met the inclusion criteria, association estimates were pooled per CKD measure in the meta-analysis (performed between 2013 and 2014). Meta-regression analysis was used to identify study-level characteristics related to the strength of the SES-CKD association.

EVIDENCE SYNTHESIS

Low SES was associated with low eGFR (OR=1.41, 95% CI=1.21, 1.62), high albuminuria (OR=1.52, 95% CI=1.22, 1.82), low eGFR/high albuminuria (OR=1.38, 95% CI=1.03, 1.74), and renal failure (OR=1.55, 95% CI=1.40, 1.71). Differences in SES measures across studies were not related to the strength of associations between low SES and any of the CKD measures (low GFR, p=0.63; high albuminuria, p=0.29; low eGFR/high albuminuria, p=0.54; renal failure, p=0.31). Variations in the strength of associations were related to the level of covariate adjustment for low eGFR (p<0.001) and high albuminuria (p<0.001).

CONCLUSIONS

Socioeconomic disparities in CKD were fairly strong, irrespective of how SES was measured. Variations in the strength of the associations were related to the level of covariate adjustment, particularly for low eGFR and high albuminuria.

Mediators of the association between low socioeconomic status and chronic kidney disease in the United States

Using data collected from 9,823 participants in the 2007-2008 and 2009-2010 cycles of the National Health and Nutrition Examination Survey, we formally investigated potentially modifiable factors linking low socioeconomic status (SES) to chronic kidney disease (CKD) for their presence and magnitude of mediation. SES was defined using the poverty income ratio. The main outcome was CKD, defined as estimated glomerular filtration rate <60 mL/minute/1.73 m(2) (using the Chronic Kidney Disease Epidemiology Collaboration equation) and/or urinary albumin:creatinine ratio ≥30 mg/g. In mediation analyses, we tested the contributions of health-related behaviors (smoking, alcohol intake, diet, physical activity, and sedentary time), comorbid conditions (diabetes, hypertension, obesity, abdominal obesity, and hypercholesterolemia), and access to health care (health insurance and routine health-care visits) to this association. Except for sedentary time and diet, all examined health-related behaviors, comorbid conditions, and factors related to health-care access mediated the low SES-CKD association and contributed 20%, 32%, and 11%, respectively, to this association. In race/ethnicity-specific analyses, identified mediators tended to explain more of the association between low SES and CKD in non-Hispanic blacks than in other racial/ethnic groups. In conclusion, potentially modifiable factors like health-related behaviors, comorbid conditions, and health-care access contribute substantially to the association between low SES and CKD in the United States, especially among non-Hispanic blacks.

Socio-economic status influences chronic kidney disease prevalence in primary care: a community-based cross-sectional analysis

BACKGROUND

Primary care chronic kidney disease (CKD) registers report widely varying prevalence within the UK. We examined the effects of laboratory ascertainment and adjusting for practice-level variables on the variation in CKD prevalence. We carried out an Ayrshire-wide laboratory database analysis of primary care practices (PCPs).

METHODS

We analysed 54 PCPs with 313 639 registered patients aged ≥ 18. All patients with a low estimated glomerular filtration rate (<60 mL/min/1.73 m(2)) had their serum creatinine values extracted from 1st January 2009 to 31st March 2012. Individuals with CKD stage 3-5 were identified with an algorithm that confirmed chronicity. These data were linked to PCP attributes from Information Services Division, Scotland. Using laboratory-ascertained CKD prevalence, we examined whether adjusting for practice-level factors [socio-economic status (SES), rurality and patients to general practitioner ratio (PGR)] and patient-level factors (age, gender) explained some of the observed variation among PCPs. Individual and combined hierarchical multilinear regression models were used.

RESULTS

Eighteen thousand two hundred and eighty-five (5.8%) had CKD stage 3-5 on 31 March 2011. SES, rurality and PGR predicted 39% (F(3,50) = 12.37, P < 0.001) of the variation in prevalence with SES exerting the most influence (25%). With the stepwise addition of explanatory variables, variation between practices fell from 3.9-fold using PCP register prevalence to laboratory ascertained (3.1-fold variation), with age and gender adjustment (further fall to 2.1-fold), and lastly to 1.8-fold variation with adjustment for SES. Funnel plots using these adjustments reduced the number of outliers outside of 3 SD from 15 to 7 to 6, and outliers between 2 and 3 SD by 16 to 13 to 5.

CONCLUSIONS

Laboratory ascertainment is practicable, reduces variation and facilitates benchmarking. PCP attributes other than age and gender impact on prevalence. Over a third of variation in CKD prevalence among PCPs can be explained by rurality, PGR and especially SES even after age and gender stratification.

Socioeconomic position across life and body composition in early old age: findings from a British birth cohort study

BACKGROUND

Previous studies have reported associations between lower lifetime socioeconomic position (SEP) and higher body mass index in adulthood, but few have examined associations with direct measures of fat and lean mass which are likely to have independent roles in health and physical functioning.

METHODS

We examined associations of SEP across life with dual-energy X-ray absorptiometry measures of fat and lean mass at 60-64 years using data from a total of 1558 men and women participating in the Medical Research Council (MRC) National Survey of Health and Development. We also examined whether associations of childhood SEP with fat and lean mass were explained by preadulthood weight gain (birth weight, 0-7 and 7-20 years) and adult SEP.

RESULTS

Lower SEP across life was associated with higher fat mass and higher android to gynoid fat mass ratio. For example, the mean difference in fat mass index comparing the lowest with the highest paternal occupational class at 4 years (slope index of inequality) was 1.04 kg/m(1.2) in men (95% CI 0.09 to 1.99) and 2.61 in women (1.34 to 3.89), equivalent to a 8.6% and 16.1% difference, respectively. After adjustment for fat mass, lower SEP across life was associated with lower lean mass in women, while only contemporaneous household income was associated in men. Associations between childhood SEP and outcomes were partly explained by preadulthood weight gain and adult SEP.

CONCLUSIONS

This study identified lifetime socioeconomic patterning of fat and lean mass in early old age. This is likely to have important implications and may partly explain socioeconomic inequalities in health and physical functioning.

Chronic kidney disease, albuminuria and socioeconomic status in the Health Surveys for England 2009 and 2010

BACKGROUND

Renal replacement therapy rates are inversely related to socioeconomic status (SES) in developed countries. The relationship between chronic kidney disease (CKD) and SES is less clear. This study examined the relationships between SES and CKD and albuminuria in England.

METHODS

Data from the Health Survey for England 2009 and 2010 were combined. The prevalence of CKD 3-5 and albuminuria was calculated, and logistic regression used to determine their association with five individual-level measures and one area-level measure of SES.

RESULTS

The prevalence of CKD 3-5 was 5.2% and albuminuria 8.0%. Age-sex-adjusted CKD 3-5 was associated with lack of qualifications [odds ratio (OR) 2.27 (95% confidence interval 1.40-3.69)], low income [OR 1.50 (1.02-2.21)] and renting tenure [OR 1.36 (1.01-1.84)]. Only tenure remained significant in fully adjusted models suggesting that co-variables were on the causal pathway. Albuminuria remained associated with several SES measures on full adjustment: low income [OR 1.55 (1.14-2.11)], no vehicle [OR 1.38 (1.05-1.81)], renting [OR 1.31 [1.03-1.67)] and most deprived area-level quintile [OR 1.55 (1.07-2.25)].

CONCLUSIONS

CKD 3-5 and albuminuria were associated with low SES using several measures. For albuminuria this was not explained by known measured causal factors.

Prevalence and associated factors of microalbuminuria in Chinese individuals without diabetes: cross-sectional study

OBJECTIVE

To investigate the prevalence of microalbuminuria (MAU) among Chinese individuals without diabetes and the relationship between MAU and metabolic factors, individual socioeconomic status (SES), and regional economic development level.

DESIGN

Cross-sectional study of prevalence of MAU.

SETTING

152 urban street districts and 112 rural villages from northeast, north, east, south central, northwest and southwest China.

PARTICIPANTS

46 239 participants were recruited using a multistage stratified sampling design from 2007 to 2008. A total of 41 290 participants without diabetes determined by oral glucose tolerance test were included in the present study. Urine albumin/creatinine ratio results of 35 430 individuals were available.

PRIMARY AND SECONDARY OUTCOME MEASURES

Positive detection of MAU was determined using an ACR of 22.1-299.9 mg/g in men 30.9-299.9 mg/g in women.

RESULTS

The prevalence of MAU in men was 22.4% and 24.5% in women. In developed, intermediate-developed and under-developed areas, the prevalence of MAU in men was 20.7%, 21.9% and 32.5%, respectively; in women the prevalence was 19.6%, 26.0% and 29.5%, respectively. The prevalence of MAU increased as the number of metabolic disorders present increased, and as the number of lower SES components increased (farmer, below university education level and low income). Prevalence of MAU in developed and intermediate developed areas had adjusted risk ratios of 0.52 (95% CI 0.42 to 0.60) and 0.65 (95% CI 0.57 to 0.76), respectively. Multivariate logistic analyses demonstrated MAU was strongly associated with older age, high-blood pressure, higher blood glucose low education level, low occupational level and residence in under-developed region.

CONCLUSIONS

Several factors had independent correlations to MAU in China: older age, metabolic abnormalities, lower SES level and living in economically under-developed areas, which encourage the development of strategies to lower the risk for MAU in these susceptible populations.

The incidence of biopsy-proven IgA nephropathy is associated with multiple socioeconomic deprivation

Chronic kidney disease is more common in areas of socioeconomic deprivation, but the relationship with the incidence and diagnosis of biopsy-proven renal disease is unknown. In order to study this, all consecutive adult patients undergoing renal biopsy in West and Central Scotland over an 11-year period were prospectively analyzed for demographics, indication, and histologic diagnosis. Using the Scottish Index of Multiple Deprivation, 1555 eligible patients were separated into quintiles of socioeconomic deprivation according to postcode. Patients in the most deprived quintile were significantly more likely to undergo biopsy compared with patients from less deprived areas (109.5 compared to 95.9 per million population/year). Biopsy indications were significantly more likely to be nephrotic syndrome, or significant proteinuria without renal impairment. Patients in the most deprived quintile were significantly more likely to have glomerulonephritis. There was a significant twofold increase in the diagnosis of IgA nephropathy in the patients residing in the most compared with the least deprived postcodes not explained by the demographics of the underlying population. Thus, patients from areas of socioeconomic deprivation in West and Central Scotland are significantly more likely to undergo native renal biopsy and have a higher prevalence of IgA nephropathy.

Socioeconomic measures and CKD in the United States and The Netherlands

BACKGROUND AND OBJECTIVES

According to the cost of health care utilization systems, there may be regional differences in the relative strength of association of income and education-based socioeconomic status measures with CKD. This study investigated the relative strength of the association of income and education with CKD in a United States and a Dutch population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This cross-sectional study examined individuals who participated in the 1999-2002 National Health and Nutritional Examination Survey (NHANES) and in Prevention of Renal and Vascular End-stage Disease (PREVEND 1997-1998), general population-based cohorts in the United States and The Netherlands, respectively. The main outcome was CKD, defined as estimated GFR <60 ml/min per 1.73 m(2) (using creatinine) or albuminuria ≥ 30 mg/24 hours or albumin-to-creatinine ratio ≥ 30 mg/g.

RESULTS

In NHANES (n=6428), income was strongly associated with CKD (adjusted odds ratio, 2.34 [95% confidence interval (CI), 1.68 to 3.27]; P for trend<0.001) but education was not (adjusted odds ratio, 1.62 [95% CI, 0.87 to 2.25]; P for trend=0.05]. In contrast, in PREVEND (n=7983), low income was weakly associated with CKD whereas low education had a strong association. The fit of the logistic regression model estimating association of income and education with CKD was significantly improved only after income was added in NHANES (P<0.001) and education was added in PREVEND (P=0.01). Sensitivity analyses that used other CKD-defining variables and restricted analyses to participants <65 years of age resulted in similar findings.

CONCLUSION

In the United States, where access to health care is traditionally income dependent, income appeared more strongly associated with CKD than in The Netherlands, where education showed a stronger association.

Early life influences kidney function at age 63-64 years, but so does adult body size: results from the newcastle thousand families birth cohort

BACKGROUND

It is suggested that impaired fetal growth can affect kidney development, resulting in fewer glomeruli being formed and reduced kidney function later in life. The aim of this study was to investigate early life variables in relation to adult kidney function, and compare these to the influence of later life variables.

METHODS

Detailed information was collected prospectively regarding 1,142 babies, born in 1947 in Newcastle upon Tyne. At the age of 63-64 years, 335 participants had serum creatinine successfully measured and completed a lifestyle questionnaire. These measurements were used to calculate their estimated glomerular filtration rate (eGFR).

RESULTS

Body mass index (BMI) and being female were significantly negatively associated with eGFR. Birth weight was significantly positively associated with eGFR. In sex-specific analyses, BMI and cigarette smoking remained significant for males (n = 154), with a near significant association for birth weight, whereas none of the variables remained significant for females (n = 181).

CONCLUSIONS

The findings suggest that sex, size at birth and BMI may be important variables influencing adult kidney function. However, as only a small amount of variance in eGFR was explained by these variables, additional longitudinal studies would be beneficial for assessing lifecourse influences on kidney function.

The natural history of, and risk factors for, progressive chronic kidney disease (CKD): the Renal Impairment in Secondary care (RIISC) study; rationale and protocol

BACKGROUND

Chronic kidney disease (CKD) affects up to 16% of the adult population and is associated with significant morbidity and mortality. People at highest risk from progressive CKD are defined by a sustained decline in estimated glomerular filtration rate (eGFR) and/or the presence of significant albuminuria/proteinuria and/or more advanced CKD. Accurate mapping of the bio-clinical determinants of this group will enable improved risk stratification and direct the development of better targeted management for people with CKD.

METHODS/DESIGN

The Renal Impairment In Secondary Care study is a prospective, observational cohort study, patients with CKD 4 and 5 or CKD 3 and either accelerated progression and/or proteinuria who are managed in secondary care are eligible to participate. Participants undergo a detailed bio-clinical assessment that includes measures of vascular health, periodontal health, quality of life and socio-economic status, clinical assessment and collection of samples for biomarker analysis. The assessments take place at baseline, and at six, 18, 36, 60 and 120 months; the outcomes of interest include cardiovascular events, progression to end stage kidney disease and death.

DISCUSSION

The determinants of progression of chronic kidney disease are not fully understood though there are a number of proposed risk factors for progression (both traditional and novel). This study will provide a detailed bio-clinical phenotype of patients with high-risk chronic kidney disease (high risk of both progression and cardiovascular events) and will repeatedly assess them over a prolonged follow up period. Recruitment commenced in Autumn 2010 and will provide many outputs that will add to the evidence base for progressive chronic kidney disease.

Audit-based education lowers systolic blood pressure in chronic kidney disease: the Quality Improvement in CKD (QICKD) trial results

Strict control of systolic blood pressure is known to slow progression of chronic kidney disease (CKD). Here we compared audit-based education (ABE) to guidelines and prompts or usual practice in lowering systolic blood pressure in people with CKD. This 2-year cluster randomized trial included 93 volunteer general practices randomized into three arms with 30 ABE practices, 32 with guidelines and prompts, and 31 usual practices. An intervention effect on the primary outcome, systolic blood pressure, was calculated using a multilevel model to predict changes after the intervention. The prevalence of CKD was 7.29% (41,183 of 565,016 patients) with all cardiovascular comorbidities more common in those with CKD. Our models showed that the systolic blood pressure was significantly lowered by 2.41 mm Hg (CI 0.59-4.29 mm Hg), in the ABE practices with an odds ratio of achieving at least a 5 mm Hg reduction in systolic blood pressure of 1.24 (CI 1.05-1.45). Practices exposed to guidelines and prompts produced no significant change compared to usual practice. Male gender, ABE, ischemic heart disease, and congestive heart failure were independently associated with a greater lowering of systolic blood pressure but the converse applied to hypertension and age over 75 years. There were no reports of harm. Thus, individuals receiving ABE are more likely to achieve a lower blood pressure than those receiving only usual practice. The findings should be interpreted with caution due to the wide confidence intervals.

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.

Influence of race, ethnicity and socioeconomic status on kidney disease

Low socioeconomic status (SES) influences disease incidence and contributes to poor health outcomes throughout an individual's life course across a wide range of populations. Low SES is associated with increased incidence of chronic kidney disease, progression to end-stage renal disease, inadequate dialysis treatment, reduced access to kidney transplantation, and poor health outcomes. Similarly, racial and ethnic disparities, which in the USA are strongly associated with lower SES, are independently associated with poor health outcomes. In this Review, we discuss individual-level and group-level SES factors, and the concomitant role of race and ethnicity that are associated with and mediate the development of chronic kidney disease, progression to end-stage renal disease and access to treatment.

Overweight, obesity and intentional weight loss in chronic kidney disease: NHANES 1999-2006

Objective

Obesity and chronic kidney disease (CKD) have emerged as major public health problems. We aimed to examine: a) lifestyle and behavioral factors, b) factors related to pursuing weight loss, and c) weight loss modalities pursued by CKD and non-CKD individuals who are overweight and obese.

Methods

Cross-sectional analysis of 10,971 overweight and obese adult participants in the National Health and Nutrition Examination Surveys conducted between 1999-2006. We examined the differences in lifestyle and behavioral factors between CKD and non-CKD participants and factors associated with pursuing weight loss using survey regression models.

Results

The total daily energy intake of the CKD population was lower than the non-CKD group (1987 kcal/day vs. 2063 kcal/day, p=0.02) even after adjusting for relevant covariates. However, the percentage of energy derived from protein was similar between the groups. Sixty-six percent of the CKD population did not meet the minimum recommended leisure time physical activity goals compared to 57% among non-CKD (p<0.001). Fifty percent of CKD participants pursued weight loss (vs. 55% of non-CKD individuals, p=0.01), but the presence of CKD was not independently associated with the pursuit of weight loss in the multivariate model. Among participants pursuing weight loss, modalities including dietary interventions utilized by CKD and non-CKD participants were similar. Eight percent of CKD participants used medications to promote weight loss.

Conclusions

Among the overweight and obese population, lifestyle and behavioral factors related to obesity and weight loss are similar between CKD and non-CKD participants. Insufficient data exist on the beneficial effects of intentional weight loss in CKD and these data show that a significant proportion of the CKD population use diets that may have high protein content and medications to promote weight loss that may be harmful. Future clinical trials evaluating the efficacy and optimal modalities to treat obesity in the CKD population are warranted.