Geographic variation in CKD prevalence and ESRD incidence in the United States: results from the reasons for geographic and racial differences in stroke (REGARDS) study

COVID-19 and Kidney Disease (KD): A Retrospective Investigation in a Rural Southwestern Missouri Region Patient Population

BACKGROUND

Studies have linked pre-existing kidney disease (KD) to higher rates of mortality due to coronavirus disease 2019 (COVID-19) infection. In the rural Midwest, where KD is prevalent, the impact of COVID-19 has been significant in a population that includes many patients on Medicare or Medicaid.

METHODS

A retrospective cohort study was performed assessing patients with acute kidney injury (AKI), chronic kidney disease (CKD) and end stage renal disease (ESRD), with and without COVID-19. International Classification of Diseases 10^th Revision codes were submitted by physicians into Freeman Health System's Electronic Medical Records and gathered from April 2020 to January 2021. The data were analyzed and compared to determine whether the mortality rate in patients with varying stages of KD and COVID-19 was higher than the mortality rate in patients with KD alone, excluding variables such as sex and age.

RESULTS

The 95% confidence interval (CI) of the mortality rate of patients with COVID-19 and any degree of KD, encompassing both AKI and CKD, was between 30.21% and 37.63%. This metric was significantly higher than the 95% CI of COVID-19 infection (6.70%-9.96%, p<0.0001) or KD alone (10.89%-13.01%, p<0.0001). Within those with COVID-19 and KD, the highest rate of mortality was in patients with AKI (38.13% and 49.02%). There was not sufficient statistical support in our sample to assert that COVID-19 increased mortality in ESRD patients.

CONCLUSIONS

Based on our results, patients with KD and COVID-19 are at higher risk for mortality when compared to patients with KD alone. Further studies are warranted into individual comorbidities affecting KD patient outcomes with COVID-19.

Computational Analysis Reveals Distinctive Interaction of miRNAs with Target Genes in the Pathogenesis of Chronic Kidney Disease

The regulation of genes is crucial for maintaining a healthy intracellular environment, and any dysregulation of gene expression leads to several pathological complications. It is known that many diseases, including kidney diseases, are regulated by miRNAs. However, the data on the use of miRNAs as biomarkers for the diagnosis and treatment of chronic kidney disease (CKD) are not conclusive. The purpose of this study was to elucidate the potential of miRNAs as an efficient biomarker for the detection and treatment of CKD at its early stages. Gene expression profiling data were acquired from the Gene Expression Omnibus (GEO) and differentially expressed genes (DEGs) were identified. miRNAs directly associated with CKD were obtained from an extensive literature search. Network illustration of miRNAs and their projected target differentially expressed genes (tDEGs) was accomplished, followed by functional enrichment analysis. hsa-miR-1-3p, hsa-miR-206, hsa-miR-494 and hsa-miR-577 exhibited a strong association with CKD through the regulation of genes involved in signal transduction, cell proliferation, the regulation of transcription and apoptotic process. All these miRNAs have shown significant contributions to the inflammatory response and the processes which eventually lead to the pathogenesis of CKD. The in silico approach used in this research represents a comprehensive analysis of identified miRNAs and their target genes for the identification of molecular markers of disease processes. The outcomes of the study recommend further efforts for developing miRNA biomarkers set for the early diagnosis of CKD.

International Variability of Renal and Cardiovascular Outcomes and Mortality in Patients with Type 2 Diabetes Mellitus in Europe

INTRODUCTION

Type 2 diabetes and its complications represent a huge burden to public health. With this prospective, observational cohort study, we aimed to estimate and to compare the incidence rate (IR) of renal and cardiovascular outcomes and all-cause mortality in patients with type 2 diabetes in different European countries.

METHODS

The renal endpoint was a composite of a sustained decline in estimated GFR of at least 40%, a sustained increase in albuminuria of at least 30% including a transition in albuminuria class, progression to kidney failure with replacement therapy, or death from renal causes. The cardiovascular endpoint was a composite of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke.

RESULTS

3,131 participants from four European countries (Austria, Hungary, The Netherlands, and Scotland) with a median follow-up time of 4.4 years were included. IRs were adjusted for several risk factors including sex, age, estimated GFR, albuminuria, HbA1c, blood pressure, and duration of type 2 diabetes. Across countries, the adjusted IR for the renal endpoint was significantly higher in Hungary and Austria, and the adjusted IR for the cardiovascular endpoint was significantly higher in Scotland and Austria. All-cause mortality was significantly higher in Scotland compared to all other countries.

CONCLUSION

Our findings show how the longitudinal outcome of patients with type 2 diabetes varies significantly across European countries even after accounting for the distribution of underlying risk factors.

Twenty years of real-world data to estimate chronic kidney disease prevalence and staging in an unselected population

Chronic kidney disease (CKD) represents a global public health burden, but its true prevalence is not fully characterized in the majority of countries. We studied the CKD prevalence in adult users of the primary, secondary and tertiary healthcare units of an integrated health region in northern Portugal (n = 136 993; representing ∼90% of the region's adult population). Of these, 45 983 (33.6%) had at least two estimated glomerular filtration rate (eGFR) assessments and 30 534 (22.2%) had at least two urinary albumin:creatinine ratio (UACR) assessments separated by at least 3 months. CKD was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines as a persistent decrease in eGFR (<60 ml/min/1.73 m²) and/or an increase in UACR (≥30 mg/g). The estimated overall prevalence of CKD was 9.8% and was higher in females (5.5%) than males (4.2%). From these, it was possible to stratify 4.7% according to KDIGO guidelines. The prevalence of CKD was higher in older patients (especially in patients >70 years old) and in patients with comorbidities. This is the first real-world-based study to characterize CKD prevalence in a large, unselected Portuguese population. It probably provides the nearest estimate of the true CKD prevalence and may help healthcare providers to guide CKD-related policies and strategies focused on prevention and on the improvement of cardiovascular disease and other outcomes.

Health Disparities in Autosomal Dominant Polycystic Kidney Disease (ADPKD) in the United States

BACKGROUND AND OBJECTIVES

Autosomal dominant polycystic kidney disease (ADPKD) occurs at conception and is often diagnosed decades prior to kidney failure. Nephrology care and transplantation access should be independent of race and ethnicity. However, institutional racism and barriers to health care may affect patient outcomes in ADPKD. We sought to ascertain the effect of health disparities on outcomes in ADPKD by examining age at onset of kidney failure and access to preemptive transplantation and transplantation after dialysis initiation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Retrospective cohort analyses of adults with ADPKD in the United States Renal Data System from January 2000 to June 2018 were merged to US Census income data and evaluated by self-reported race and ethnicity. Age at kidney failure was analyzed in a linear model, and transplant rates before and after dialysis initiation were analyzed in logistic and proportional hazards models in Black and Hispanic patients with ADPKD compared with White patients with ADPKD.

RESULTS

A total of 41,485 patients with ADPKD were followed for a median of 25 (interquartile range, 5-54) months. Mean age was 56±12 years; 46% were women, 13% were Black, and 10% were Hispanic. Mean ages at kidney failure were 55±13, 53±12, and 57±12 years for Black patients, Hispanic patients, and White patients, respectively. Odds ratios for preemptive transplant were 0.33 (95% confidence interval, 0.29 to 0.38) for Black patients and 0.50 (95% confidence interval, 0.44 to 0.56) for Hispanic patients compared with White patients. Transplant after dialysis initiation was 0.61 (95% confidence interval, 0.58 to 0.64) for Black patients and 0.78 (95% confidence interval, 0.74 to 0.83) for Hispanic patients.

CONCLUSIONS

Black and Hispanic patients with ADPKD reach kidney failure earlier and are less likely to receive a kidney transplant preemptively and after initiating dialysis compared with White patients with ADPKD.

The Impact of Chronic Medical Conditions on Mortality in Acute Respiratory Distress Syndrome

PURPOSE

To examine the impact of chronic comorbidities on mortality in Acute Respiratory Distress Syndrome (ARDS).

MATERIALS AND METHODS

Retrospective cohort study of adults with ARDS (ICD-10-CM code J80) from the National Inpatient Sample between January, 2016 and December, 2018. For the primary outcome of mortality, we conducted weighted logistic regression adjusting for factors identified on univariate analysis as potentially significant or differing between the two groups at baseline. We used negative binomial regression adjusting for the same comorbidities to identify risk factors for longer length of stay (LOS) among ARDS survivors.

RESULTS

After exclusions, 1046 records were analyzed (3355 ARDS survivors and 1875 non-survivors.) The comorbidities examined included hypertension, diabetes mellitus, obesity, hypothyroidism, alcohol and drug use, chronic kidney disease (CKD), cardiovascular disease, chronic liver disease, chronic pulmonary disease and malignancy. In multivariate analysis, we found that malignancy (OR 2.26, 95% CI 1.84-2.78, p < 0.001), cardiovascular disease (OR 1.54, 95% CI 1.23-1.92, p < 0.001), and CKD (OR 1.75, 95% CI 1.22-2.50, p  =  0.002) increased the risk of death. In interaction analyses, cardiovascular disease combined with either malignancy or CKD conferred higher odds of death compared to either risk factor alone.

CONCLUSIONS

The comorbidity of malignancy confers the most reliable risk of poor outcomes in ARDS with higher odds of hospital death and a simultaneous association with longer hospital LOS among survivors.

County-Level Characteristics Associated with Variation in ESKD Mortality in the United States, 2010-2018

Background

Geographic and neighborhood-level factors, such as poverty and education, have been associated with an increased risk for incident ESKD, likelihood of receiving pre-ESKD care, and likelihood of receiving a transplant. However, few studies have examined whether these same factors are associated with ESKD mortality. In this study, we examined county-level variation in ESKD mortality and identified county-level characteristics associated with this variation.

Methods

We identified 1,515,986 individuals (aged 18-84 years) initiating RRT (dialysis or transplant) between 2010 and 2018 using the United States Renal Data System. Among 2781 counties, we estimated county-level, all-cause, age-standardized mortality rates (ASMR) among patients with ESKD. We then identified county-level demographic (e.g., percent female), socioeconomic (e.g., percent unemployed), healthcare (e.g., percent without health insurance), and health behavior (e.g., percent current smokers) characteristics associated with ASMR using multivariable hierarchic linear mixed models and quantified the percentage of ASMR variation explained by county-level characteristics.

Results

County-level ESKD ASMR ranged from 45 to 1022 per 1000 person-years (PY) (mean, 119 per 1000 PY). ASMRs were highest in counties located in the Tennessee Valley and Appalachia regions, and lowest in counties located in New England, the Pacific Northwest, and Southern California. In fully adjusted models, county-level characteristics significantly associated with higher ESKD mortality included a lower percentage of Black residents (-4.94 per 1000 PY), lower transplant rate (-4.08 per 1000 PY), and higher healthcare expenditures (5.21 per 1000 PY). Overall, county-level characteristics explained 19% of variation in ESKD mortality.

Conclusions

Counties with high ESKD-related mortality may benefit from targeted and multilevel interventions that combine knowledge from a growing evidence base on the interplay between individual and community-level factors associated with ESKD mortality.

Bone Marrow Findings in Renal Patients: A Single Renal Specialist Center Experience

Objective

This study evaluated the importance of bone marrow aspiration and trephine biopsy (BM) for the diagnosis of underlying hematological abnormalities in renal patients.

Methods

This cross-sectional study on BM was carried out between August 2010 and April 2019, in our specialist renal center for various unexplained hematological abnormalities in patients with renal diseases [chronic kidney disease (CKD), end-stage renal disease (ESRD) requiring maintenance hemodialysis (MHD), patients with normal renal function but other nephrology and urology issues like stone disease and nephrotic syndrome].

Results

Out of 176 reported BM examinations, 48 (27.3%) were done on ESRD patients on MHD (CKD-D), and 69 (39.2%) on CKD patients not on MHD (CKD-nD). Fifty-nine (33.5%) BM were done on patients with normal renal function (n-CKD). The indication for BM was pancytopenia 50 (28.4%), unexplained anemia 39 (22.2%), and unexplained thrombocytopenia 43 (24.4%). In 91 (51.7%) patients BM was normal. In 30 (17%) patients multiple myeloma (MM) was diagnosed on BM, out of which 18 (26.1%), nine (18%), three (5.3%) were CKD-nD, CKD-D, and n-CKD patients, respectively. In 11 (6.3%) patients BM was suggestive of myelodysplasia (MD), out of these 11 patients, five (10%) were CKD-D patients.

Conclusion

BM is an underutilized method of diagnosis of hematological abnormalities in renal patients. Our study revealed the importance of BM examination, especially in patients with CKD.

Population-based Trends in Obesity and Kidney Transplantation Among Patients With End-stage Kidney Disease

Obesity is a barrier to transplant, reducing access and leading to worse outcomes versus nonobese adults. Most transplant centers in the United States maintain body mass index (BMI) cutoffs to listing for kidney transplantation of 35 to 40 kg/m². There is little contemporary data on the prevalence of obesity among patients with end-stage kidney disease (ESKD) despite its impact on clinical outcomes and healthcare expenditures.

Methods

We utilized data from the US Renal Data System from 2008 to 2016 to identify a prevalent cohort of 1 079 410 patients with ESKD. Linear regression determined trends in the proportion of patients within each category of BMI. We also evaluated geographic variation in rates of obesity and transplantation across the United States.

Results

Among the 1 079 410 ESKD patients, the largest cohort of patients were those with obesity (n = 423 270; 39.2%). There were 309 707 (28.7%) patients with an overweight BMI and 274 683 (25.4%) with a normal BMI. The proportion of patients with obesity increased significantly from 36.8% in 2008 to 40.2% in 2016 (trend 0.28; 95% confidence interval, 0.05-0.51). There was significant geographic variation by state with rates of obesity ranging from 32.3% to 45.4% and state transplant rates among those obese patients ranging from 22.5% to 46.8%. There is a weak correlation between states with increased rates of obese ESKD patients and states with an increased obesity transplant rate as indicated with r = 0.40 (P = 0.003).

Conclusions

Beneficiaries with obesity are now the largest and fastest growing demographic among patients with ESKD in the United States.

Emergency department use by patients with end-stage renal disease in the United States

Background

We sought to describe the national characteristics of ED visits by patients with end-stage renal disease (ESRD) in the United States in order to improve the emergency treatment and screening of ESRD patients.

Methods

We analyzed data from 2014 to 2016 ED visits provided by the National Hospital Ambulatory Medical Care Survey. We sampled adult (age ≥ 18 years) ED patients with ESRD. By proportion or means of weighted sample variables, we quantified annual ED visits by patients with ESRD. We investigated demographics, ED resource utilization, clinical characteristics, and disposition of patients with ESRD and compared these to those of patients without ESRD. Logistic regression models were used to estimate the association between these characteristics and ESRD ED visits.

Results

Approximately 722,692 (7.78%) out of 92,899,685 annual ED visits represented ESRD patients. Males were more likely to be ESRD patients than females (aOR: 1.34; 95% CI: 1.09–1.66). Compare to whites, non-Hispanic Blacks were 2.55 times more likely to have ESRD (aOR: 2.55; 95% CI: 1.97–3.30), and Hispanics were 2.68 times more likely to have ESRD (95% CI: 1.95–3.69). ED patients with ESRD were more likely to be admitted to the hospital (aOR: 2.70; 95% CI: 2.13–3.41) and intensive care unit (ICU) (aOR: 2.21; 95% CI: 1.45–3.38) than patients without ESRD. ED patients with ESRD were more likely to receive blood tests and get radiology tests.

Conclusion

We described the unique demographic, socioeconomic, and clinical characteristics of ED patients with ESRD, using the most comprehensive, nationally representative study to date. These patients’ higher hospital and ICU admission rates indicate that patients with ESRD require a higher level of emergency care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12873-021-00420-8.

Risk of herpes zoster among patients with predialysis chronic kidney disease in a cohort study in Taiwan

BACKGROUND/OBJECTIVE

Patients on chronic dialysis are at risk of developing herpes zoster, but little systematic research focuses on the association between predialysis chronic kidney disease and herpes zoster. The objective of the study was to explore the association between predialysis chronic kidney disease and herpes zoster in Taiwan.

METHODS

A nation-based retrospective cohort study was performed using the 2005-2012 database of the Taiwan National Health Insurance Program. There were 16 655 subjects aged 20-84 years with newly diagnosed predialysis chronic kidney disease as the study group and 33 310 randomly selected subjects without chronic kidney disease as the comparison group. Both groups were matched with sex, age, comorbidities and the year of the index date. The incidence rates of herpes zoster in both groups were calculated. The multivariable Cox proportional hazards regression model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for herpes zoster associated with predialysis chronic kidney disease.

RESULTS

The overall incidence rate of herpes zoster was 1.4-fold higher in the predialysis chronic kidney disease group than that in the non-chronic kidney disease group (8.76 vs 6.27 per 1000 person-years, 95% CI 1.27-1.54; P < .001). After controlling for co-variables, the adjusted HR of herpes zoster was 1.38 (95% CI 1.25-1.53; P < .001) for subjects with predialysis chronic kidney disease compared with non-chronic kidney disease subjects. The adjusted HR increased to 1.65 for subjects with predialysis chronic kidney disease and with any comorbidity (95% CI 1.42-1.92; P < .001).

CONCLUSIONS

Patients with predialysis chronic kidney disease correlate with approximately 1.4-fold increased hazard of developing herpes zoster.

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.

Intraregional differences in renal function in the Northern Netherlands: The Lifelines Cohort Study

Background

Although the interregional disparity in chronic kidney disease (CKD) prevalence has been reported globally, little is known about differences in CKD prevalence within a region. We aimed to study the intraregional distribution of renal function in the Northern Netherlands and identify determinants of geographical differences in renal function.

Methods

We included 143,735 participants from the Lifelines population-based cohort in the Northern Netherlands. Spatial analysis was performed to identify regional clusters of lower eGFR (cold spots) and higher eGFR (hot spots) at the postal code level, without and with adjustment for clinical risk factors. Multivariate logistic regression was used to identify the contribution of neighborhood-level health-related behaviors, socioeconomic status, and environmental factors (air pollution parameters, urbanity) to regional clustering of lower eGFR.

Results

Significant spatial clustering of renal function was found for eGFR as well as for early stage renal function impairment (eGFR<90 ml/min/1.73 m²), (p<0.001). Spatial clustering persisted after adjustment of eGFR for clinical risk factors. In adjusted cold spots, the aggregate eGFR was lower (mean ± SD: 96.5±4.8 vs. 98.5±4.0 ml/min/1.73 m², p = 0.001), and the prevalence of early stage renal function impairment (35.8±10.9 vs. 28.7±9.8%, p<0.001) and CKD stages 3–5 was higher (median (interquartile range): 1.2(0.1–2.4) vs 0(0–1.4)%, p<0.001) than in hot spots. In multivariable logistic regression, exposure to NO₂ (Odd ratio [OR], 1.45; 95% confidence interval [95% CI], 1.19 to 1.75, p<0.001) was associated with cold spots (lower renal function), whereas proportion of fat intake in the diet (OR, 0.68; 95%CI, 0.48–0.97, P = 0.031) and income (OR, 0.91; 95%CI, 0.86–0.96, p<0.001) for median level income) were inversely related.

Conclusions

Significant intraregional clustering of renal function, early renal function impairment and CKD were observed in the Northern Netherlands even after adjustment for renal function-related clinical risk factors. Environmental (air pollution), neighborhood-level socioeconomic factors and diet are determinants of intraregional renal function distribution. Spatial analysis might be a useful adjunct to guide public health strategies for the prevention of CKD.

Proteomic and metabolomic approaches in the search for biomarkers in chronic kidney disease

Chronic kidney disease (CKD) is an aging-related disorder that represents a major global public health burden. Current biochemical biomarkers, such as serum creatinine and urinary albumin, have important limitations when used to identify the earliest indication of CKD or in tracking the progression to more advanced CKD. These issues underline the importance of finding and testing new molecular biomarkers that are capable of successfully meeting this clinical need. The measurement of changes in nature and/or levels of proteins and metabolites in biological samples from patients provide insights into pathophysiological processes. Proteomic and metabolomic techniques provide opportunities to record dynamic chemical signatures in patients over time. This review article presents an overview of the recent developments in the fields of metabolomics and proteomics in relation to CKD. Among the many different proteomic biomarkers proposed, there is particular interest in the CKD273 classifier, a urinary proteome biomarker reported to predict CKD progression and with implementation potential. Other individual non-invasive peptidomic biomarkers that are potentially relevant for CKD detection include type 1 collagen, uromodulin and mucin-1. Despite the limited sample sizes and variability of the metabolomics studies, some metabolites such as trimethylamine N-oxide, kynurenine and citrulline stand out as potential biomarkers in CKD.

Distribution of nephrologists and regional variation in the clinical severity of IgA nephropathy at biopsy diagnosis in Japan: a cross-sectional study

OBJECTIVES

The clinical severity of IgA nephropathy (IgAN) at the time of biopsy diagnosis differs significantly among cases. One possible determinant of any such difference is the time taken for referral from the primary care physician to a nephrologist, but the definitive cause remains unclear. This study examined the contribution of the number of nephrologists per regional population as a potential social factor influencing the clinical severity at diagnosis among patients with IgAN in Japan, which has an ethnically homogeneous population.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

Patients were registered in the Japan Renal Biopsy Registry (J-RBR), a nationwide multicentre registry, and 6426 patients diagnosed with IgAN were analysed. The facilities registered to the J-RBR were divided into 10 regions and the clinical features of IgAN at biopsy diagnosis, including renal function and level of proteinuria, were examined.

MAIN OUTCOME MEASURES

Renal prognosis risk at the time of biopsy diagnosis defined by Kidney Disease Improving Global Outcomes guideline 2012.

RESULTS

Among the regions, there were significant differences in the estimated glomerular filtration rate (67.5-91.4 mL/min/1.73 m²), urinary protein excretion rate (0.93-1.93 g/day) and renal prognosis risk group distribution at diagnosis. The severity of all clinical parameters was inversely correlated with the number of nephrologists per regional population, which showed an up to 2.7-fold difference among regions. A generalised linear mixed model revealed that a low number of nephrologists per regional population were significantly associated with fulfilment of clinical criteria indicating a very-high-risk renal prognosis (β=-0.484, 95% CI -0.959 to -0.010).

CONCLUSIONS

Among Japanese patients with IgAN, significant regional differences were detected in clinical severity at the time of diagnosis. Social factors, such as an uneven distribution of nephrologists across regions, may influence the timing of biopsy and determine such differences.

Efficacy of Follow-up Care System of Living Kidney Donors in Monitoring of Residual Kidney Function

BACKGROUND

The possibility of an increased risk of end-stage renal disease is a major concern associated with living kidney donation. Therefore, monitoring of residual kidney function becomes most essential.

METHODS

A data analysis of 156 living kidney donors (LKDs) was conducted. The efficacy of the long-term care system with regard to monitoring residual kidney function was evaluated.

RESULTS

The analyzed group consisted of 102 (65.4%) women. The mean follow-up period was 5.44 years. The rise in value of mean serum creatinine concentration after donation was observed, but it was within the range of normal during the observation period. Despite its initial decline after nephrectomy, mean glomerular filtration rate (GFR) remained >60 mL/min/1.73 m². A MDRD (Modification of Diet in Renal Disease) GFR in the range of 45-60 mL/min/1.73 m² was observed in 53 donors (33.97%). It was found to be <45.0 mL/min/1.73 m² in 15 cases (9.6%). No patient developed end-stage renal disease. Only 25.0% of those analyzed had their CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) GFR estimated on 45-60 mL/min/1.73 m² and 4.49% were found to have levels of <45 mL/min/1.73 m² (down to 33.7 mL/min/1.73 m²). Mean postdonation CKD-EPI GFR was estimated at 69.99% of its predonation value.

CONCLUSION

A reliable qualification process could minimize the probability of kidney donation by someone with an increased risk of chronic kidney failure. The CKD-EPI formula seems to be more precise than the MDRD for estimatation of LKDs' GFR, as their loss of GFR is a result of nephrectomy and not kidney or systemic disease. Using the MDRD formula may lead to inappropriate diagnosis of CKD in some cases.

Evidence of chronic kidney disease in veterans with incident diabetes mellitus

While chronic kidney disease (CKD) is regularly evaluated among patients with diabetes, kidney function may be significantly impaired before diabetes is diagnosed. Moreover, disparities in the severity of CKD in such a population are likely. This study evaluated the extent of CKD in a national cohort of 36,764 US veterans first diagnosed with diabetes between 2003 and 2013 and prior to initiating oral antidiabetic therapy. Evidence of CKD (any stage) at the time of diabetes diagnosis was determined using eGFR and urine-albumin-creatinine ratios, the odds of which were assessed using logistic regression controlling for patient characteristics. CKD was evident in 31.6% of veterans prior to being diagnosed with diabetes (age and gender standardized rates: 241.8 per 1,000 adults [overall] and 247.7 per 1,000 adult males), over half of whom had at least moderate kidney disease (stage 3 or higher). The odds of CKD tended to increase with age (OR: 1.88; 95% CI: 1.82-1.93), hemoglobin A1C (OR: 1.05; 95% CI: 1.04-1.06), systolic blood pressure (OR: 1.04; 95% CI: 1.027-1.043), and BMI (OR: 1.016; 95% CI: 1.011-1.020). Both Asian Americans (OR: 1.53; 95% CI: 1.15-2.04) and African Americans (OR: 1.11; 95% CI: 1.03-1.20) had higher adjusted odds of CKD compared to whites, and prevalence was highest in the Upper Midwest and parts of the Mid-South. Results suggest that evidence of CKD is common among veterans before a diabetes diagnosis, and certain populations throughout the country, such as minorities, may be afflicted at higher rates.

Risk Factors for Prognosis in Patients With Severely Decreased GFR

Introduction

Patients with chronic kidney disease (CKD) and estimated glomerular filtration rate (eGFR) <30 ml/min per 1.73 m² (corresponding to CKD stage G4+) comprise a minority of the overall CKD population but have the highest risk for adverse outcomes. Many CKD G4+ patients are older with multiple comorbidities, which may distort associations between risk factors and clinical outcomes.

Methods

We undertook a meta-analysis of risk factors for kidney failure treated with kidney replacement therapy (KRT), cardiovascular disease (CVD) events, and death in participants with CKD G4+ from 28 cohorts (n = 185,024) across the world who were part of the CKD Prognosis Consortium.

Results

In the fully adjusted meta-analysis, risk factors associated with KRT were time-varying CVD, male sex, black race, diabetes, lower eGFR, and higher albuminuria and systolic blood pressure. Age was associated with a lower risk of KRT (adjusted hazard ratio: 0.74; 95% confidence interval: 0.69–0.80) overall, and also in the subgroup of individuals younger than 65 years. The risk factors for CVD events included male sex, history of CVD, diabetes, lower eGFR, higher albuminuria, and the onset of KRT. Systolic blood pressure showed a U-shaped association with CVD events. Risk factors for mortality were similar to those for CVD events but also included smoking. Most risk factors had qualitatively consistent associations across cohorts.

Conclusion

Traditional CVD risk factors are of prognostic value in individuals with an eGFR <30 ml/min per 1.73 m², although the risk estimates vary for kidney and CVD outcomes. These results should encourage interventional studies on correcting risk factors in this high-risk population.

A simple questionnaire to detect chronic kidney disease patients from Long An province screening data in Vietnam

BACKGROUND

The prevalence of chronic kidney disease (CKD) in rural Vietnam is unknown. We wished to determine the prevalence of CKD and determine whether a simple questionnaire was able to detect individuals at high risk of CKD before expensive confirmatory laboratory testing.

METHODS

A cross sectional study was performed. We recruited 2037 participants from 13 communes of Long An province, Vietnam, for CKD screening with urine albumin/creatinine ratio (ACR) measured by immunoturbidimetric method and serum creatinine to estimate glomerular filtration rate (eGFR). CKD was defined as either ACR ≥ 30 mg/g or eGFR MDRD < 60 ml/min/1.73 m2. A two page questionnaire with 23 variables was administered to each participant with queries postulated to be correlated with risk of CKD.

RESULTS

Of the 2037 participants, 260 (12.76%) were found to have CKD. Five questionnaire variables (age more than 50, measured hypertension, history of diabetes, history of hypertension, and history of a low salt diet) were correlated with CKD, and used to construct a risk score for CKD.

CONCLUSIONS

CKD is common in Vietnam. Our questionnaire and risk score tool can be used to detect individuals with a higher likelihood of CKD, and who can then be more economically screened with routine laboratory confirmatory tests.

Disparities in chronic medical conditions in the Mid-South

OBJECTIVE

This study examined differences in socio-demographic characteristics and health behaviors relevant to chronic medical conditions (CMCs) in the Mid-South region (Alabama, Mississippi, Louisiana, Kentucky, Tennessee, and Arkansas), and identified subpopulations with increased burden of chronic disease.

METHODS

Data were obtained from the 2013 Behavioral Risk Factor Surveillance System. The top five most prevalent CMCs in the Mid-South were analyzed: asthma, high blood pressure (HBP), obesity, arthritis, and depression. Adjusted odds ratios (AOR) and confidence intervals (CI) of race-gender combinations were estimated using logistic regression. Differences in associations between socio-demographic characteristics and CMCs according to income were also examined.

RESULTS

The weighted prevalence estimates of the top five CMCs ranged from 66% (asthma) to 20% (depression). Higher income and employment were associated with better outcomes in all five CMCs. Higher educational attainment and physical activity were associated with better HBP, obesity, and arthritis status. Black and white females had higher odds of asthma compared to white males (black AOR = 1.7, CI: 1.1-2.6, white AOR = 1.7, CI: 1.3-2.2). Black males had lower odds of arthritis (AOR = 0.8, CI: 0.6-0.9), while white females had higher odds (AOR = 1.3, CI: 1.2-1.4). Similarly, the odds of depression were lower among black males (AOR = 0.5, CI: 0.4-0.6) and higher among white females (AOR = 2.2, CI: 2.0-2.5). Income-related differences by race were observed for HBP and obesity.

CONCLUSION

Disparities in CMCs are associated with income and disproportionately affect the black population. In the Mid-South, race and gender disparities in the top five chronic conditions are more prominent among higher-income rather than lower-income individuals.

Sociodemographic Patterns of Chronic Disease: How the Mid-South Region Compares to the Rest of the Country

INTRODUCTION

States in the Mid-South region are among the least healthy in the nation. This descriptive study examines sociodemographic differences in the distribution of chronic diseases and health-related behaviors in the Mid-South versus the rest of the U.S., identifying subgroups at increased risk of chronic disease.

METHODS

Data were obtained from the 2013 Behavioral Risk Factor Surveillance System; analyses were completed in January 2016. Twelve chronic health conditions were assessed: obesity, diabetes, high blood pressure, coronary heart disease, myocardial infarction, stroke, chronic kidney disease, cancer, arthritis, asthma, chronic obstructive pulmonary disease, and depression. Evaluated health-related behaviors included smoking, physical activity, and fruit and vegetable consumption. Age-standardized percentages were reported using complex survey design parameters to enhance generalizability.

RESULTS

The Mid-South population had increased rates of chronic disease and worse health-related behaviors than the rest of the U.S.

POPULATION

Mid-South blacks had the highest percentages of obesity, diabetes, high blood pressure, and stroke of all subgroups, along with lower physical activity and fruit and vegetable consumption. In both races and regions, individuals with lower income and education had higher rates of chronic disease and unhealthy behaviors than those with higher income and education. However, black men in both regions had higher obesity and cancer rates in the higher education category. In general, education-level disparities were more pronounced in health-related behaviors, whereas income-level disparities were more pronounced in chronic health conditions.

CONCLUSIONS

Future studies should test tailored interventions to address the specific needs of population subgroups in order to improve their health.

Geographic Variation and US County Characteristics Associated With Rapid Kidney Function Decline

Introduction

Geographic variation in the prevalence of chronic kidney disease and incidence of end-stage renal disease has been previously reported. However, the geographic epidemiology of rapid estimated glomerular filtration rate (eGFR) decline has not been examined.

Methods

We built a longitudinal cohort of 2,107,570 US veterans to characterize the spatial epidemiology of and examine the associations between US county characteristics and rapid eGFR decline.

Results

There were 169,029 (8.02%) with rapid eGFR decline (defined as eGFR slope < –5 ml/min per 1.73 m²/year). The prevalence of rapid eGFR decline adjusted for age, race, gender, diabetes, and hypertension varied by county from 4.10%–6.72% in the lowest prevalence quintile to 8.41%–22.04% in the highest prevalence quintile (P for heterogeneity < 0.001). Examination of adjusted prevalence showed substantial geographic variation in those with and without diabetes and those with and without hypertension (P for heterogeneity < 0.001). Cohort participants had higher odds of rapid eGFR decline when living in counties with unfavorable characteristics in domains including health outcomes (odds ratio [OR] = 1.15; confidence interval [CI] = 1.09–1.22), health behaviors (OR = 1.08; CI = 1.03–1.13), clinical care (OR = 1.11; CI = 1.06–1.16), socioeconomic conditions (OR = 1.15; CI = 1.09–1.22), and physical environment (OR = 1.15; CI = 1.01–1.20); living in counties with high percentage of minorities and immigrants was associated with rapid eGFR decline (OR = 1.25; CI = 1.20–1.31). Spatial analyses suggest the presence of cluster of counties with high prevalence of rapid eGFR decline.

Discussion

Our findings show substantial geographic variation in rapid eGFR decline among US veterans; the variation persists in analyses stratified by diabetes and hypertension status; results show associations between US county characteristics in domains capturing health, socioeconomic, environmental, and diversity conditions, and rapid eGFR decline.

Renal Dysfunction in Post-Stroke Patients

BACKGROUND

The presence of chronic kidney disease (CKD) is an indicator of a worse long-term prognosis in patients with ischemic stroke (IS). Unfortunately, not much is known about renal function in the population of post-IS subjects. The aim of our study was to assess the prevalence of renal damage and impaired renal function (IRF) in the population of post-IS subjects.

METHODS

This prospective analysis concerned 352 consecutive post-IS survivors hospitalized in Pomeranian stroke centers (Poland) in 2009. In this group estimated glomerular filtration rate (eGFR) according to MDRD (modification of diet in renal diseases) and CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formulas and urine albumin/creatinine ratio (ACR) were determined.

RESULTS

Among survivors decreased eGFR (<60 mL/min./1.73m2 according to MDRD or CKD-EPI) or ACR≥30mg/g were detected in 40.38% (23.07% Men, 55.32% Women; P<0.01). The highest prevalence of IRF was noted in post-IS subjects with atheromatic and lacunar IS. In multivariate analysis the ACR≥30mg/g was predicted by older age, diabetes mellitus (DM) and physical disability (modified Rankin scale 3-5 pts.). The association with reduced eGFR was proved for sex (female), DM and physical disability.

CONCLUSIONS

CKD is a frequently occurring problem in the group of post-IS subjects, especially after lacunar and atheromatic IS. Post-IS patients, mainly the elderly women, with physical disability and diabetes mellitus, should be regularly screened for CKD. This could reduce the risk of further cardiovascular events and delay the progression of IRF.

Nephrotoxic Medication Exposure in U.S. Adults with Predialysis Chronic Kidney Disease: Health Services Utilization and Cost Outcomes

BACKGROUND

Nephrotoxic medication exposure increases risks for acute kidney injury, permanent renal function loss, and costly preventable adverse drug events. Exposure to medications associated with inducing acute tubular nephritis or tubular toxicity versus nonexposure among those with predialysis renal disease-a population vulnerable to increased risk of kidney injury-may affect health services utilization and cost outcomes. Few studies quantify nephrotoxic medication exposure in chronic kidney disease (CKD) and associated costs.

OBJECTIVE

To examine exposure to medications associated with inducing acute tubular nephritis or tubular toxicity versus nonexposure and the effect on health services utilization and cost outcomes in a nationally representative sample of adults with predialysis CKD.

METHODS

This retrospective study used Medical Expenditure Panel Survey (MEPS) household component longitudinal files (years 2006-2012; panels 11-16). Participants included 809 MEPS respondents aged > 18 years with predialysis CKD, after excluding those participants with cancer, kidney stone, renal dialysis, or transplant procedures (approximately 14.7 million U.S. noninstitutionalized individuals). Two groups were created to evaluate the main measures: (1) participants prescribed 1 or more medications associated with risk of acute tubular nephritis and/or tubular toxicity (termed "nephrotoxic exposure") and (2) participants with nonexposure. Medications cited in published literature as associated with tubular kidney damage were used. Multivariable regression models assessed the pattern of nephrotoxic medication exposure and its effect on health services utilization and expenses.

RESULTS

Nephrotoxic medication exposure occurred in 72% of adult MEPS respondents. Of those, 47.2% and 52.8% were prescribed 1 and at least 2 nephrotoxic medications, respectively. Coexistent chronic conditions included hypertension (72.3%), diabetes (49.5%), coronary heart disease (33%), arthritis (23.6%), and chronic obstructive pulmonary disease (17.6%). Eligible MEPS respondents aged ≥ 65 years, from the U.S. South region, and with Charlson Comorbidity Index (CCI) score > 0 were 75% (vs. aged 18-45 years), 83% (vs. Northeast), and 72%-96% (vs. CCI = 0) more likely to be exposed to nephrotoxic medications. Uninsured participants showed 55% less likelihood of nephrotoxic exposure, compared with privately insured participants. Higher utilization was shown in the nephrotoxic medication exposure group (vs. nonexposure): prescription fills (52.8 vs. 26.8, P < 0.001), emergency department visits (56.2 vs. 29.3 per 1,000 patient months, P < 0.001), and hospitalization (51.8 vs. 23.4 per 1,000 patient months, P < 0.001). Unadjusted all-cause expenses were greater for the following categories: medical ($119,935 vs. $11,462, P < 0.001), prescription drug ($4,828 vs. $2,816, P < 0.001), and total health expenses ($24,663 vs. $14,277, P < 0.001). Adjusted all-cause expenses were greater for total (29.7% greater, P = 0.003), prescription medications (56.6% greater, P < 0.001), and medical (23.4% greater, P = 0.036), but there were no differences in predialysis CKD-related utilization and expenses.

CONCLUSIONS

Increased vigilance is needed when prescribing nephrotoxic medications in predialysis CKD, particularly in patients with comorbid conditions and the elderly. Nephrotoxic medication exposure in predialysis CKD has the potential for increased health services utilization and cost outcomes.

DISCLOSURES

There was no grant or intramural funding for this research. The authors have no conflicts of interest, financial or otherwise, to disclose. Study concept and design were primarily contributed by Davis-Ajami, along with Fink and Wu. Davis-Ajami took the lead in data collection, along with Wu, and data interpretation was performed by David-Ajami, Wu, and Fink. All authors participated in manuscript preparation and revision.

Global Prevalence of Chronic Kidney Disease - A Systematic Review and Meta-Analysis

Chronic kidney disease (CKD) is a global health burden with a high economic cost to health systems and is an independent risk factor for cardiovascular disease (CVD). All stages of CKD are associated with increased risks of cardiovascular morbidity, premature mortality, and/or decreased quality of life. CKD is usually asymptomatic until later stages and accurate prevalence data are lacking. Thus we sought to determine the prevalence of CKD globally, by stage, geographical location, gender and age. A systematic review and meta-analysis of observational studies estimating CKD prevalence in general populations was conducted through literature searches in 8 databases. We assessed pooled data using a random effects model. Of 5,842 potential articles, 100 studies of diverse quality were included, comprising 6,908,440 patients. Global mean(95%CI) CKD prevalence of 5 stages 13·4%(11·7-15·1%), and stages 3-5 was 10·6%(9·2-12·2%). Weighting by study quality did not affect prevalence estimates. CKD prevalence by stage was Stage-1 (eGFR>90+ACR>30): 3·5% (2·8-4·2%); Stage-2 (eGFR 60-89+ACR>30): 3·9% (2·7-5·3%); Stage-3 (eGFR 30-59): 7·6% (6·4-8·9%); Stage-4 = (eGFR 29-15): 0·4% (0·3-0·5%); and Stage-5 (eGFR<15): 0·1% (0·1-0·1%). CKD has a high global prevalence with a consistent estimated global CKD prevalence of between 11 to 13% with the majority stage 3. Future research should evaluate intervention strategies deliverable at scale to delay the progression of CKD and improve CVD outcomes.

CKD Prevalence Varies across the European General Population

CKD prevalence estimation is central to CKD management and prevention planning at the population level. This study estimated CKD prevalence in the European adult general population and investigated international variation in CKD prevalence by age, sex, and presence of diabetes, hypertension, and obesity. We collected data from 19 general-population studies from 13 European countries. CKD stages 1-5 was defined as eGFR<60 ml/min per 1.73 m(2), as calculated by the CKD-Epidemiology Collaboration equation, or albuminuria >30 mg/g, and CKD stages 3-5 was defined as eGFR<60 ml/min per 1.73 m(2) CKD prevalence was age- and sex-standardized to the population of the 27 Member States of the European Union (EU27). We found considerable differences in both CKD stages 1-5 and CKD stages 3-5 prevalence across European study populations. The adjusted CKD stages 1-5 prevalence varied between 3.31% (95% confidence interval [95% CI], 3.30% to 3.33%) in Norway and 17.3% (95% CI, 16.5% to 18.1%) in northeast Germany. The adjusted CKD stages 3-5 prevalence varied between 1.0% (95% CI, 0.7% to 1.3%) in central Italy and 5.9% (95% CI, 5.2% to 6.6%) in northeast Germany. The variation in CKD prevalence stratified by diabetes, hypertension, and obesity status followed the same pattern as the overall prevalence. In conclusion, this large-scale attempt to carefully characterize CKD prevalence in Europe identified substantial variation in CKD prevalence that appears to be due to factors other than the prevalence of diabetes, hypertension, and obesity.

Food Access, Chronic Kidney Disease, and Hypertension in the U.S

INTRODUCTION

Greater distance to full-service supermarkets and low income may impair access to healthy diets and contribute to chronic kidney disease (CKD) and hypertension. The study aim was to determine relationships among residence in a "food desert," low income, CKD, and blood pressure.

METHODS

Adults in the 2003-2010 National Health and Nutrition Examination Survey (N=22,173) were linked to food desert data (www.ers.usda.gov) by Census Tracts. Food deserts have low median income and are further from a supermarket or large grocery store (>1 mile in urban areas, >10 miles in rural areas). Weighted regression was used to determine the association of residence in a food desert and family income with dietary intake; systolic blood pressure (SBP); and odds of CKD. Data analysis was performed in 2014-2015.

RESULTS

Compared with those not in food deserts, participants residing in food deserts had lower levels of serum carotenoids (p<0.01), a biomarker of fruit and vegetable intake, and higher SBP (1.53 mmHg higher, 95% CI=0.41, 2.66) after adjustment for demographics and income. Residence in a food desert was not associated with odds of CKD (OR=1.20, 95% CI=0.96, 1.49). Lower, versus higher, income was associated with lower serum carotenoids (p<0.01) and higher SBP (2.00 mmHg higher for income-poverty ratio ≤1 vs >3, 95% CI=1.12, 2.89), but also greater odds of CKD (OR=1.76 for income-poverty ratio ≤1 vs >3, 95% CI=1.48, 2.10).

CONCLUSIONS

Limited access to healthy food due to geographic or financial barriers could be targeted for prevention of CKD and hypertension.

Kidney Failure and ESRD in the Atherosclerosis Risk in Communities (ARIC) Study: Comparing Ascertainment of Treated and Untreated Kidney Failure in a Cohort Study

BACKGROUND

Linkage to the US Renal Data System (USRDS) registry commonly is used to identify end-stage renal disease (ESRD) cases, or kidney failure treated with dialysis or transplantation, but it underestimates the total burden of kidney failure. This study validates a kidney failure definition that includes both kidney failure treated and not treated by dialysis or transplantation. It compares kidney failure risk factors and outcomes using this broader definition with USRDS-identified ESRD risk factors and outcomes.

STUDY DESIGN

Diagnostic test study with stratified random sampling of hospitalizations for chart review.

SETTING & PARTICIPANTS

Atherosclerosis Risk in Communities Study (n=11,530; chart review, n=546).

INDEX TEST

USRDS-identified ESRD; treated or untreated kidney failure defined by USRDS-identified ESRD or International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification (ICD-9-CM/ICD-10-CM) code for hospitalization or death.

REFERENCE TEST

For ESRD, determination of permanent dialysis therapy or transplantation; for kidney failure, determination of permanent dialysis therapy, transplantation, or estimated glomerular filtration rate < 15 mL/min/1.73 m(2).

RESULTS

During 13 years' median follow-up, 508 kidney failure cases were identified, including 173 (34.1%) from the USRDS registry. ESRD and kidney failure incidence were 1.23 and 3.66 cases per 1,000 person-years in the overall population and 1.35 and 6.59 cases per 1,000 person-years among participants older than 70 years, respectively. Other risk-factor associations were similar between ESRD and kidney failure, except diabetes and albuminuria, which were stronger for ESRD. Survivals at 1 and 5 years were 74.0% and 24.0% for ESRD and 59.8% and 31.6% for kidney failure, respectively. Sensitivity and specificity were 88.0% and 97.3% comparing the kidney failure ICD-9-CM/ICD-10-CM code algorithm to chart review; for USRDS-identified ESRD, sensitivity and specificity were 94.9% and 100.0%.

LIMITATIONS

Some medical charts were incomplete.

CONCLUSIONS

A kidney failure definition including treated and untreated disease identifies more cases than linkage to the USRDS registry alone, particularly among older adults. Future studies might consider reporting both USRDS-identified ESRD and a more inclusive kidney failure definition.

Disparities in the burden, outcomes, and care of chronic kidney disease

PURPOSE OF REVIEW

Racial, ethnic and socioeconomic disparities in chronic kidney disease (CKD) have been documented for decades, yet little progress has been made in mitigating them. Several recent studies offer new insights into the root causes of these disparities, point to areas in which future research is warranted, and identify opportunities for changes in policy and clinical practice.

RECENT FINDINGS

Recently published evidence suggests that geographic disparities in CKD prevalence exist and vary by race. CKD progression is more rapid for racial and ethnic minority groups compared with whites and may be largely, but not completely, explained by genetic factors. Stark socioeconomic disparities in outcomes for dialysis patients exist and vary by race, place of residence, and treatment facility. Disparities in access to living kidney donation may be driven primarily by the socioeconomic status of the donor as opposed to recipient factors.

SUMMARY

Recent studies highlight opportunities to eliminate disparities in CKD, including efforts to direct resources to areas and populations where disparities are most prevalent, efforts to understand how to best use emerging information on the contribution of genetic factors to disparities, and continued work to identify modifiable environmental, social, and behavioral factors for targeted interventions among high-risk populations.

Mapping end-stage renal disease (ESRD): spatial variations on small area level in northern France, and association with deprivation

BACKGROUND

Strong geographic variations in the incidence of end-stage renal disease (ESRD) are observed in developed countries. The reasons for these variations are unknown. They may reflect regional inequalities in the population's sociodemographic characteristics, related diseases, or medical practice patterns. In France, at the district level, the highest incidence rates have been found in the Nord-Pas-de-Calais region. This area, with a high population density and homogeneous healthcare provision, represents a geographic situation which is quite suitable for the study, over small areas, of spatial disparities in the incidence of ESRD, together with their correlation with a deprivation index and other risk factors.

METHODS

The Renal Epidemiology and Information Network is a national registry, which lists all ESRD patients in France. All cases included in the Nord-Pas-de-Calais registry between 2005 and 2011 were extracted. Adjusted and smoothed standardized incidence ratio (SIR) was calculated for each of the 170 cantons, thanks to a hierarchical Bayesian model. The correlation between ESRD incidence and deprivation was assessed using the quintiles of Townsend index. Relative risk (RR) and credible intervals (CI) were estimated for each quintile.

RESULTS

Significant spatial disparities in ESRD incidence were found within the Nord-Pas-de-Calais region. The sex- and age-adjusted, smoothed SIRs varied from 0.66 to 1.64. Although no correlation is found with diabetic or vascular nephropathy, the smoothed SIRs are correlated with the Townsend index (RR: 1.18, 95% CI [1.00-1.34] for Q2; 1.28, 95% CI [1.11-1.47] for Q3; 1.30, 95% CI [1.14-1.51] for Q4; 1.44, 95% CI [1.32-1.74] for Q5).

CONCLUSION

For the first time at this aggregation level in France, this study reveals significant geographic differences in ESRD incidence. Unlike the time of renal replacement care, deprivation is certainly a determinant in this phenomenon. This association is probably independent of the patients' financial ability to gain access to healthcare.

Methods and feasibility of collecting occupational data for a large population-based cohort study in the United States: the reasons for geographic and racial differences in stroke study

BACKGROUND

Coronary heart disease and stroke are major contributors to preventable mortality. Evidence links work conditions to these diseases; however, occupational data are perceived to be difficult to collect for large population-based cohorts. We report methodological details and the feasibility of conducting an occupational ancillary study for a large U.S. prospective cohort being followed longitudinally for cardiovascular disease and stroke.

METHODS

Current and historical occupational information were collected from active participants of the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study. A survey was designed to gather quality occupational data among this national cohort of black and white men and women aged 45 years and older (enrolled 2003-2007). Trained staff conducted Computer-Assisted Telephone Interviews (CATI). After a brief pilot period, interviewers received additional training in the collection of narrative industry and occupation data before administering the survey to remaining cohort members. Trained coders used a computer-assisted coding system to assign U.S. Census codes for industry and occupation. All data were double coded; discrepant codes were independently resolved.

RESULTS

Over a 2-year period, 17,648 participants provided consent and completed the occupational survey (87% response rate). A total of 20,427 jobs were assigned Census codes. Inter-rater reliability was 80% for industry and 74% for occupation. Less than 0.5% of the industry and occupation data were uncodable, compared with 12% during the pilot period. Concordance between the current and longest-held jobs was moderately high. The median time to collect employment status plus narrative and descriptive job information by CATI was 1.6 to 2.3 minutes per job. Median time to assign Census codes was 1.3 minutes per rater.

CONCLUSIONS

The feasibility of conducting high-quality occupational data collection and coding for a large heterogeneous population-based sample was demonstrated. We found that training for interview staff was important in ensuring that narrative responses for industry and occupation were adequately specified for coding. Estimates of survey administration time and coding from digital records provide an objective basis for planning future studies. The social and environmental conditions of work are important understudied risk factors that can be feasibly integrated into large population-based health studies.