Longitudinal study of racial and ethnic differences in developing end-stage renal disease among aged medicare beneficiaries

Role of Age and Competing Risk of Death in the Racial Disparity of Kidney Failure Incidence after Onset of CKD

SIGNIFICANCE STATEMENT

Black adults in the United States have 2-4 times higher incidence of kidney failure than White adults. Yet, the reasons underlying this disparity remain poorly understood. Among 547,188 US veterans with new-onset CKD, according to a new race-free GFR equation, Black veterans had a 2.5-fold higher cumulative incidence of kidney failure, compared with White veterans, in any follow-up period from CKD onset. This disparity resulted from a combination of higher hazards of progression to kidney failure and lower hazards of competing-risk death in Black veterans. Both, in turn, were largely explained by the younger age at CKD onset in Black veterans, underscoring an urgent need to prevent early onset and slow progression of CKD in younger Black adults.

BACKGROUND

The Black adult population is well known to have higher incidence of kidney failure than their White counterpart in the United States, but the reasons underlying this disparity are unclear. We assessed the racial differences in kidney failure and death from onset of CKD on the basis of the race-free 2021 CKD Epidemiology Collaboration equation and examined the extent to which these differences could be explained by factors at the time of CKD onset.

METHODS

We analyzed a national cohort consisting of 547,188 US veterans (103,821 non-Hispanic Black and 443,367 non-Hispanic White), aged 18-85 years, with new-onset CKD between 2005 and 2016 who were followed through 10 years or May 2018 for incident kidney failure with replacement therapy (KFRT) and pre-KFRT death.

RESULTS

At CKD onset, Black veterans were, on average, 7.8 years younger than White veterans. In any time period from CKD onset, the cumulative incidence of KFRT was 2.5-fold higher for Black versus White veterans. Meanwhile, Black veterans had persistently >2-fold higher hazards of KFRT throughout follow-up (overall hazard ratio [95% confidence interval], 2.38 [2.31 to 2.45]) and conversely had 17%-48% decreased hazards of pre-KFRT death. These differences were reduced after accounting for the racial difference in age at CKD onset.

CONCLUSIONS

The 2.5-fold higher cumulative incidence of kidney failure in Black adults resulted from a combination of higher hazards of progression to kidney failure and lower hazards of the competing risk of death, both of which can be largely explained by the younger age at CKD onset in Black compared with White adults.

Genome-wide study investigating effector genes and polygenic prediction for kidney function in persons with ancestry from Africa and the Americas

Chronic kidney disease is a leading cause of death and disability globally and impacts individuals of African ancestry (AFR) or with ancestry in the Americas (AMS) who are under-represented in genome-wide association studies (GWASs) of kidney function. To address this bias, we conducted a large meta-analysis of GWASs of estimated glomerular filtration rate (eGFR) in 145,732 AFR and AMS individuals. We identified 41 loci at genome-wide significance (p < 5 × 10-8), of which two have not been previously reported in any ancestry group. We integrated fine-mapped loci with epigenomic and transcriptomic resources to highlight potential effector genes relevant to kidney physiology and disease, and reveal key regulatory elements and pathways involved in renal function and development. We demonstrate the varying but increased predictive power offered by a multi-ancestry polygenic score for eGFR and highlight the importance of population diversity in GWASs and multi-omics resources to enhance opportunities for clinical translation for all.

Racial Disparities in Health Beliefs and Advance Care Planning Among Patients Receiving Maintenance Dialysis

CONTEXT

Among people receiving maintenance dialysis, little is known about racial disparities in the occurrence of prognostic discussions, beliefs about future health, and completion of advance care planning (ACP) documents.

OBJECTIVES

We examined whether Black patients receiving maintenance dialysis differ from White patients in prognostic discussions, beliefs about future health, and completion of ACP-related documents.

METHODS

We surveyed adult patients receiving maintenance dialysis from seven dialysis units in Cleveland, Ohio, and hospitalized patients at a tertiary care hospital in Cleveland. Of the 450 patients who were asked to participate in the study, 423 (94%) agreed. We restricted the current secondary analyses to include only Black (n=285) and White (n=114) patients. The survey assessed patients' knowledge of their kidney disease, attitudes toward chronic kidney disease (CKD) treatment, preferences for end-of-life (EoL) care, the patient-reported occurrence of prognostic discussions, experiences with kidney therapy decision making, sentiments of dialysis regret, beliefs about health over the next 12 months, and advance care planning. We used stepwise logistic regression to determine if race was associated with the occurrence of prognostic discussions, beliefs about future health, and completion of an ACP-related document, while controlling for potential confounders.

RESULTS

We found no significant difference in the frequency of prognostic discussions between Black (11.9%) versus White patients (7%) (P=0.15). However, Black patients (19%) had lower odds of believing that their health would worsen over the next 12 months (OR 0.22, CI 0.12, 0.44) and reporting completion of any ACP-related document (OR 0.5, CI 0.32, 0.81) compared to White patients CONCLUSION: Racial differences exist in beliefs about future health and completion of ACP-related documents. Systemic efforts to investigate differences in health beliefs and address racial disparities in the completion of ACP-related documents are needed.

Changes in racial and ethnic disparities in glucose-lowering drug utilization and glycated haemoglobin A1c in US adults with diabetes: 2005-2018

AIM

To examine changes in racial and ethnic disparities in glucose-lowering drugs (GLD) use and glycated haemoglobin A1c in US adults with diabetes from 2005 to 2018.

METHODS

We conducted pooled cross-sectional analysis using data from the 2005-2018 Medical Expenditure Panel Surveys, and the 2005-2018 National Health and Nutrition Examination Survey. Individuals ≥18 years with diabetes were included. Racial and ethnic disparities were measured in (a) newer non-insulin GLD use; (b) insulin analogue use; (c) non-insulin GLDs adherence; (d) insulin adherence; and (e) glucose management, along with (f) the proportion of the disparities explained by potential contributing factors.

RESULTS

From 2005 to 2018, racial and ethnic disparities persisted in newer GLD use, non-insulin GLDs adherence, insulin analogue use and glucose management. In 2018, compared with non-Hispanic white adults, non-Hispanic black, Hispanic and other race/ethnicity groups had lower rates of using newer GLDs (adjusted risk ratio: 0.44, 0.52, 0.64, respectively; p < .05 for all) and insulin analogues (adjusted risk ratio: 0.93, 0.89, 0.95, respectively; p < .05 for all except other groups), lower non-insulin GLD adherence (proportion of days covered: -4.5%, -5.6%, -4.3%, respectively; p < .05 for all), higher glycated haemoglobin A1c (0.29%, 0.32%, 0.02%, respectively; p < .05 for all except other group), and similar insulin adherences. Socioeconomic and health status were the main contributors to these disparities.

CONCLUSIONS

Our findings provide evidence of racial and ethnic disparities in newer GLD use and quality of care in glucose management. Our study results can inform decision-makers of the status of racial and ethnic disparities and identify ways to reduce these disparities.

Health Behavior Theory and Hypertension Management: Comparisons Among Black, White, and American Indian and Alaska Native Patients

In the United States, hypertension is more common among individuals from racial and ethnic minority groups. Hypertension control rates are also lower for minority group members compared with White Americans. However, little research has employed well-established theoretical perspectives on health behavior, such as the Theory of Planned Behavior (TPB) and the Model of Goal-Directed Behavior (MGB), to better understand racial differences in rates of hypertension control. The present study examines the psychological processes involved in efforts to control blood pressure, through the lens of the TPB augmented by the MGB, in hypertensive patients of three racial groups: American Indian/Alaska Native, Black/African American, and White. Participants completed measures of past efforts to control blood pressure, attitudes, norms, perceived behavioral control, intentions, and anticipated emotions. Analyses employed confirmatory factor analysis and cross-groups path analysis. Measurement of the theoretical constructs and core putative mediators of blood pressure control intentions were largely similar across racial groups. With regard to the patterns of relationships among the constructs, differences among the groups were most apparent in pathways from past efforts to both cognitive and affective theoretical antecedents of intentions. These findings contribute to the sparse literature on factors involved in racial differences in hypertension control rates and may inform future interventions aimed at increasing hypertension control behaviors. Trial Registration ClinicalTrials.gov, NCT03028597, registered 23 January 2017, https://clinicaltrials.gov/ct2/show/NCT03028597; ClinicalTrials.gov, NCT04414982, registered 4 June 2020 (retrospectively registered), https://www.clinicaltrials.gov/ct2/show/NCT04414982.

Sex Differences in the Recognition, Monitoring, and Management of CKD in Health Care: An Observational Cohort Study

INTRODUCTION

Reported sex differences in the etiology, population prevalence, progression rates, and health outcomes of people with CKD may be explained by differences in health care.

METHODS

We evaluated sex as the variable of interest in a health care-based study of adults (n=227,847) with at least one outpatient eGFR<60 ml/min per 1.73 m2 measurement denoting probable CKD in Stockholm from 2009 to 2017. We calculated the odds ratios for diagnosis of CKD and provision of RASi and statins at inclusion, and hazard ratios for CKD diagnosis, visiting a nephrologist, or monitoring creatinine and albuminuria during follow-up.

RESULTS

We identified 227,847 subjects, of whom 126,289 were women (55%). At inclusion, women had lower odds of having received a diagnostic code for CKD and were less likely to have received RASi and statins, despite having guideline-recommended indications. In time-to-event analyses, women were less likely to have received a CKD diagnosis (HR, 0.43; 95% CI, 0.42 to 0.45) and visited a nephrologist (HR, 0.46; 95% CI, 0.43 to 0.48) regardless of disease severity, presence of albuminuria, or criteria for referral. Women were also less likely to undergo monitoring of creatinine or albuminuria, including those with diabetes or hypertension. These differences remained after adjustment for comorbidities, albuminuria, and highest educational achievement, and among subjects with confirmed CKD at retesting. Although in absolute terms all nephrology-care indicators gradually improved over time, the observed sex gap persisted.

CONCLUSIONS

There were profound sex differences in the detection, recognition, monitoring, referrals, and management of CKD. The disparity was also observed in people at high risk and among those who had guideline-recommended indications.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/JASN/2022_10_11_JASN2022030373.mp3.

CKD Care Programs and Incident Kidney Failure: A Study of a National Disease Management Program in Taiwan

Rationale & Objective

Taiwan implemented national pay-for-performance programs for chronic kidney disease (CKD) care in 2006 and 2011; however, it is unknown whether this affected trends in maintenance dialysis. This study assessed the temporal trends in the incidence, prevalence, and mortality of individuals treated with maintenance dialysis from 2002-2016 in Taiwan.

Study Design

Follow-up study using Taiwan Renal Disease System Databases.

Setting & Participants

Participants who received dialysis for ≥90 days.

Predictors

Age, sex, and calendar year.

Outcomes

Incidence, prevalence of maintenance dialysis, or death, ascertained using the National Death Registry database.

Analytical Approach

The estimated annual percentage change was assessed by a generalized linear model, and the association of the programs with changes in the incidence of maintenance dialysis was evaluated using an age-period-cohort model.

Results

A total of 144,258 incident cases with a follow-up of 346 million person-years were analyzed during the observed periods. The estimated annual percentage change of the expected crude incidence rate was slightly reduced by 0.41% (95% CI, −1.06 to 0.24) and was more obvious in women and patients aged greater than 70 years; whereas, it was significantly increased in those aged greater than 75 years. After disentangling age and cohort effects, the implementation of the care programs was associated with an overall net drift of −1.09% (95% CI, −1.65 to −0.52) per year and a significant linear reduction in the period rate ratio from 1.06 (95% CI, 1.02-1.09) in the years 2002-2006 to 0.95 (95% CI, 0.92-0.98) in 2012-2016, using years 2007-2011 as reference.

Limitations

The findings of the study may have limited inferences to other countries with different health care systems.

Conclusions

The implementation of universal CKD care programs in Taiwan has significantly reduced the long-term trends in the incidence of maintenance dialysis; hence, devoting governmental resources to CKD care and prevention is advocated.

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.

Predictive Risk Models to Identify Patients at High-Risk for Severe Clinical Outcomes With Chronic Kidney Disease and Type 2 Diabetes

Introduction/Objective:

Predictive risk models identifying patients at high risk for specific outcomes may provide valuable insights to providers and payers regarding points of intervention and modifiable factors. The goal of our study was to build predictive risk models to identify patients with chronic kidney disease (CKD) and type 2 diabetes (T2D) at high risk for progression to end stage kidney disease (ESKD), mortality, and hospitalization for cardiovascular disease (CVD), cerebrovascular disease (CeVD), and heart failure (HF).

Methods:

This was a retrospective observational cohort study utilizing administrative claims data in patients with CKD (stage 3-4) and T2D aged 65 to 89 years enrolled in a Medicare Advantage Drug Prescription plan offered by Humana Inc. between 1/1/2012 and 12/31/2017. Patients were enrolled ≥1 year pre-index and followed for outcomes, including hospitalization for CVD, CeVD and HF, ESKD, and mortality, 2 years post-index. Pre-index characteristics comprising demographic, comorbidities, laboratory values, and treatment (T2D and cardiovascular) were evaluated and included in the models. LASSO technique was used to identify predictors to be retained in the final models followed by logistic regression to generate parameter estimates and model performance statistics. Inverse probability censoring weighting was used to account for varying follow-up time.

Results:

We identified 169 876 patients for inclusion. Declining estimated glomerular filtration rate (eGFR) increased the risk of hospitalization for CVD (38.6%-61.8%) and HF (2-3 times) for patients with eGFR 15 to 29 mL/min/1.73 m² compared to patients with eGFR 50 to 59 mL/min/1.73 m². Patients with urine albumin-to-creatinine ratio (UACR) ≥300 mg/g had greater chance for hospitalization for CVD (2.0 times) and HF (4.9 times), progression to ESKD (2.9 times) and all-cause mortality (2.4 times) than patients with UACR <30 mg/g. Elevated hemoglobin A1c (≥8%) increased the chances for hospitalization for CVD (21.3%), CeVD (45.4%), and death (20.6%). Among comorbidities, history of HF increased the risk for ESKD, mortality, and hospitalization for CVD, CeVD, and HF.

Conclusions:

The predictive models developed in this study could potentially be used as decision support tools for physicians and payers, and the risk scores from these models can be applied to future outcomes studies focused on patients with T2D and CKD.

Gender Differences in Diabetic Kidney Disease: Focus on Hormonal, Genetic and Clinical Factors

Diabetic kidney disease (DKD) is one of the most serious complications of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM). Current guidelines recommend a personalized approach in order to reduce the burden of DM and its complications. Recognizing sex and gender- differences in medicine is considered one of the first steps toward personalized medicine, but the gender issue in DM has been scarcely explored so far. Gender differences have been reported in the incidence and the prevalence of DKD, in its phenotypes and clinical manifestations, as well as in several risk factors, with a different impact in the two genders. Hormonal factors, especially estrogen loss, play a significant role in explaining these differences. Additionally, the impact of sex chromosomes as well as the influence of gene-sex interactions with several susceptibility genes for DKD have been investigated. In spite of the increasing evidence that sex and gender should be included in the evaluation of DKD, several open issues remain uncovered, including the potentially different effects of newly recommended drugs, such as SGLT2i and GLP1Ras. This narrative review explored current evidence on sex/gender differences in DKD, taking into account hormonal, genetic and clinical factors.

Sex disparities and adverse cardiovascular and kidney outcomes in patients with chronic kidney disease: results from the KNOW-CKD

AIMS

Longitudinal studies of the association between sex and adverse clinical outcomes in patients with chronic kidney disease (CKD) are scarce. We assessed whether major outcomes may differ by sex among CKD patients.

METHODS

We analyzed a total of 1780 participants with non-dialysis CKD G1-5 from the KoreaN cohort study for Outcome in patients with Chronic Kidney Disease (KNOW-CKD). The primary outcome was a composite of non-fatal cardiovascular events or all-cause mortality. Secondary outcomes included fatal and non-fatal cardiovascular events, all-cause mortality, and a composite kidney outcome of ≥ 50% decline in estimated glomerular filtration rate from baseline or the onset of end-stage kidney disease.

RESULTS

There were 1088 (61%) men and 692 (39%) women in the study cohort. The proportion of smokers was significantly higher in men (24% vs. 3%). During 8430 person-years of follow-up, 201 primary outcome events occurred: 144 (13%) in men and 57 (8%) in women, with corresponding incidence rates of 2.9 and 1.7 per 100 person-years, respectively. In multivariable Cox models, men were associated with a 1.58-fold (95% CI 1.06-2.35) higher risk of composite outcome. Propensity score matching analysis revealed similar findings (HR 1.81; 95% CI 1.14-2.91). Risk of all-cause mortality was significantly higher in men of the matched cohort. However, there was no difference in the risk of CKD progression. In the subgroup with coronary artery calcium (CAC) measurements, men had a higher likelihood of CAC progression.

CONCLUSIONS

In Korean CKD patients, men were more likely to experience adverse cardiovascular events and death than women.

Epigenome-wide association study of kidney function identifies trans-ethnic and ethnic-specific loci

BACKGROUND

DNA methylation (DNAm) is associated with gene regulation and estimated glomerular filtration rate (eGFR), a measure of kidney function. Decreased eGFR is more common among US Hispanics and African Americans. The causes for this are poorly understood. We aimed to identify trans-ethnic and ethnic-specific differentially methylated positions (DMPs) associated with eGFR using an agnostic, genome-wide approach.

METHODS

The study included up to 5428 participants from multi-ethnic studies for discovery and 8109 participants for replication. We tested the associations between whole blood DNAm and eGFR using beta values from Illumina 450K or EPIC arrays. Ethnicity-stratified analyses were performed using linear mixed models adjusting for age, sex, smoking, and study-specific and technical variables. Summary results were meta-analyzed within and across ethnicities. Findings were assessed using integrative epigenomics methods and pathway analyses.

RESULTS

We identified 93 DMPs associated with eGFR at an FDR of 0.05 and replicated 13 and 1 DMPs across independent samples in trans-ethnic and African American meta-analyses, respectively. The study also validated 6 previously published DMPs. Identified DMPs showed significant overlap enrichment with DNase I hypersensitive sites in kidney tissue, sites associated with the expression of proximal genes, and transcription factor motifs and pathways associated with kidney tissue and kidney development.

CONCLUSIONS

We uncovered trans-ethnic and ethnic-specific DMPs associated with eGFR, including DMPs enriched in regulatory elements in kidney tissue and pathways related to kidney development. These findings shed light on epigenetic mechanisms associated with kidney function, bridging the gap between population-specific eGFR-associated DNAm and tissue-specific regulatory context.

Association of Race/Ethnicity, Gender, and Socioeconomic Status With Sodium-Glucose Cotransporter 2 Inhibitor Use Among Patients With Diabetes in the US

IMPORTANCE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors significantly reduce deaths from cardiovascular conditions, hospitalizations for heart failure, and progression of kidney disease among patients with type 2 diabetes. Black individuals have a disproportionate burden of cardiovascular and chronic kidney disease (CKD). Adoption of novel therapeutics has been slower among Black and female patients and among patients with low socioeconomic status than among White or male patients or patients with higher socioeconomic status.

OBJECTIVE

To assess whether inequities based on race/ethnicity, gender, and socioeconomic status exist in SGLT2 inhibitor use among patients with type 2 diabetes in the US.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study of commercially insured patients in the US was performed from October 1, 2015, to June 30, 2019, using the Optum Clinformatics Data Mart. Adult patients with a diagnosis of type 2 diabetes, including those with heart failure with reduced ejection fraction (HFrEF), atherosclerotic cardiovascular disease (ASCVD), or CKD, were evaluated in the analysis.

MAIN OUTCOMES AND MEASURES

Prescription of an SGLT2 inhibitor. Multivariable logistic regression models were used to assess the association of race/ethnicity, gender, and socioeconomic status with SGLT2 inhibitor use.

RESULTS

Of 934 737 patients with type 2 diabetes (mean [SD] age, 65.4 [12.9] years; 50.7% female; 57.6% White), 81 007 (8.7%) were treated with an SGLT2 inhibitor during the study period. Between 2015 and 2019, the percentage of patients with type 2 diabetes treated with an SGLT2 inhibitor increased from 3.8% to 11.9%. Among patients with type 2 diabetes and cardiovascular or kidney disease, the rate of SGLT2 inhibitor use increased but was lower than that among all patients with type 2 diabetes (HFrEF: 1.9% to 7.6%; ASCVD: 3.0% to 9.8%; CKD: 2.1% to 7.5%). In multivariable analyses, Black race (adjusted odds ratio [aOR], 0.83; 95% CI, 0.81-0.85), Asian race (aOR, 0.94; 95% CI, 0.90-0.98), and female gender (aOR, 0.84; 95% CI, 0.82-0.85) were associated with lower rates of SGLT2 inhibitor use, whereas higher median household income (≥$100 000: aOR, 1.08 [95% CI, 1.05-1.10]; $50 000-$99 999: aOR, 1.05 [95% CI, 1.03-1.07] vs <$50 000) was associated with a higher rate of SGLT2 inhibitor use. These results were similar among patients with HFrEF, ASCVD, and CKD.

CONCLUSIONS AND RELEVANCE

In this cohort study, use of an SGLT2 inhibitor treatment increased among patients with type 2 diabetes from 2015 to 2019 but remained low, particularly among patients with HFrEF, CKD, and ASCVD. Black and female patients and patients with low socioeconomic status were less likely to receive an SGLT2 inhibitor, suggesting that interventions to ensure more equitable use are essential to prevent worsening of well-documented disparities in cardiovascular and kidney outcomes in the US.

Epidemiology of end-stage kidney disease

End-stage kidney disease (ESKD) is a common and morbid disease that affects patients' quality and length of life, representing a large portion of health care expenditure in the United States. These patients commonly have associated diabetes and cardiovascular disease, with high rates of cardiovascular-related death. Management of ESKD requires renal replacement therapy via dialysis or transplantation. While transplantation provides the greatest improvement in survival and quality of life, the vast majority of patients are treated initially with hemodialysis. However, outcomes differ significantly among patient populations. Barriers in access to care have particularly affected at-risk populations, such as Black and Hispanic patients. These patients receive less pre-ESKD nephrology care, are less likely to initiate dialysis with a fistula, and wait longer for transplants-even in pediatric populations. Priorities for ESKD care moving into the future include increasing access to nephrology care in underprivileged populations, providing patient-centered care based on each patient's "life plan," and focusing on team-based approaches to ESKD care. This review explores ESKD from the perspective of epidemiology, costs, vascular access, patient-reported outcomes, racial disparities, and the impact of the COVID-19 crisis.

Increased Incidence of Chronic Kidney Injury in African Americans Following Cardiac Transplantation

OBJECTIVES

This study examined whether African American race was associated with an elevated risk of chronic kidney disease (CKD) post-cardiac transplantation.

BACKGROUND

CKD often occurs after cardiac transplantation and may require renal replacement therapy (RRT) or renal transplant. African American patients have a higher risk for kidney disease as well as worse post-cardiac transplant morbidity and mortality. It is unclear, however, if there is a propensity for African Americans to develop CKD after cardiac transplant.

METHODS

The Institutional Review Board of Columbia University Medical Center approved the retrospective study of 151 adults (57 African American and 94 non-African American) who underwent single-organ heart transplant from 2013 to 2016. The primary outcome was a decrease in estimated glomerular filtration rate (eGFR), development of CKD, and end-stage renal disease (ESRD) requiring RRT after 2 years.

RESULTS

African American patients had a significant decline in eGFR post-cardiac transplant compared to non-African American patients (- 34 ± 6 vs. - 20 ± 4 mL/min/1.73 m2, p < 0.0006). African American patients were more likely to develop CKD stage 2 or worse (eGFR < 90 mL/min/1.73 m2) than non-African American patients (81% vs. 59%, p < 0.0005).

CONCLUSIONS

This is the first study to report that African American patients are at a significantly higher risk for eGFR decline and CKD at 2 years post-cardiac transplant. Future investigation into risk reduction is necessary for this patient population.

The structural conundrum of parolees and kidney transplantation

In the United States, there are a large number of incarcerated individuals, resulting in high numbers of previously incarcerated individuals out on parole undergoing reentry into society. An aging prison population translates to an older parolee population and increased incidence of kidney disease requiring either long-term dialysis or transplantation. This paper argues that due to challenges specific to the parolee population as well as societal biases and priorities, Transplant Centers and healthcare professionals face an ethical imperative to attend to the needs of parolees as a class and take steps to address challenges related to access to Centers for renal transplantation evaluation for this disadvantaged group. It will first review the regulatory context of kidney transplantation and highlight the specific ways it effects parolees. The paper will then discuss the broader social context of parolee reentry into society and barriers faced by parolees in this process. This ethical analysis examines the complexity of these issues, and deliberates on ways to balance the competing priorities of justice, respect for this patient population as individuals and as a disadvantaged class, and the societal interests regarding organ allocation and considerable economic burdens of end-stage renal disease on parolees, the justice system, and the public.

Markers and risk factors for chronic kidney disease in sub-Saharan Africans: baseline levels and 12-month trajectories in newly referred patients in Cameroon

Background

Little is known about the changes in disease makers and risk factors in patients with chronic kidney disease (CKD) under nephrological care in Africa. This study aimed to evaluate the baseline level of markers of CKD and their 12-month time-trend in newly referred patients in a tertiary hospital in Cameroon.

Methods

This was a retrospective cohort study including 420 patients referred for CKD between 2006 and 2012 to the nephrology unit of the Douala General Hospital in the littoral region of Cameroon. Their disease and risk profile was assessed at baseline and every 3 months for 1 year. Estimated glomerular filtration rate (eGFR) was based on MDRD and Schwartz equations. CKD was diagnosed in the presence of eGFR< 60 ml/min/1.73 m² and/or proteinuria> 1+ and/or abnormal renal ultrasound persisting for ≥3 months. Data analysis used mixed linear regressions.

Results

Of the 420 patients included, 66.9% were men and mean age was 53.8 (15.1) years. At referral, 37.5% of the participants were at CKD Stage 3, 30.8% at stage 4 and 26.8% at stage 5. There was 168 (40%) diabetic and 319 (75.9%) hypertensive patients. After some improvement during the first 3 months, eGFR steadily decreased during the first year of follow-up, and this pattern was robust to adjustment for many confounders. Systolic and diastolic blood pressure levels significantly fluctuated during the first twelve months of follow-up. Changes in the levels of other risk factors and markers of disease severity over time were either borderline or non-significant.

Conclusion

Patients with CKD in African settings are referred to the nephrologist at advanced stages. This likely translates into a less beneficial effects of specialised care on the course of the disease.

Lab-based and diagnosis-based chronic kidney disease recognition and staging concordance

BACKGROUND

Chronic kidney disease (CKD) is often under-recognized and poorly documented via diagnoses, but the extent of under-recognition is not well understood among Medicare beneficiaries. The current study used claims-based diagnosis and lab data to examine patient factors associated with clinically recognized CKD and CKD stage concordance between claims- and lab-based sources in a cohort of Medicare beneficiaries.

METHODS

In a cohort of fee-for-service (FFS) beneficiaries with CKD based on 2011 labs, we examined the proportion with clinically recognized CKD via diagnoses and factors associated with clinical recognition in logistic regression. In the subset of beneficiaries with CKD stage identified from both labs and diagnoses, we examined concordance in CKD stage from both sources, and factors independently associated with CKD stage concordance in logistic regression.

RESULTS

Among the subset of 206,036 beneficiaries with lab-based CKD, only 11.8% (n = 24,286) had clinically recognized CKD via diagnoses. Clinical recognition was more likely for beneficiaries who had higher CKD stages, were non-elderly, were Hispanic or non-Hispanic Black, lived in core metropolitan areas, had multiple chronic conditions or outpatient visits in 2010, or saw a nephrologist. In the subset of 18,749 beneficiaries with CKD stage identified from both labs and diagnoses, 70.0% had concordant CKD stage, which was more likely if beneficiaries were older adults, male, lived in micropolitan areas instead of non-core areas, or saw a nephrologist.

CONCLUSIONS

There is significant under-diagnosis of CKD in Medicare FFS beneficiaries, which can be addressed with the availability of lab results.

Racial disparities in end-stage renal disease in a high-risk population: the Southern Community Cohort Study

INTRODUCTION

The Southern Community Cohort Study is a prospective study of low socioeconomic status (SES) blacks and whites from the southeastern US, where the burden of end-stage renal disease (ESRD) and its risk factors are high. We tested whether the 2.4-fold elevated risk of ESRD we previously observed in blacks compared to whites was explained by differences in baseline kidney function.

METHODS

We conducted a case-cohort study of incident ESRD cases (n = 737) with stored blood and a probability sampled subcohort (n = 4238) and calculated estimated glomerular filtration rate (eGFR) from serum creatinine. 86% of participants were enrolled from community health centers in medically underserved areas and 14% from the general population in 12 states in the southeastern United States. Incident ESRD after entry into the cohort was ascertained by linkage of the cohort with the US Renal Data System (USRDS).

RESULTS

Median (25th, 75th percentile) eGFR at baseline was 63.3 (36.0, 98.2) ml/min/1.73m2 for ESRD cases and 103.2 (86.0, 117.9) for subcohort. Black ESRD cases had higher median (25th, 75th) eGFR [63.3 (35.9, 95.9)] compared to whites [59.1 (39.4, 99.2)]. In multivariable Cox models accounting for sampling weights, baseline eGFR was a strong predictor of ESRD risk, and an interaction with race was detected (P = 0.029). The higher ESRD risk among blacks relative to whites persisted (hazard ratio: 2.58; 95% confidence interval: 1.65, 4.03) after adjustment for eGFR.

CONCLUSION

In this predominantly lower SES cohort, the racial disparity in ESRD risk is not explained by differences in baseline kidney function.

Influence of Sex on the Progression of Chronic Kidney Disease

The role that sex plays in the development and progression of chronic kidney disease remains a subject of controversy. The lack of clarity in this important area reflects complex interactions between biological factors and cultural and socioeconomic influences that impact the relationship between sex and renal disease. Certainly, additional observational studies are indicated; however, innovative approaches are required to isolate biological processes from cultural influences. Despite these limitations, available data suggest that the progression of renal disease is slower in women than in men and that this sexual dimorphism is primarily due to direct actions of sex hormones on cellular metabolism. The extent to which differences in lifestyle factors between the sexes influence sexual dimorphism in the progression of chronic kidney disease remains to be elucidated.

Cost of chronic kidney disease attributable to diabetes from the perspective of the Brazilian Unified Health System

INTRODUCTION

Diabetes is the most common cause of chronic kidney disease, with a high economic impact on health systems.

OBJECTIVE

To estimate the cost of chronic kidney disease (CKD) and end-stage kidney disease (ESKD) attributable to diabetes, stratified by sex, race/skin color, and age, from the perspective of the Brazilian public health system between 2010 and 2016.

METHODS

Population attributable risk (PAR) was calculated from the Brazilian prevalence of diabetes and the relative risk (or odds ratio) of persons with diabetes developing CKD and ESKD as compared to non-diabetic subjects. The variables of interest were sex, race/skin color, and age. A top-down approach was used to measure the direct costs of the disease reimbursed by the Brazilian Ministry of Health, using data from outpatient and inpatient records.

RESULTS

The cost of CKD and ESKD attributable to diabetes in the period 2010-2016 was US$1.2 billion (US$180 million per year) and trending upward. Female sex, age 65-75, and black race/skin color contributed substantially to the costs of CKD and ESKD (US$475 million, US$63 million, and US$25 million respectively). The clinical procedures accounting for the greatest share of disease-attributable costs are hemodialysis and peritoneal dialysis.

CONCLUSION

Diabetes accounted for 22% of the costs of CKD and ESKD. Female sex, age 65-75 years, and black race/skin color were the variables which contributed most to disease-related expenditure. The economic burden of CKD may increase gradually in the coming years, with serious implications for the financial sustainability of the Brazilian public health system.

ESRD among Immigrants to Ontario, Canada: A Population-Based Study

Background The epidemiology of ESRD requiring maintenance dialysis (ESRD-D) in large, diverse immigrant populations is unclear.Methods We estimated ESRD-D prevalence and incidence among immigrants in Ontario, Canada. Adults residing in Ontario in 2014 were categorized as long-term Canadian residents or immigrants according to administrative health and immigration datasets. We determined ESRD-D prevalence among these adults and calculated age-adjusted prevalence ratios (PRs) comparing immigrants to long-term residents. Among those who immigrated to Ontario between 1991 and 2012, age-adjusted ESRD-D incidence was calculated by world region and country of birth, with immigrants from Western nations as the referent group.Results Among 1,902,394 immigrants and 8,860,283 long-term residents, 1700 (0.09%) and 8909 (0.10%), respectively, presented with ESRD-D. Age-adjusted ESRD-D prevalence was higher among immigrants from sub-Saharan Africa (PR, 2.17; 95% confidence interval [95% CI], 1.84 to 2.57), Latin America and the Caribbean (PR, 2.11; 95% CI, 1.90 to 2.34), South Asia (PR, 1.45; 95% CI, 1.32 to 1.59), and East Asia and the Pacific (PR, 1.34; 95% CI, 1.22 to 1.46). Immigrants from Somalia (PR, 4.18; 95% CI, 3.11 to 5.61), Trinidad and Tobago (PR, 2.88; 95% CI, 2.23 to 3.73), Jamaica (PR, 2.88; 95% CI, 2.40 to 3.44), Sudan (PR, 2.84; 95% CI, 1.53 to 5.27), and Guyana (PR, 2.69; 95% CI, 2.19 to 3.29) had the highest age-adjusted ESRD-D PRs relative to long-term residents. Immigrants from these countries also exhibited higher age-adjusted ESKD-D incidence relative to Western Nations immigrants.Conclusions Among immigrants in Canada, those from sub-Saharan Africa and the Caribbean have the highest ESRD-D risk. Tailored kidney-protective interventions should be developed for these susceptible populations.

Race, Genomics and Chronic Disease: What Patients with African Ancestry Have to Say

BACKGROUND

Variants of the APOL1 gene increase risk for kidney failure 10-fold, and are nearly exclusively found in people with African ancestry. To translate genomic discoveries into practice, we gathered information about effects and challenges incorporating genetic risk in clinical care.

METHODS

An academic-community-clinical team tested 26 adults with self-reported African ancestry for APOL1 variants, conducting in-depth interviews about patients' beliefs and attitudes toward genetic testing- before, immediately, and 30 days after receiving test results. We used constant comparative analysis of interview transcripts to identify themes.

RESULTS

Themes included: Knowledge of genetic risk for kidney failure may motivate providers and patients to take hypertension more seriously, rather than inspiring fatalism or anxiety. Having genetic risk for a disease may counter stereotypes of Blacks as non-adherent or low-literate, rather than exacerbate stereotypes.

CONCLUSION

Populations most likely to benefit from genomic research can inform strategies for genetic testing and future research.

Sex and gender disparities in the epidemiology and outcomes of chronic kidney disease

Improved understanding of sex and gender-specific differences in the aetiology, mechanisms and epidemiology of chronic kidney disease (CKD) could help nephrologists better address the needs of their patients. Population-based studies indicate that CKD epidemiology differs by sex, affecting more women than men, especially with regard to stage G3 CKD. The effects of longer life expectancy on the natural decline of glomerular filtration rate (GFR) with age, as well as potential overdiagnosis of CKD through the inappropriate use of GFR equations, might be in part responsible for the greater prevalence of CKD in women. Somewhat paradoxically, there seems to be a preponderance of men among patients starting renal replacement therapy (RRT); the protective effects of oestrogens in women and/or the damaging effects of testosterone, together with unhealthier lifestyles, might cause kidney function to decline faster in men than in women. Additionally, elderly women seem to be more inclined to choose conservative care instead of RRT. Dissimilarities between the sexes are also apparent in the outcomes of CKD. In patients with predialysis CKD, mortality is higher in men than women; however, this difference disappears for patients on RRT. Although access to living donor kidneys among men and women seems equal, women have reduced access to deceased donor transplantation. Lastly, health-related quality of life while on RRT is poorer in women than men, and women report a higher burden of symptoms. These findings provide insights into differences in the underlying pathophysiology of disease as well as societal factors that can be addressed to reduce disparities in access to care and outcomes for patients with CKD.

Sex and gender disparities in the epidemiology and outcomes of chronic kidney disease

Improved understanding of sex and gender-specific differences in the aetiology, mechanisms and epidemiology of chronic kidney disease (CKD) could help nephrologists better address the needs of their patients. Population-based studies indicate that CKD epidemiology differs by sex, affecting more women than men, especially with regard to stage G3 CKD. The effects of longer life expectancy on the natural decline of glomerular filtration rate (GFR) with age, as well as potential overdiagnosis of CKD through the inappropriate use of GFR equations, might be in part responsible for the greater prevalence of CKD in women. Somewhat paradoxically, there seems to be a preponderance of men among patients starting renal replacement therapy (RRT); the protective effects of oestrogens in women and/or the damaging effects of testosterone, together with unhealthier lifestyles, might cause kidney function to decline faster in men than in women. Additionally, elderly women seem to be more inclined to choose conservative care instead of RRT. Dissimilarities between the sexes are also apparent in the outcomes of CKD. In patients with predialysis CKD, mortality is higher in men than women; however, this difference disappears for patients on RRT. Although access to living donor kidneys among men and women seems equal, women have reduced access to deceased donor transplantation. Lastly, health-related quality of life while on RRT is poorer in women than men, and women report a higher burden of symptoms. These findings provide insights into differences in the underlying pathophysiology of disease as well as societal factors that can be addressed to reduce disparities in access to care and outcomes for patients with CKD.

Lessons from CKD-Related Genetic Association Studies-Moving Forward

Over the past decade, genetic association studies have uncovered numerous determinants of kidney function in the general, diabetic, hypertensive, CKD, ESRD, and GN-based study populations (e.g., IgA nephropathy, membranous nephropathy, FSGS). These studies have led to numerous novel and unanticipated findings, which are helping improve our understanding of factors and pathways affecting both normal and pathologic kidney function. In this review, we report on major discoveries and advances resulting from this rapidly progressing research domain. We also predict some of the next steps the nephrology community should embrace to accelerate the identification of genetic and molecular processes leading to kidney dysfunction, pathophysiologically based disease subgroups, and specific therapeutic targets, as we attempt to transition toward a more precision-based medicine approach.

Incidence of chronic kidney disease among people with diabetes: a systematic review of observational studies

AIMS

The aim was to systematically review published articles that reported the incidence of chronic kidney disease among people with diabetes.

METHODS

A systematic literature search was performed using MEDLINE, Embase and CINAHL databases. The titles and abstracts of all publications identified by the search were reviewed and 10 047 studies were retrieved.

RESULTS

A total of 71 studies from 30 different countries with sample sizes ranging from 505 to 211 132 met the inclusion criteria. The annual incidence of microalbuminuria and albuminuria ranged from 1.3% to 3.8% for Type 1 diabetes. For Type 2 diabetes and studies combining both diabetes types, the range was from 3.8% to 12.7%, with four of six studies reporting annual rates between 7.4% and 8.6%. In studies reporting the incidence of eGFR < 60 ml/min/1.73 m² using the Modification of Diet on Renal Disease (MDRD) equation, apart from one study which reported an annual incidence of 8.9%, the annual incidence ranged from 1.9% to 4.3%. The annual incidence of end-stage renal disease ranged from 0.04% to 1.8%.

CONCLUSIONS

The annual incidence of microalbuminuria and albuminuria is ~ 2-3% in Type 1 diabetes, and ~ 8% in Type 2 diabetes or mixed diabetes type. The incidence of developing eGFR < 60 ml/min/1.73 m² is ~ 2-4% per year. Despite the wide variation in methods and study design, within a particular category of kidney disease, there was only modest variation in incidence rates. These findings may be useful in clinical settings to help understand the risk of developing kidney disease among those with diabetes.

End stage renal disease in French Guiana (data from R.E.I.N registry): South American or French?

BACKGROUND

End-Stage renal disease (ESRD) causes considerable morbidity and mortality, and significantly alters patients' quality of life. There are very few published data on this problem in the French Overseas territories. The development of a registry on end stage renal disease in French Guiana in 2011 allowed to describe the magnitude of this problem in the region for the first time.

METHODS

Using data from the French Renal Epidemiology and Information Network registry (R.E.I.N). Descriptive statistics on quantitative and qualitative variables in the registry were performed on prevalent cases and incident cases in 2011, 2012 and 2013.

RESULTS

French Guiana has one of the highest ESRD prevalence and incidence in France. The two main causes of ESRD were hypertensive and diabetic nephropathies. The French Guianese population had a different demographic profile (younger, more women, more migrants) than in mainland France. Most patients had at least one comorbidity, predominantly (95.3%) hypertension. In French Guiana dialysis was initiated in emergency for 71.3% of patients versus 33% in France (p < 0.001).

CONCLUSION

These first results give important public health information: i) End stage renal disease has a very high prevalence relative to mainland France ii) Patients have a different demographic profile and enter care late in the course of their renal disease. These data are closer to what is observed in the Caribbean or in Latin America than in Mainland France.

Integrating APOL1 Gene Variants Into Renal Transplantation: Considerations Arising From the American Society of Transplantation Expert Conference

Thirteen percent of individuals of African ancestry express two variant copies of the gene encoding apolipoprotein 1 (APOL1) that has been associated with an increased risk of end-stage renal disease (ESRD) in the general population. Limited studies suggest that the survival of transplanted kidneys from donors expressing two APOL1 risk alleles is inferior to that of kidneys from donors with zero or one risk allele. In living kidney donation, two case reports describe donors expressing two APOL1 risk alleles who developed ESRD. Given the potential impact of APOL1 variants on the utility and safety of kidney transplantation and living kidney donation, the American Society of Transplantation convened a meeting with the goals of summarizing the current state of knowledge with respect to transplantation and APOL1, identifying knowledge gaps and studies to address these gaps, and considering approaches to integrating APOL1 into clinical practice. The authors recognize that current data are not sufficient to support traditional evidence-based guidelines but also recognize that it may require several years to generate the necessary data. Thus, approaches as to how APOL1 might currently be integrated into the clinical decision-making process were considered. This report summarizes the group's deliberations.

Diabetes mellitus as a risk factor for incident chronic kidney disease and end-stage renal disease in women compared with men: a systematic review and meta-analysis

Diabetes mellitus is a strong risk factor for chronic kidney disease and end-stage renal disease. Whether sex differences in chronic kidney disease and end-stage renal disease incidence exist among diabetic patients remains unclear. This systematic review and meta-analysis was conducted to evaluate the relative effect of diabetes on chronic kidney disease and end-stage renal disease risk in women compared with men. We systematically searched Embase, PubMed, and the Cochrane Library for both cohort and case-control studies until October 2015. Studies were selected if they reported a sex-specific relationship between diabetes mellitus and chronic kidney disease or end-stage renal disease. We generated pooled estimates across studies using random-effects meta-analysis after log transformation with inverse variance weighting. Ten studies with data from more than 5 million participants were included. The pooled adjusted risk ratio of chronic kidney disease associated with diabetes mellitus was 3.34 (95 % CI 2.27, 4.93) in women and 2.84 (95 % CI 1.73, 4.68) in men. The data showed no difference in diabetes-related chronic kidney disease risk between the sexes (pooled adjusted women-to-men relative risk ratio was 1.14 [95 % CI 0.97, 1.34]) except for end-stage renal disease-the pooled adjusted women-to men relative risk ratio was 1.38 (95 % CI 1.22, 1.55; p = 0.114, I² = 38.1 %). The study found no evidence of a sex difference in the association between diabetes mellitus and chronic kidney disease. However, the excess risk for end-stage renal disease was higher in women with diabetes than in men with the same condition, from which we assume that the female gender could accelerate the disease progression. Further studies are needed to support this notion and elucidate the underlying mechanisms.

Racial Differences in Survival of Incident Home Hemodialysis and Kidney Transplant Patients

BACKGROUND

Previous studies have indicated that patients on maintenance hemodialysis have worse survival compared with kidney transplant (KTx) recipients. However, none of these studies have compared mortality of the US patients using alternative dialysis modalities such as home hemodialysis (HHD) with KTx recipients.

METHODS

Comparing patients who started HHD with those who received kidney transplantation in the United States between 2007 and 2011, we created a 1:1 propensity score-matched cohort of 4000 patients and examined the association between treatment modality and all-cause mortality using Cox proportional hazard models.

RESULTS

The mean ± SD age of the propensity score-matched HHD and KTx patients at baseline were 54 ± 15 years and 54 ± 14 years, 65% were men (both groups), 70% and 72% of patients were whites, and 19% were African American (both groups), respectively. Over 5 years of follow-up, HHD patients had 4 times higher mortality risk compared with KTx recipients in the entire patient population (hazard ratio [HR], 4.06; 95% confidence interval [95% CI], 3.27-5.04); total event number, 411), and similar difference was found across each race stratum. However, during the first year of therapy, although the white HHD patients had higher mortality risk (HR, 4.21; 95% CI, 3.10-5.73; total event number, 332) compared with their KTx counterparts, there was no significant difference in mortality risk between African American HHD and KTx patients (HR, 1.62; 95% CI, 0.77-3.39; total event number, 55). This result was consistent across different types of kidney donors.

CONCLUSIONS

The HHD patients appear to have 4 times higher mortality compared with KTx recipients regardless of the type of kidney donor. Further studies are needed to understand the reasons underlying racial differenes during the first year of therapy.

Trans-ethnic Fine Mapping Highlights Kidney-Function Genes Linked to Salt Sensitivity

We analyzed genome-wide association studies (GWASs), including data from 71,638 individuals from four ancestries, for estimated glomerular filtration rate (eGFR), a measure of kidney function used to define chronic kidney disease (CKD). We identified 20 loci attaining genome-wide-significant evidence of association (p < 5 × 10(-8)) with kidney function and highlighted that allelic effects on eGFR at lead SNPs are homogeneous across ancestries. We leveraged differences in the pattern of linkage disequilibrium between diverse populations to fine-map the 20 loci through construction of "credible sets" of variants driving eGFR association signals. Credible variants at the 20 eGFR loci were enriched for DNase I hypersensitivity sites (DHSs) in human kidney cells. DHS credible variants were expression quantitative trait loci for NFATC1 and RGS14 (at the SLC34A1 locus) in multiple tissues. Loss-of-function mutations in ancestral orthologs of both genes in Drosophila melanogaster were associated with altered sensitivity to salt stress. Renal mRNA expression of Nfatc1 and Rgs14 in a salt-sensitive mouse model was also reduced after exposure to a high-salt diet or induced CKD. Our study (1) demonstrates the utility of trans-ethnic fine mapping through integration of GWASs involving diverse populations with genomic annotation from relevant tissues to define molecular mechanisms by which association signals exert their effect and (2) suggests that salt sensitivity might be an important marker for biological processes that affect kidney function and CKD in humans.

End-stage renal disease in patients with rheumatoid arthritis

OBJECTIVES

To determine the frequency of end-stage renal disease (ESRD) in patients with rheumatoid arthritis (RA), the causes of ESRD, and the treatment of RA in the setting of ESRD.

METHODS

Cross-sectional study of RA (N = 3754) and non-RA (N = 326,776) patients in the United States Renal Data System (USRDS) during 2011 (N = 330,530). The epidemiology of ESRD in RA was determined and the etiology of ESRD in patients with and without RA was compared. The frequency of patients with RA with at least one filled prescription for prednisone/prednisolone, a DMARD, and/or a biologic in 2011 was determined.

RESULTS

The prevalence of RA with ESRD in the USRDS in 2011 was 1.1%. There were significant differences in age, race, sex, and BMI category between the groups (p < 0.01). Diabetes (33.5%) and hypertension (30.6%) were the most common primary causes of ESRD in patients with RA. Amyloidosis, vasculitis, and analgesic nephropathy combined accounted for less than 10% of cases of ESRD. Prednisone was the most commonly filled medication that could be used to treat RA (45.9% of RA patients). Hydroxychloroquine was the most frequently filled DMARD (13.5%); biologics were uncommon (etanercept 2.5%, adalimumab 1.5%; golimumab, infliximab, anakinra, and abatacept <1%).

CONCLUSIONS

The co-occurrence of RA with ESRD was 1.1% in the USRDS by 2011. Physicians should be aware of the critical impact of the comorbidities of diabetes and hypertension in causing ESRD in RA patients. Use of DMARDS other than hydroxychloroquine and biologics to treat RA in the setting of ESRD appears to be infrequent. Further prospective studies of treatment strategies for RA in ESRD are needed.

Increased body mass index may be associated with greater risk of end-stage renal disease in whites compared to blacks: A nested case-control study

BACKGROUND

The relationship between body mass index (BMI) and end-stage renal disease (ESRD) may differ between blacks and whites due to underlying metabolic differences.

METHODS

We conducted a nested case-control study of 631 incident ESRD cases and 1,897 matched controls within the Southern Community Cohort Study. Current weight, height, and weight at age 21 were reported at enrollment. Occurrence of ESRD was ascertained by linkage with the United States Renal Data System. With normal BMI (18.5-24.9 kg/m²) as reference, conditional logistic regression was used to calculate adjusted odds ratios (OR) and corresponding 95% confidence intervals (CI) for ESRD across other BMI categories by race. In subsequent analysis, BMI at age 21 was modeled using restricted cubic splines with 5 knots. Predicted probabilities of incident ESRD were computed from the multivariable logistic models and plotted against BMI at age 21.

RESULTS

Among blacks, odds of ESRD were significantly increased among those who were overweight (OR: 1.41; 95%CI: 1.09, 1.83) or obese (OR: 2.56; 95%CI: 1.88, 3.47) at age 21. Among whites, the association between ESRD and BMI at age 21 was more pronounced, with corresponding ORs of 2.13 (95%CI: 0.92, 4.93) and 7.46 (95%CI: 2.90, 19.21; p-interaction 0.05). Only among whites was high BMI at enrollment associated with ESRD risk; OR for BMI≥40 kg/m², was 3.31 (95%CI: 1.08, 10.12). The plot of the predicted probabilities of incident ESRD vs BMI at age 21 showed a monotonic increase in the probability of ESRD after a BMI cutoff ≈ 25Kg/m² in both whites and blacks but the slope of the curve for whites appeared greater.

CONCLUSIONS

Our results suggest racial differences in the relationship between BMI, both in early adulthood and middle age, and ESRD. These findings warrant further research into understanding the underlying metabolic differences that may explain these differences.

Disparities in Electronic Health Record Patient Portal Use in Nephrology Clinics

BACKGROUND AND OBJECTIVES

Electronic health record (EHR) patient portals allow individuals to access their medical information with the intent of patient empowerment. However, little is known about portal use in nephrology patients. We addressed this gap by characterizing adoption of an EHR portal, assessing secular trends, and examining the association of portal adoption and BP control (<140/90 mmHg).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients seen between January 1, 2010, and December 31, 2012, at any of four university-affiliated nephrology offices who had at least one additional nephrology follow-up visit before June 30, 2013, were included. Sociodemographic characteristics, comorbidities, clinical measurements, and office visits were abstracted from the EHR. Neighborhood median household income was obtained from the American Community Survey 2012.

RESULTS

Of 2803 patients, 1098 (39%) accessed the portal. Over 87% of users reviewed laboratory results, 85% reviewed their medical information (e.g., medical history), 85% reviewed or altered appointments, 77% reviewed medications, 65% requested medication refills, and 31% requested medical advice from their renal provider. In adjusted models, older age, African-American race (odds ratio [OR], 0.50; 95% confidence interval [95% CI], 0.39 to 0.64), Medicaid status (OR, 0.53; 95% CI, 0.36 to 0.77), and lower neighborhood median household income were associated with not accessing the portal. Portal adoption increased over time (2011 versus 2010: OR, 1.38 [95% CI, 1.09 to 1.75]; 2012 versus 2010: OR, 1.95 [95% CI, 1.44 to 2.64]). Portal adoption was correlated with BP control in patients with a diagnosis of hypertension; however, in the fully adjusted model this was somewhat attenuated and no longer statistically significant (OR, 1.11; 95% CI, 0.99 to 1.24).

CONCLUSION

While portal adoption appears to be increasing, greater attention is needed to understand why vulnerable populations do not access it. Future research should examine barriers to the use of e-health technologies in underserved patients with CKD, interventions to address them, and their potential to improve outcomes.

Association of depressive and anxiety symptoms with adverse events in Dutch chronic kidney disease patients: a prospective cohort study

Background

Depressive symptoms have been reported to be associated with adverse clinical outcome in patients with chronic kidney disease (CKD) not on dialysis. This association has not been examined in Europe. Anxiety and depressive symptoms often co-occur. However, as yet there are no data concerning a possible association of anxiety symptoms with adverse clinical outcome. We examined the association of depressive and anxiety symptoms with adverse clinical outcome in Dutch CKD patients not on dialysis.

Methods

In this 3-year follow-up prospective cohort study, CKD patients not on dialysis with an estimated glomerular filtration rate (eGFR) ≤ 35 ml/min/1.73 m² from an urban teaching hospital were selected. Symptoms of depression and anxiety were evaluated using the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). Cox proportional hazards models were used to calculate hazard ratio’s (HRs) with a composite event of death, initiation of dialysis, and hospitalization as outcome. HRs were adjusted for age, gender, diabetes, cardiovascular disease and eGFR.

Results

Of 100 included CKD patients depressive and anxiety symptoms were present in 34 and 31 %, respectively. Adjusted HRs for the composite event for patients with depressive and anxiety symptoms were 2.0 (95 % confidence interval (CI) 1.2–3.5) and 1.6 (95 % CI 0.9–2.7), respectively. Twenty three patients had both depressive and anxiety symptoms of whom adjusted HRs were 2.2 (95 % CI 1.2–4.0) for a composite event.

Conclusions

Depressive and anxiety symptoms are common in patients with CKD in The Netherlands. Depressive symptoms are associated with an increased risk of poor clinical outcome. Anxiety symptoms show a trend for an increased risk of poor clinical outcome. There seems to be no additive effect of anxiety symptoms in addition to depressive symptoms with regard to poor clinical outcome.

Adiposity patterns and the risk for ESRD in postmenopausal women

BACKGROUND AND OBJECTIVES

Body mass index and waist circumference associate with adverse health outcomes, including CKD. Studies of the association of body mass index and ESRD have been inconsistent; these adiposity measures have not been previously assessed together for ESRD risk or among postmenopausal women.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

This was prospective cohort study of 20,117 postmenopausal women enrolled in the multiethnic cohort of the Women's Health Initiative. Body mass index and waist circumference were obtained at baseline, incident ESRD was obtained from the US Renal Data System, and all-cause death was obtained from surveillance data. A competing-risk framework was used to account for the effect of mortality before ESRD while adjusting for significant predictors and baseline kidney function. Associations of adiposity with mortality were also studied.

RESULTS

Events included 212 patients with incident ESRD and 3104 deaths for a mean follow-up of 11.6 years. Increased waist circumference and body mass index were associated with 2.59- (95% confidence interval, 1.89 to 3.53) and 1.97-fold (95% confidence interval, 1.30 to 2.98) higher hazards of ESRD as well as 1.42- (95% confidence interval, 1.32 to 1.53) and 1.21-fold (95% confidence interval, 1.11 to 1.33) higher hazards of death, respectively, compared with the lower categories in adjusted analyses. The associations of waist circumference with ESRD varied by baseline renal function (P for interaction=0.01) and were significant only among women without baseline eGFR-defined CKD (hazard ratio, 1.93; 95% confidence interval, 1.23 to 3.03).

CONCLUSIONS

Central obesity was associated with an increased risk of ESRD in postmenopausal women, even among women with normal body mass index but not among women with reduced baseline kidney function, and an increased risk of death. Body mass index was associated with ESRD, and the association is likely mediated through hypertension and diabetes.

Incidence of end stage renal disease among type 1 diabetes: a nationwide cohort study in Taiwan

The aim of our study was to estimate the risk of end-stage renal disease (ESRD) in type 1 diabetes mellitus (T1DM) in Taiwanese people; in addition, our goal was to determine how the age, year, and sex at registration of T1DM affects the risk. Population-based cohort study. A nationwide cohort study of 7203 Taiwanese patients with T1DM registered in 1999 to 2010 was followed up until ESRD, death, or the end of follow-up on December 31, 2010. Annual age-, sex-, and calendar year-specific incidence rates of ESRD of the general population were used to calculate the standardized incidence ratio (SIR) of ESRD in relation to T1DM. The SIR of ESRD for male and female patients with T1DM was significantly increased at 25.85 (95% CI 23.40-28.29) and 28.08 (95% 25.45-30.71), respectively; the peak was at age 15 to 29 years for both genders. The cumulative incidence of ESRD was similar in male and female patients but was significantly higher in patients≥ 30 years old than in patients<30 years old (10.25% vs. 3.57%, P<0.001). Patients aged <15 years had a significantly lower risk of ESRD as compared to those aged 15 to 29 years; patients aged 30 to 44 (adjusted HR, 1.491) and 45 to 60 years (adjusted HR, 2.111) showed significantly increased hazards. Our data also demonstrated a lower risk of ESRD in patients who were registered in later years than in earlier years. The risk of ESRD is substantially increased in T1DM in the ethnic Chinese population. The continuously declining risk of ESRD in T1DM may advocate the use of a multidisciplinary chronic kidney disease care system in Taiwan.

Estimating time to ESRD using kidney failure risk equations: results from the African American Study of Kidney Disease and Hypertension (AASK)

BACKGROUND

Planning for renal replacement therapy, such as referral for arteriovenous fistula placement and transplantation, often is guided by level of estimated glomerular filtration rate (eGFR). The use of risk equations might enable more accurate estimation of time to end-stage renal disease (ESRD), thus improving patient care.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

1,094 participants in the African American Study of Kidney Disease and Hypertension (AASK) cohort.

PREDICTOR

Age, sex, urine protein-creatinine ratio ≥ 1g/g, APOL1 high-risk status, and 3-year antecedent eGFR decline.

OUTCOME

Cumulative incidence of ESRD from 5 different starting points: eGFR of 30 and 15mL/min/1.73m(2) and 1-year ESRD risk of 5%, 10%, and 20%, estimated by a published 4-variable kidney failure risk equation.

RESULTS

566 participants developed eGFR of 30mL/min/1.73m(2), 244 developed eGFR of 15mL/min/1.73m(2), and 437, 336, and 259 developed 1-year ESRD risks of 5%, 10%, and 20%, respectively. The 1-year cumulative incidence of ESRD was 4.3% from eGFR of 30mL/min/1.73m(2), 49.0% from eGFR of 15mL/min/1.73m(2), 6.7% from 5% ESRD risk, 15.0% from 10% ESRD risk, and 29% from 20% ESRD risk. From eGFR of 30mL/min/1.73m(2), there were several risk factors that predicted ESRD risk. From eGFR of 15mL/min/1.73m(2), only level of proteinuria did; median time to ESRD was 9 and 19 months in those with higher and lower proteinuria, respectively. Median times were less variable from corresponding ESRD risk thresholds. For example, median times to ESRD from 20% ESRD risk were 22 and 25 months among those with higher and lower proteinuria, respectively.

LIMITATIONS

Relatively homogeneous population of African Americans with hypertensive kidney disease.

CONCLUSIONS

Results of the present study suggest the potential benefit of incorporating kidney failure risk equations into clinical care, with selection of a specific threshold guided by its intended use.

Raising awareness of acute kidney injury: a global perspective of a silent killer

Worldwide, acute kidney injury (AKI) is associated with poor patient outcomes. Over the last few years, collaborative efforts, enabled by a common definition of AKI, have provided a description of the epidemiology, natural history, and outcomes of this disease and improved our understanding of the pathophysiology. There is increased recognition that AKI is encountered in multiple settings and in all age groups, and that its course and outcomes are influenced by the severity and duration of the event. The effect of AKI on an individual patient and the resulting societal burden that ensues from the long-term effects of the disease, including development of chronic kidney disease (CKD) and end-stage renal disease (ESRD), is attracting increasing scrutiny. There is evidence of marked variation in the management of AKI, which is, to a large extent, due to a lack of awareness and an absence of standards for prevention, early recognition, and intervention. These emerging data point to an urgent need for a global effort to highlight that AKI is preventable, its course is modifiable, and its treatment can improve outcomes. In this article, we provide a framework of reference and propose specific strategies to raise awareness of AKI globally, with the goal to ultimately improve outcomes from this devastating disease.

Differences in progression to ESRD between black and white patients receiving predialysis care in a universal health care system

BACKGROUND AND OBJECTIVES

Studies performed in the United States showed that blacks progress from CKD to ESRD faster than do whites. Possible explanations are differences in health care system factors. This study investigated whether progression is also faster in a universal health care system, where all patients receive comparable care.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the PREdialysis PAtient REcord study, a multicenter follow-up study of patients with CKD who started predialysis care in The Netherlands (1999-2011), were analyzed. Time-dependent Cox proportional hazards models were used to estimate the hazard ratio (HR) for starting renal replacement therapy (RRT), and linear mixed models were used to compare renal function decline (RFD) between blacks and whites. To explore possible mechanisms, analyses were adjusted for patient characteristics.

RESULTS

At initiation of predialysis care, blacks (n=49) were younger and had more diabetes mellitus, higher proteinuria levels, and a higher estimated GFR than whites (n=946). Median follow-up time in months was similar (blacks: 13.9 [boundaries of interquartile range (IQR), 5.3 to 19.5]; whites: 13.1 [IQR, 5.1 to 24.0]). For blacks compared with whites, the crude HR for starting RRT within the first 15 months was 0.86 (95% confidence interval [CI], 0.55 to 1.34) and from 15 months onward, 1.93 (95% CI, 1.02 to 3.68), which increased after adjustment. RFD was faster by 0.18 (95% CI, 0.05 to 0.32) ml/min per 1.73 m(2) per month in blacks compared with whites.

CONCLUSION

Blacks receiving predialysis care in a universal health care system have faster disease progression than whites, suggesting that health care system factors have a less influential role than had been thought in explaining black-white differences.

Smoking and risk of kidney failure in the Singapore Chinese health study

Background

The relationship between smoking and risk of kidney failure, especially in people of Chinese origin, is not clear. We analyzed data from the Singapore Chinese Health Study to investigate whether smoking increases the risk of kidney failure.

Methods

The Singapore Chinese Health Study is a population-based cohort of 63,257 Chinese adults enrolled between 1993 and 1998. Information on smoking status was collected at baseline. Incidence of kidney failure was identified via record linkage with the nationwide Singapore Renal Registry until 2008. Kidney failure was defined by one of the following: 1) serum creatinine level of more than or equal to 500 µmol/l (5.7 mg/dl), 2) estimated glomerular filtration rate of less than 15 ml/min/1.73 m², 3) undergoing hemodialysis or peritoneal dialysis, 4) undergone kidney transplantation. Cox proportional hazard regression analysis was performed for the outcome of kidney failure after adjusting for age, education, dialect, herbal medications, body mass index, sex, physician-diagnosed hypertension and diabetes mellitus.

Results

The mean age of subjects was 55.6 years at baseline, and 44% were men. Overall 30.6% were ever smokers (current or former) at baseline. A total of 674 incident cases of kidney failure occurred during a median follow-up of 13.3 years. Among men, smokers had a significant increase in the adjusted risk of kidney failure [hazard ratio (HR): 1.29; 95% CI: 1.02–1.64] compared to never smokers. There was a strong dose-dependent association between number of years of smoking and kidney failure, (p for trend = 0.011). The risk decreased with prolonged cessation (quitting ≥10 years since baseline). The number of women smokers was too few for conclusive relationship.

Limitation

Information on baseline kidney function was not available.

Conclusions

Cigarette smoking is associated with increased risk of kidney failure among Chinese men. The risk appears to be dose- and duration-dependent and modifiable after long duration of cessation.

Progress in the development of animal models of acute kidney injury and its impact on drug discovery

INTRODUCTION

Acute kidney injury (AKI) is a clinical syndrome characterized by the acute loss of kidney function. AKI is increasingly frequent and is associated with impaired survival and chronic kidney disease progression. Experimental AKI models have contributed to a better understanding of pathophysiological mechanisms but they have not yet resulted in routine clinical application of novel therapeutic approaches.

AREAS COVERED

The authors present the advances in experimental AKI models over the last decade. Furthermore, the authors review their current and expected impact on novel drug discovery.

EXPERT OPINION

New AKI models have been developed in rodents and non-rodents. Non-rodents allow the evaluation of specific aspects of AKI in both bigger animals and simpler organisms such as drosophila and zebrafish. New rodent models have recently reproduced described clinical entities, such as aristolochic and warfarin nephropathies, and have also provided better models for old entities such as thrombotic microangiopathy-induced AKI. Several therapies identified in animal models are now undergoing clinical trials in human AKI, including p53 RNAi and bone-marrow derived mesenchymal stem cells. It is conceivable that further refinement of animal models in combination with ongoing trials and novel trials based on already identified potential targets will eventually yield effective therapies for clinical AKI.

Association of race and body mass index with ESRD and mortality in CKD stages 3-4: results from the Kidney Early Evaluation Program (KEEP)

BACKGROUND

A recent cross-sectional analysis of Kidney Early Evaluation Program (KEEP) participants suggested that obesity is a heterogeneous disease state in African Americans and whites with chronic kidney disease (CKD).

STUDY DESIGN

In longitudinal analyses spanning 8 years of follow-up, we examined whether race and body mass index (BMI) influence end-stage renal disease (ESRD) and mortality rates in participants with CKD stages 3-4.

SETTING & PARTICIPANTS

KEEP participants were included in this analysis if they met the following criteria: (1) estimated glomerular filtration rate (eGFR) of 15-59 mL/min/1.73 m(2), (2) white or African American race, and (3) no previous dialysis or transplantation.

OUTCOMES & MEASUREMENTS

Survival analyses were performed for the outcomes of ESRD, death, and combined outcome of ESRD or death.

RESULTS

Of 14,631 participants with CKD stages 3-4, 28% were African American and 72% were white. African American participants had higher rates of obesity and hypertension, with a higher baseline mean eGFR, higher prevalence of albuminuria, and greater degree of anemia compared with whites. In multivariable models, African American race increased the risk of ESRD (HR, 1.66; 95% CI, 1.26-2.07), but not death (HR, 0.89; 95% CI, 0.76-1.03). In these models, male sex, hypertension, diabetes, lower baseline eGFR, and albuminuria were predictive of higher rates of ESRD; age, male sex, diabetes, lower baseline eGFR, and albuminuria were predictive of overall mortality. There was no significant interaction between race and BMI in the adjusted model for outcomes of ESRD (P = 0.7) or death (P = 0.3).

LIMITATIONS

Baseline values used in the analysis are from a cross-sectional data set. Dyslipidemia and secondary hyperparathyroidism were not accounted for in the analysis.

CONCLUSIONS

African American race was associated with a higher incidence of ESRD, but not mortality. Although obesity may be a heterogeneous disease state in African Americans and whites with CKD, there does not appear to be a significant interaction between race and BMI in progression to ESRD or death.