Chronic kidney disease prevalence estimates among racial/ethnic groups: the Multi-Ethnic Study of Atherosclerosis

Structural and social determinants of health: The multi-ethnic study of atherosclerosis

BACKGROUND

Researchers have increasingly recognized the importance of structural and social determinants of health (SSDOH) as key drivers of a multitude of diseases and health outcomes. The Multi-Ethnic Study of Atherosclerosis (MESA) is an ongoing, longitudinal cohort study of subclinical cardiovascular disease (CVD) that has followed geographically and racially/ethnically diverse participants starting in 2000. Since its inception, MESA has incorporated numerous SSDOH assessments and instruments to study in relation to CVD and aging outcomes. In this paper, we describe the SSDOH data available in MESA, systematically review published papers using MESA that were focused on SSDOH and provide a roadmap for future SSDOH-related studies.

METHODS AND FINDINGS

The study team reviewed all published papers using MESA data (n = 2,125) through January 23, 2023. Two individuals systematically reviewed titles, abstracts, and full text to determine the final number of papers (n = 431) that focused on at least one SSDOH variable as an exposure, outcome, or stratifying/effect modifier variable of main interest (discrepancies resolved by a third individual). Fifty-seven percent of the papers focused on racialized/ethnic groups or other macrosocial/structural factors (e.g., segregation), 16% focused on individual-level inequalities (e.g. income), 14% focused on the built environment (e.g., walking destinations), 10% focused on social context (e.g., neighborhood socioeconomic status), 34% focused on stressors (e.g., discrimination, air pollution), and 4% focused on social support/integration (e.g., social participation). Forty-seven (11%) of the papers combined MESA with other cohorts for cross-cohort comparisons and replication/validation (e.g., validating algorithms).

CONCLUSIONS

Overall, MESA has made significant contributions to the field and the published literature, with 20% of its published papers focused on SSDOH. Future SSDOH studies using MESA would benefit by using recently added instruments/data (e.g., early life educational quality), linking SSDOH to biomarkers to determine underlying causal mechanisms linking SSDOH to CVD and aging outcomes, and by focusing on intersectionality, understudied SSDOH (i.e., social support, social context), and understudied outcomes in relation to SSDOH (i.e., sleep, respiratory health, cognition/dementia).

Comparison and evaluation of the 2009 and 2021 chronic kidney disease-epidemiological collaboration equations among Jordanian patients with type 2 diabetes mellitus

AIMS

This study compared the 2009 versus 2021 chronic kidney disease (CKD) Epidemiological Collaboration (CKD-EPI) equations to calculate estimated glomerular filtration rate (eGFR) among Jordanian patients with T2DM to assess their agreement and impact on CKD staging.

METHODS

This cross-sectional study included 2382 adult Jordanian patients with T2DM. The 2009 and 2021 CKD-EPI equations were used to calculate eGFR. Patients were reclassified according to kidney disease-Improving Global Outcomes (KDIGO) categories. Agreement between the equations was assessed using Bland-Altman plots and Lin's concordance correlation.

RESULTS

The 2021 equation significantly increased eGFR by a median of 2.1 mL/min/1.73 m2 (interquartile range: 0.6-3.6 mL/min/1.73 m2). However, there was significant agreement between equations (Kappa: 0.99; 95% confidence interval: 0.95-1.00), independent of age, sex, and the presence of hypertension. In total, 202 patients (8.5%) were reclassified to higher KDIGO categories using the 2021 equation, with category G3 being most affected. The overall prevalence of patients in the high to highest risk categories decreased (28.0% vs. 26.5%).

CONCLUSIONS

Although there was significant agreement with the 2009 equation, the 2021 equation increased eGFR and resulted in the reclassification of a subset of subjects according to KDIGO criteria. The uncertain impact of reducing high-risk category patients raises concerns about potential delays in referral and intervention, while holding the potential to enhance high-risk patient categorization, thus alleviating healthcare burden.

Comparison of cardiovascular event predictability between the 2009 and 2021 Chronic Kidney Disease Epidemiology Collaboration equations in a Korean chronic kidney disease cohort: the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease

BACKGROUND

The 2009 Chronic Kidney Disease Epidemiology Collaboration creatinine-based estimated glomerular filtration rate (eGFRcr) equation contains a race component that is not based on biology and may cause a bias in results. Therefore, the 2021 eGFRcr and creatinine-cystatin C-based eGFR (eGFRcr-cysC) equations were developed with no consideration of race. This study compared the cardiovascular event (CVE) and all-cause mortality and CVE combined predictability among the three eGFR equations in Korean chronic kidney disease (CKD) patients.

METHODS

This study included 2,207 patients from the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease. Receiver operating characteristic (ROC) and net reclassification improvement (NRI) index were used to compare the predictability of the study outcomes according to the 2009 eGFRcr, 2021 eGFRcr, and 2021 eGFRcr-cysC equations.

RESULTS

The overall prevalence of CVE and all-cause mortality were 9% and 7%, respectively. There was no difference in area under the curve of ROC for CVE and mortality and CVE combined among all three equations. Compared to the 2009 eGFRcr, both the 2021 eGFRcr (NRI, 0.013; 95% confidence interval [CI], - 0.002 to 0.028) and the eGFRcr-cysC (NRI, -0.001; 95% CI, -0.031 to 0.029) equations did not show improved CVE predictability. Similar findings were observed for mortality and CVE combined predictability with both the 2021 eGFRcr (NRI, -0.019; 95% CI, -0.039-0.000) and the eGFRcr-cysC (NRI, -0.002; 95% CI, -0.023 to 0.018).

CONCLUSION

The 2009 eGFRcr equation was not inferior to either the 2021 eGFRcr or eGFRcr-cysC equation in predicting CVE and the composite of mortality and CVE in Korean CKD patients.

Individualization of the Dosage Regimen of Erythropoietin is Crucial in End-stage Renal Disease Patients

The objective of this study was to understand the utilization pattern of erythropoietin in end-stage renal disease patients, along with the effect of body weight and sex on the patients' responses. In this retrospective single-center study, 120 patients were included who were on a once weekly (n = 79), twice weekly (n = 37), or thrice weekly (n = 4) regimen. The doses of erythropoiesis-stimulating agents (ESA) were collected, and the erythropoietin resistance index (ERI) was determined. The Kruskal-Wallis test was used to evaluate the dose schedules, and the once-weekly regimen produced a greater response (P = 0.001). The asymptotic significance of Pearson's Chi-square-test equating the mean ERI and body mass index (BMI) was 0.034. No statistically significant correlation was estimated between sex and mean ERI (P = 0.201). Our study demonstrated that the once-weekly regimen dominated over the others in terms of efficacy, and individuals with a higher BMI were found to respond better to the ESA therapy.

Impact of Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) GFR Estimating Equations on CKD Prevalence and Classification Among Asians

Background

In 2021, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) validated a new equation for estimated glomerular filtration rate (eGFR). However, this new equation is not ethnic-specific, and prevalence of CKD in Asians is known to differ from other ethnicities. This study evaluates the impact of the 2009 and 2021 creatinine-based eGFR equations on the prevalence of CKD in multiple Asian cohorts.

Methods

Eight population-based studies from China, India, Russia (Asian), Singapore and South Korea provided individual-level data (n = 67,233). GFR was estimated using both the 2009 CKD-EPI equation developed using creatinine, age, sex, and race (eGFRcr [2009, ASR]) and the 2021 CKD-EPI equation developed without race (eGFRcr [2021, AS]). CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2 (G3-G5). Prevalence of eGFR categories was compared within each study and within subgroups of age, sex, body mass index (BMI), diabetes, and hypertension status. The extent of reclassification was examined using net reclassification improvement (NRI).

Findings

Of 67,233 adults, CKD prevalence was 8.6% (n = 5800/67,233) using eGFRcr (2009, ASR) and 6.4% (n = 4307/67,233) using eGFRcr (2021, AS). With the latter, CKD prevalence was reduced across all eight studies, ranging from −7.0% (95% CI −8.5% to −5.4%) to −0.4% (−1.3% to 0.5%), and across all subgroups except those in the BMI < 18.5% subgroup. Net reclassification index (NRI) was significant at −2.33% (p < 0.001). No individuals were reclassified as a higher (more severe) eGFR category, while 1.7%−4.2% of individuals with CKD were reclassified as one eGFR category lower when eGFRcr (2021, AS) rather than eGFRcr (2009, ASR) was used.

Interpretation

eGFRcr (2021, AS) consistently provided reduced CKD prevalence and higher estimation of GFR among Asian cohorts than eGFRcr (2009, ASR). Based on current risk-stratified approaches to CKD management, more patients reclassified to lower-risk GFR categories could help reduce inappropriate care and its associated adverse effects among Asian renal patients. Comparison of both equations to predict progression to renal failure or adverse outcomes using prospective studies are warranted.

Funding

National Medical Research Council, Singapore.

The KIDNEYCODE Program: Diagnostic Yield and Clinical Features of Individuals with CKD

Background

Despite increasing recognition that CKD may have underlyi ng genetic causes, genetic testing remains limited. This study evaluated the diagnostic yield and phenotypic spectrum of CKD in individuals tested through the KIDNEYCODE sponsored genetic testing program.

Methods

Unrelated individuals who received panel testing (17 genes) through the KIDNEYCODE sponsored genetic testing program were included. Individuals had to meet at least one of the following eligibility criteria: eGFR ≤90 ml/min per 1.73m2 and hematuria or a family history of kidney disease; or suspected/biopsy-confirmed Alport syndrome or FSGS in tested individuals or relatives.

Results

Among 859 individuals, 234 (27%) had molecular diagnoses in genes associated with Alport syndrome (n=209), FSGS (n=12), polycystic kidney disease (n=6), and other disorders (n=8). Among those with positive findings in a COL4A gene, the majority were in COL4A5 (n=157, 72 hemizygous male and 85 heterozygous female individuals). A positive family history of CKD, regardless of whether clinical features were reported, was more predictive of a positive finding than was the presence of clinical features alone. For the 248 individuals who had kidney biopsies, a molecular diagnosis was returned for 49 individuals (20%). Most (n=41) individuals had a molecular diagnosis in a COL4A gene, 25 of whom had a previous Alport syndrome clinical diagnosis, and the remaining 16 had previous clinical diagnoses including FSGS (n=2), thin basement membrane disease (n=9), and hematuria (n=1). In total, 491 individuals had a previous clinical diagnosis, 148 (30%) of whom received a molecular diagnosis, the majority (89%, n=131) of which were concordant.

Conclusions

Although skewed to identify individuals with Alport syndrome, these findings support the need to improve access to genetic testing for patients with CKD-particularly in the context of family history of kidney disease, hematuria, and hearing loss.

Diagnostic Accuracy of Serum Cystatin C for Early Recognition of Nephropathy in Type 2 Diabetes Mellitus

Objectives

Diabetic nephropathy is one of the major complications that develop over time in type 2 diabetes mellitus (T2DM). This prospective study was conducted to assess the diagnostic accuracy of serum cystatin C in detecting diabetic nephropathy at earlier stages.

Materials and Methods

This study was undertaken on 50 cases of T2DM and 50 healthy subjects as controls. Demographic and anthropometric data and blood and urine samples were collected. The concentration of serum cystatin C (index test) and traditional markers of diabetic nephropathy, serum creatinine, and urinary microalbumin (the reference standard) were estimated. Similarly, blood glucose, glycated haemoglobin (HbA1c), triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, and urinary creatine were measured.

Results

The mean ± SD serum cystatin C was significantly higher in T2DM as compared to control (1.07 ± 0.38 and 0.86 ± 0.12 mg/dl, respectively, p < 0.001). The mean ± SD bodyweight, BMI, W : H ratio, pulse, SBP, and DBP were 66.4 ± 12.6 kg, 26.2 ± 5.6 kg/m², 1.03 ± 0.09, 78 ± 7, 125 ± 16 mm of Hg, and 77 ± 9 mm of Hg, respectively, in cases. A significant difference in HDL cholesterol (p=0.018) and serum cystatin C (p < 0.001) was observed among different grades of nephropathy. Cystatin C had a significant positive correlation with age (r = 0.323, p=0.022), duration of T2DM (r = 0.326, p=0.021), and UACR (r = 0.528, p < 0.001) and a significant negative correlation with eGFR CKD-EPI cystatin C (r = −0.925, p < 0.001). The area under ROC curve for serum cystatin C (0.611, 95% CI: 0.450–0.772) was greater than for serum creatinine (0.429, 95% CI: 0.265–0.593) though nonsignificant.

Conclusion

Serum cystatin C concentration increases with the progression of nephropathy and duration of diabetes in Nepalese T2DM patients suggesting cystatin C as a potential marker of renal impairment in T2DM patients.

Fertility and reproductive care in chronic kidney disease

In both women and men, chronic kidney disease (CKD) is associated with decreased fertility. Though a multitude of factors contribute to the reduction in fertility in this population, progressively impaired function of the hypothalamic-pituitary-gonadal axis appears to play a key role in the pathophysiology. There is limited research on strategies to manage infertility in the CKD population, but intensive hemodialysis, kidney transplantation, medication management and assisted reproductive technologies (ART) have all been proposed. Though fertility and reproductive care are reported as important elements of care by CKD patients themselves, few nephrology clinicians routinely address fertility and reproductive care in clinical interactions. Globally, the average age of parenthood is increasing, with concurrent growth and expansion in the use of ART. Coupled with an increasing prevalence of CKD in women and men of reproductive age, the importance of understanding fertility and reproductive technologies in this population is highlighted. This review endeavors to explore the female and male factors that affect fertility in the CKD population, as well as the evidence supporting strategies for reproductive care.

Performance of glomerular filtration rate estimation equations in Congolese healthy adults: The inopportunity of the ethnic correction

Context and objective

In the estimation of glomerular filtration rate (GFR), ethnicity is an important determinant. However, all existing equations have been built solely from Caucasian and Afro-American populations and they are potentially inaccurate for estimating GFR in African populations. We therefore evaluated the performance of different estimated GFR (eGFR) equations in predicting measured GFR (mGFR).

Methods

In a cross-sectional study, 93 healthy adults were randomly selected in the general population of Kinshasa, Democratic Republic of the Congo, between June 2015 and April 2016. We compared mGFR by plasma clearance of iohexol with eGFR obtained with the Modified Diet in Renal Disease (MDRD) equation with and without ethnic factor, the Chronic Kidney Disease Epidemiology (CKD-EPI) serum creatinine (SCr)-based equation, with and without ethnic factor, the cystatin C-based CKD-EPI equation (CKD-EPI SCys) and with the combined equation (CKD-EPI SCrCys) with and without ethnic factor. The performance of the equations was studied by calculating bias, precision and accuracy within 30% (P30) of mGFR.

Results

There were 48 women and 45 men. Their mean age was 45.0±15.7 years and the average body surface area was 1.68±0.16m². Mean mGFR was 92.0±17.2 mL/min/1.73m² (range of 57 to 141 mL/min/1.73m²). Mean eGFRs with the different equations were 105.5±30.1 and 87.2±24.8 mL/min/1.73m² for MDRD with and without ethnic factor, respectively; 108.8±24.1 and 94.3x20.9 mL/min/1.73m² for CKD-EPI SCr with and without ethnic factor, respectively, 93.5±18.6 mL/min/1.73m² for CKD-EPI SCys; 93.5±18.0 and 101±19.6 mL/min/ 1.73m² for CKD-EPI SCrCys with and without ethnic factor, respectively. All equations slightly overestimated mGFR except MDRD without ethnic factor which underestimated by -3.8±23.0 mL/min /1.73m². Both CKD-EPI SCr and MDRD with ethnic factors highly overestimated mGFR with a bias of 17.9±19.2 and 14.5±27.1 mL/min/1.73m², respectively. There was a trend for better P30 for MDRD and CKD-EPI SCr without than with the ethnic factor [86.0% versus 79.6% for MDRD (p = 0.21) and 81.7% versus 73.1% for the CKD-EPI SCr equations (p = 0.057)]. CKD-EPI SCrCys and CKD-EPI SCys were more effective than creatinine-based equations.

Conclusion

In the Congolese healthy population, MDRD and CKD-EPI equations without ethnic factors had better performance than the same equations with ethnic factor. The equations using Cys C (alone or combined with SCr) performed better than the creatinine-based equations.

Gaps in translation from trials to practice: Non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention in atrial fibrillation

Worldwide there is a tremendous need for affordable anticoagulants that do not require monitoring. The advent of the non-warfarin oral anticoagulant drugs represents a major advance for stroke prevention in atrial fibrillation (AF). The objectives of this review are to 1) identify gaps in our current knowledge regarding use of these single target anticoagulant drugs; 2) outline the potential implications of these gaps for clinical practice, and thereby, 3) highlight areas of research to further optimise their use for stroke prevention in AF.

Global kidney health 2017 and beyond: a roadmap for closing gaps in care, research, and policy

The global nephrology community recognises the need for a cohesive plan to address the problem of chronic kidney disease (CKD). In July, 2016, the International Society of Nephrology hosted a CKD summit of more than 85 people with diverse expertise and professional backgrounds from around the globe. The purpose was to identify and prioritise key activities for the next 5-10 years in the domains of clinical care, research, and advocacy and to create an action plan and performance framework based on ten themes: strengthen CKD surveillance; tackle major risk factors for CKD; reduce acute kidney injury-a special risk factor for CKD; enhance understanding of the genetic causes of CKD; establish better diagnostic methods in CKD; improve understanding of the natural course of CKD; assess and implement established treatment options in patients with CKD; improve management of symptoms and complications of CKD; develop novel therapeutic interventions to slow CKD progression and reduce CKD complications; and increase the quantity and quality of clinical trials in CKD. Each group produced a prioritised list of goals, activities, and a set of key deliverable objectives for each of the themes. The intended users of this action plan are clinicians, patients, scientists, industry partners, governments, and advocacy organisations. Implementation of this integrated comprehensive plan will benefit people who are at risk for or affected by CKD worldwide.

Perceived Discrimination and Longitudinal Change in Kidney Function Among Urban Adults

OBJECTIVE

Perceived discrimination has been associated with psychosocial distress and adverse health outcomes. We examined associations of perceived discrimination measures with changes in kidney function in a prospective cohort study, the Healthy Aging in Neighborhoods of Diversity across the Life Span.

METHODS

Our study included 1620 participants with preserved baseline kidney function (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m) (662 whites and 958 African Americans, aged 30-64 years). Self-reported perceived racial discrimination and perceived gender discrimination (PGD) and a general measure of experience of discrimination (EOD) ("medium versus low," "high versus low") were examined in relation to baseline, follow-up, and annual rate of change in eGFR using multiple mixed-effects regression (γbase, γrate) and ordinary least square models (γfollow).

RESULTS

Perceived gender discrimination "high versus low PGD" was associated with a lower baseline eGFR in all models (γbase = -3.51 (1.34), p = .009 for total sample). Among white women, high EOD was associated with lower baseline eGFR, an effect that was strengthened in the full model (γbase = -5.86 [2.52], p = .020). Overall, "high versus low" PGD was associated with lower follow-up eGFR (γfollow = -3.03 [1.45], p = .036). Among African American women, both perceived racial discrimination and PGD were linked to lower follow-up kidney function, an effect that was attenuated with covariate adjustment, indicating mediation through health-related, psychosocial, and lifestyle factors. In contrast, EOD was not linked to follow-up eGFR in any of the sex by race groups.

CONCLUSIONS

Perceived racial and gender discrimination are associated with lower kidney function assessed by glomerular filtration rate and the strength of associations differ by sex and race groups. Perceived discrimination deserves further investigation as a psychosocial risk factors for kidney disease.

Anthracycline-Associated T1 Mapping Characteristics Are Elevated Independent of the Presence of Cardiovascular Comorbidities in Cancer Survivors

BACKGROUND

Cardiovascular magnetic resonance T1 mapping characteristics are elevated in adult cancer survivors; however, it remains unknown whether these elevations are related to age or presence of coincident cardiovascular comorbidities.

METHODS AND RESULTS

We performed blinded cardiovascular magnetic resonance analyses of left ventricular T1 and extracellular volume (ECV) fraction in 327 individuals (65% women, aged 64±12 years). Thirty-seven individuals had breast cancer or a hematologic malignancy but had not yet initiated their treatment, and 54 cancer survivors who received either anthracycline-based (n=37) or nonanthracycline-based (n=17) chemotherapy 2.8±1.3 years earlier were compared with 236 cancer-free participants. Multivariable analyses were performed to determine the association between T1/ECV measures and variables associated with myocardial fibrosis. Age-adjusted native T1 was elevated pre- (1058±7 ms) and post- (1040±7 ms) receipt of anthracycline chemotherapy versus comparators (965±3 ms; P<0.0001 for both). Age-adjusted ECV, a marker of myocardial fibrosis, was elevated in anthracycline-treated cancer participants (30.4±0.7%) compared with either pretreatment cancer (27.8±0.7%; P<0.01) or cancer-free comparators (26.9±0.2%; P<0.0001). T1 and ECV of nonanthracycline survivors were no different than pretreatment survivors (P=0.17 and P=0.16, respectively). Native T1 and ECV remained elevated in cancer survivors after accounting for demographics (including age), myocardial fibrosis risk factors, and left ventricular ejection fraction or myocardial mass index (P<0.0001 for all).

CONCLUSIONS

Three years after anthracycline-based chemotherapy, elevations in myocardial T1 and ECV occur independent of underlying cancer or cardiovascular comorbidities, suggesting that imaging biomarkers of interstitial fibrosis in cancer survivors are related to prior receipt of a potentially cardiotoxic cancer treatment regimen.

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.

Influence of common genetic variants on childhood kidney outcomes

BACKGROUND

Kidney measures in early life are associated with kidney disease in later life. We hypothesized that these associations are partly explained by common genetic variants that lead to both smaller kidneys with lower kidney function in early childhood and kidney disease in adulthood.

METHODS

We examined in a population-based prospective cohort study among 4,119 children the associations of a weighted genetic risk score combining 20 previously identified common genetic variants related to adult eGFRcreat with kidney outcomes in children aged 6.0 years (95% range 5.7-7.8). Childhood kidney outcomes included combined kidney volume, glomerular filtration rate (eGFR) based on creatinine levels, and microalbuminuria based on albumin and creatinine urine levels.

RESULTS

We observed that the genetic risk score based on variants related to impaired kidney function in adults was associated with a smaller combined kidney volume (P value 3.0 × 10(-3)) and with a lower eGFR (P value 4.0 × 10(-4)) in children. The genetic risk score was not associated with microalbuminuria.

CONCLUSION

Common genetic variants related to impaired kidney function in adults already lead to subclinical changes in childhood kidney outcomes. The well-known associations of kidney measures in early life with kidney disease in later life may at least be partly explained by common genetic variants.

Markers of kidney disease and risk of subclinical and clinical heart failure in African Americans: the Jackson Heart Study

BACKGROUND

African Americans and patients with chronic kidney disease (CKD) are at high risk for clinical heart failure (HF). In this study, we aimed to determine the association of markers of kidney disease with subclinical HF (by echocardiogram) and risk of clinical HF among a large, well-characterized community-based cohort of African American patients. We also examined whether the association of markers of kidney disease with HF was attenuated with adjustment for echocardiographic measures.

METHODS

We studied participants in the Jackson Heart Study, a large community-based cohort of African Americans. Estimated glomerular filtration rate (eGFR) and urine albumin:creatinine ratio (ACR) were measured at baseline. We tested the association of eGFR and urine ACR with left ventricular mass (LVM), left ventricular ejection fraction (LVEF) and physician-adjudicated incident HF.

RESULTS

Among the 3332 participants in the study, 166 (5%) had eGFR <60 mL/min/1.73 m² and 405 (12%) had urine ACR ≥30 mg/g. In models adjusted for demographics, comorbidity and the alternative measure of kidney disease, lower eGFR and higher urine ACR were associated with higher LVM {β-coefficient 1.54 [95% confidence interval (CI) 0.78-2.31] per 10 mL/min/1.73 m² decrease in eGFR and 2.87 (95% CI 1.85-3.88) per doubling of urine ACR}. There was no association of eGFR and urine ACR with LVEF [β-coefficient -0.12 (95% CI -0.28-0.04) and -0.11 (95% CI -0.35-0.12), respectively]. There was no association of eGFR with the risk of incident HF [HR 1.02 (95% CI 0.91-1.14) per 10 mL/min/1.73 m² decrease], while there was a significant association of urine ACR [HR 2.22 (95% CI 1.29-3.84) per doubling of urine ACR]. This association was only modestly attenuated with adjustment for LVM [HR 1.95 (95% CI 1.09-3.49)].

CONCLUSIONS

Among a community-based cohort of African Americans, lower eGFR and higher ACR were associated with higher LVM. Furthermore, higher urine ACR was associated with incident HF, which was not entirely explained by the presence of left ventricular disease.

A Systems Biology Overview on Human Diabetic Nephropathy: From Genetic Susceptibility to Post-Transcriptional and Post-Translational Modifications

Diabetic nephropathy (DN), a microvascular complication occurring in approximately 20-40% of patients with type 2 diabetes mellitus (T2DM), is characterized by the progressive impairment of glomerular filtration and the development of Kimmelstiel-Wilson lesions leading to end-stage renal failure (ESRD). The causes and molecular mechanisms mediating the onset of T2DM chronic complications are yet sketchy and it is not clear why disease progression occurs only in some patients. We performed a systematic analysis of the most relevant studies investigating genetic susceptibility and specific transcriptomic, epigenetic, proteomic, and metabolomic patterns in order to summarize the most significant traits associated with the disease onset and progression. The picture that emerges is complex and fascinating as it includes the regulation/dysregulation of numerous biological processes, converging toward the activation of inflammatory processes, oxidative stress, remodeling of cellular function and morphology, and disturbance of metabolic pathways. The growing interest in the characterization of protein post-translational modifications and the importance of handling large datasets using a systems biology approach are also discussed.

Potential Impact of Prescribing Metformin According to eGFR Rather Than Serum Creatinine

OBJECTIVE

Many societies recommend using estimated glomerular filtration rate (eGFR) rather than serum creatinine (sCr) to determine metformin eligibility. We examined the potential impact of these recommendations on metformin eligibility among U.S. adults.

RESEARCH DESIGN AND METHODS

Metformin eligibility was assessed among 3,902 adults with diabetes who participated in the 1999-2010 National Health and Nutrition Examination Surveys and reported routine access to health care, using conventional sCr thresholds (eligible if <1.4 mg/dL for women and <1.5 mg/dL for men) and eGFR categories: likely safe, ≥45 mL/min/1.73 m(2); contraindicated, <30 mL/min/1.73 m(2); and indeterminate, 30-44 mL/min/1.73 m(2)). Different eGFR equations were used: four-variable MDRD, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine (CKD-EPIcr), and CKD-EPI cystatin C, as well as Cockcroft-Gault (CG) to estimate creatinine clearance (CrCl). Diabetes was defined by self-report or A1C ≥6.5% (48 mmol/mol). We used logistic regression to identify populations for whom metformin was likely safe adjusted for age, race/ethnicity, and sex. Results were weighted to the U.S. adult population.

RESULTS

Among adults with sCr above conventional cutoffs, MDRD eGFR ≥45 mL/min/1.73 m(2) was most common among men (adjusted odds ratio [aOR] 33.3 [95% CI 7.4-151.5] vs. women) and non-Hispanic Blacks (aOR vs. whites 14.8 [4.27-51.7]). No individuals with sCr below conventional cutoffs had an MDRD eGFR <30 mL/min/1.73 m(2). All estimating equations expanded the population of individuals for whom metformin is likely safe, ranging from 86,900 (CKD-EPIcr) to 834,800 (CG). All equations identified larger populations with eGFR 30-44 mL/min/1.73 m(2), for whom metformin safety is indeterminate, ranging from 784,700 (CKD-EPIcr) to 1,636,000 (CG).

CONCLUSIONS

The use of eGFR or CrCl to determine metformin eligibility instead of sCr can expand the adult population with diabetes for whom metformin is likely safe, particularly among non-Hispanic blacks and men.

Impact of protein energy wasting status on survival among Afro-Caribbean hemodialysis patients: a 3-year prospective study

Background

We assessed the prognostic value of protein-energy wasting (PEW) on mortality in Afro-Caribbean MHD patients and analysed how diabetes, cardiovascular disease (CVD) and inflammation modified the predictive power of a severe wasting state.

Method

A 3-year prospective study was conducted in 216 patients from December 2011. We used four criteria from the nomenclature for PEW proposed by the International Society of Renal Nutrition and Metabolism in 2008: serum albumin 38 g/L, body mass index (BMI) ≤23 kg/m², serum creatinine ≤818 µmol/L and protein intake assessed by nPCR ≤0.8 g/kg/day. PEW status was categorized according the number of criteria. Cox regression analyses were used.

Results

Forty deaths (18.5 %) occurred, 97.5 % with a CV cause. Deaths were distributed as follows: 7.4 % in normal nutritional status, 13.2 % in slight wasting (1 PEW criterion), 28 % in moderate wasting (2 criteria) and 50 % in severe wasting (3–4 criteria). Among the PEW markers, low serum albumin (HR 3.18; P = 0.001) and low BMI (HR 1.97; P = 0.034) were the most significant predictors of death. Among the PEW status categories, moderate wasting (HR 3.43; P = 0.021) and severe wasting (HR 6.59; P = 0.001) were significant predictors of death. Diabetes, CVD, and inflammation were all additives in predicting death in association with severe wasting with a strongest HR (7.76; P < 0.001) for diabetic patients.

Conclusions

The nomenclature for PEW predicts mortality in our Afro-Caribbean MHD patients and help to identify patients at risk of severe wasting to provide adequate nutritional support.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-015-1257-3) contains supplementary material, which is available to authorized users.

Aging and low-grade inflammation reduce renal function in middle-aged and older adults in Japan and the USA

The objective of this study was to investigate the effects of low-grade inflammation on age-related changes in glomerular filtration rate (GFR) in middle-aged and older white Americans, African-Americans, and Japanese adults. Serum creatinine, C-reactive protein (CRP), and interleukin-6 (IL-6) levels were determined for 1570 adult participants in two surveys of aging in the USA and Japan (N = 1188 and 382, respectively). Kidney function declined with age in both countries and was associated with IL-6 and CRP. IL-6 and CRP also influenced the extent of the arithmetic bias when calculating the GFR using the chronic kidney disease epidemiology (CKD-EPI) formula with just serum creatinine. Younger African-Americans initially had the highest GFR but showed a steep age-related decrement that was associated with elevated inflammation. Japanese adults had the lowest average GFR but evinced a large effect of increased inflammatory activity when over 70 years of age. Importantly, our results also indicate that low-grade inflammation is important to consider when evaluating kidney function solely from serum creatinine.

Kidney size and function in a multi-ethnic population-based cohort of school-age children

BACKGROUND

Subclinical impaired kidney growth and function in childhood may lead to kidney diseases and high blood pressure in adulthood. We assessed the cross-sectional associations of childhood characteristics with kidney size and function in a multi-ethnic cohort.

METHODS

This study was embedded in a population-based cohort study of 6,397 children with a median age of 6.0 years.Kidney volume, creatinine and cystatin C blood levels, microalbuminuria and blood pressure were measured, and glomerular filtration rate (GFR) was estimated.

RESULTS

Childhood anthropometrics were positively associated with kidney volume, creatinine level and blood pressure (all p < 0.05). We observed ethnic differences in all kidney size and function measures (all p < 0.05). Children with smaller kidneys had higher creatinine and cystatin C blood levels, leading to a lower estimated GFR [difference 5.68 ml/min/1.73 m2 (95% confidence interval 5.14-6.12) per 1 standard deviation increase in kidney volume]. Larger kidney volume was associated with an increased risk of microalbuminuria.

CONCLUSIONS

Childhood kidney volume and function are influenced by body mass index and ethnicity. Kidney volume is related with kidney function but not with blood pressure. These results may help to identify individuals at risk for kidney disease in an early stage.

Association between shiftwork and glomerular filtration rate in police officers

OBJECTIVE

To investigate associations between shiftwork and glomerular filtration rate among white/Hispanic (n = 273) and African American (n = 81) police officers.

METHODS

Analysis of variance/analysis of variance was utilized to compare mean values of estimated glomerular filtration rate (eGFR) across shiftwork categories.

RESULTS

Shiftwork was significantly associated with eGFR among white/Hispanic officers only: day (88.6 ± 2.8), afternoon (90.6 ± 2.9), and night shift (83.1 ± 3.1 mL/min/1.73 m); afternoon versus night, P = 0.007. Percentage of hours worked on the night shift was inversely associated with mean levels of eGFR, trend P = 0.001. Body mass index modified the association between shiftwork and eGFR (interaction P = 0.038). Among officers with body mass index 25 kg/m or higher, those who worked the night shift had the lowest mean eGFR (afternoon vs night, P = 0.012; day vs night, P = 0.029).

CONCLUSIONS

Night-shift work was associated with decreased kidney function among white/Hispanic officers. Longitudinal studies are warranted among all races.

Racial/ethnic differences in the prevalence of proteinuric and nonproteinuric diabetic kidney disease

OBJECTIVE

To examine racial/ethnic differences in the prevalence of diabetic kidney disease (DKD), with and without proteinuria, in an outpatient health care organization.

RESEARCH DESIGN AND METHODS

We examined electronic health records for 15,683 persons of non-Hispanic white (NHW), Asian (Asian Indian, Chinese, and Filipino), Hispanic, and non-Hispanic black (NHB) race/ethnicity with type 2 diabetes and no prior history of kidney disease from 2008 to 2010. We directly standardized age- and sex-adjusted prevalence rates of proteinuric DKD (proteinuria with or without low estimated glomerular filtration rate [eGFR]) or nonproteinuric DKD (low eGFR alone). We calculated sex-specific odds ratios of DKD in racial/ethnic minorities (relative to NHWs) after adjustment for traditional DKD risk factors.

RESULTS

Racial/ethnic minorities had higher rates of proteinuric DKD than NHWs (24.8-37.9 vs. 24.8%) and lower rates of nonproteinuric DKD (6.3-9.8 vs. 11.7%). On adjusted analyses, Chinese (odds ratio 1.39 for women and 1.56 for men), Filipinos (1.57 for women and 1.85 for men), Hispanics (1.46 for women and 1.34 for men), and NHBs (1.50 for women) exhibited significantly (P < 0.01) higher odds of proteinuric DKD than NHWs. Conversely, Chinese, Hispanic, and NHB women and Hispanic men had significantly lower odds of nonproteinuric DKD than NHWs.

CONCLUSIONS

We found novel racial/ethnic differences in DKD among patients with type 2 diabetes. Racial/ethnic minorities were more likely to have proteinuric DKD and less likely to have nonproteinuric DKD. Future research should examine diverse DKD-related outcomes by race/ethnicity to inform targeted prevention and treatment efforts and to explore the etiology of these differences.

Blood pressure and chronic kidney disease progression in a multi-racial cohort: the Multi-Ethnic Study of Atherosclerosis

The relationship between blood pressure (BP) and kidney function among individuals with chronic kidney disease (CKD) remains controversial. This study evaluated the association between BP and estimated glomerular filtration rate (eGFR) decline among adults with nondiabetic stage 3 CKD. The Multi-Ethnic Study of Atherosclerosis participants with an eGFR 30-59  ml min(-1) per 1.73 m2 at baseline without diabetes were included. Participants were followed over a 5-year period. Kidney function change was determined by annualizing the change in eGFR using cystatin C, creatinine and a combined equation. Risk factors for progression of CKD (defined as a decrease in annualized eGFR>2.5 ml min(-1) per 1.73 m2) were identified using univariate analyses and sequential logistic regression models. There were 220 participants with stage 3 CKD at baseline using cystatin C, 483 participants using creatinine and 381 participants using the combined equation. The median (interquartile range) age of the sample was 74 (68-79) years. The incidence of progression of CKD was 16.8% using cystatin C and 8.9% using creatinine (P=0.002). Systolic BP>140 mm Hg or diastolic BP>90 mm Hg was significantly associated with progression using a cystatin C-based (odds ratio (OR), 2.49; 95% confidence interval (CI), 1.12-5.52) or the combined equation (OR, 2.07; 95% CI, 1.16-3.69), but not when using creatinine after adjustment for covariates. In conclusion, with the inclusion of cystatin C in the eGFR assessment hypertension was an important predictor of CKD progression in a multi-ethnic cohort with stage 3 CKD.

Comparison of 12-hour creatinine clearance and estimated glomerular filtration rate in renal transplant recipients

Glomerular filtration rate (GFR) is an essential clinical assessment of renal function post-renal transplantation. Creatinine clearance (CrCl) measured over 12 h and estimated GFR (e-GFR) (calculated by the Modification of diet in renal disease equation) were compared in 28 stable renal transplant recipients (RTRs). This single center study included 14 African American (AA) and 14 Caucasian (CC) recipients. The 12-h creatinine clearance (CrCl-12 h) was determined by monitored urine collection and by e-GFR on two occasions (two phases) separated by at least 2 weeks. Statistics included mixed model analysis of CrCl-12 h and e-GFR relative to race, phase, and difference between parameters. In the first phase, the e-GFR was higher in AA males (58.4 ± 14.8 mL/min) than the CC males (46.2 ± 10.2 mL/min) (p = 0.032), whereas the CrCl-12 h of AA males (70.8 ± 8.7 mL/min) and CC males (63.3 ± 21.7 mL/min) was not different (p = 0.740). During the second phase, the e-GFR in AA and CC RTRs was 55.4 ± 10.1 mL/min and 47.6 ± 10.7 mL/min (p = 0.117), respectively, whereas CrCl-12 h in AAs was 64.71 ± 17.9 mL/min and in CCs was 62.0 ± 14.9 mL/min (p = 1.000). The CrCl-12 h was higher than the e-GFR (p < 0.001) irrespective of race or phase. CrCl-12 h was not different on both occasions (p = 0.289) in all the patients. CrCl-12 h was consistently greater than e-GFR. The difference between these e-GFR estimates may have an importance in the care of RTRs.

Association between chronic kidney disease detected using creatinine and cystatin C and death and cardiovascular events in elderly Mexican Americans: the Sacramento Area Latino Study on Aging

OBJECTIVES

Creatinine, the current clinical standard to detect chronic kidney disease (CKD), is biased by muscle mass, age and race. The authors sought to determine whether cystatin C, an alternative marker of kidney function less biased by these factors, can identify elderly Mexican Americans with CKD who are at high risk for death and cardiovascular disease.

DESIGN

Longitudinal, with mean follow-up of 6.8 years.

SETTING

Sacramento Area Latino Study of Aging (SALSA).

PARTICIPANTS

One thousand four hundred and thirty five Mexican Americans aged 60 to 101.

MEASUREMENTS

Estimated glomerular filtration rate (eGFR, mL/min per 1.73 m(2)) was determined according to creatinine (eGFRcreat) and cystatin C (eGFRcys), and participants were classified into four mutually exclusive categories: CKD neither (eGFRcreat ≥60 mL/min per 1.73 m(2); eGFRcys ≥60 mL/min per 1.73 m(2)), CKD creatinine only (eGFRcreat <60 mL/min per 1.73 m(2); eGFRcys ≥60 mL/min per 1.73 m(2)), CKD cystatin only (eGFRcreat ≥60 mL/min per 1.73 m(2); eGFRcys <60), and CKD both (eGFRcreat <60 mL/min per 1.73 m(2); GFRcys <60 mL/min per 1.73 m(2)). The associations between each CKD classification and all-cause death and cardiovascular (CV) death were studied using Cox regression.

RESULTS

At baseline, mean age was 71 ± 7; 481 (34%) had diabetes mellitus, and 980 (68%) had hypertension. Persons with CKD both had higher risk for all-cause (HR = 2.30, 95% confidence interval (CI) = 1.78-2.98) and CV disease (CVD) (HR = 2.75, 95% CI = 1.96-3.86) death than CKD neither after full adjustment. Persons with CKD cystatin C only were also at greater risk of all-cause (HR = 1.91, 95% CI = 1.37-2.67) and CV (HR = 2.56, 95% CI = 1.64-3.99) death than CKD neither. In contrast, persons with CKD creatinine only were not at greater risk for CV death (HR = 1.39, 95% CI = 0.71-2.72) but were at higher risk for all-cause death (HR = 1.95, 95% CI = 1.27-2.98).

CONCLUSION

Cystatin C may be a useful alternative to creatinine for detecting high risk of death and CVD in elderly Mexican Americans with CKD.

Cis-vaccenic acid and the Framingham risk score predict chronic kidney disease: the multi-ethnic study of atherosclerosis (MESA)

INTRODUCTION

Data on the associations of fatty acids with chronic kidney disease (CKD) are sparse.

MATERIALS AND METHODS

We performed a cross-sectional study of 2792 men and women from the MESA cohort of African-American, Caucasian, Chinese and Hispanic adults without known cardiovascular disease. Plasma phospholipid fatty acid proportions were associated with estimated glomerular filtration rate (eGFR) and the albumin/creatinine ratio.

RESULTS

Cis-vaccenic acid (18:1n-7), adjusted for other fatty acids using multivariate logistic regression (CI: 1.0-1.4), and step-wise logistic regression (CI: 1.02-1.42), was positively associated with reduced eGFR. The Framingham Risk Score, when adjusting for fatty acid proportions and demographic factors, was positively associated with CKD as measured by the eGFR and the albumin/creatinine ratio.

DISCUSSION AND CONCLUSIONS

Plasma phospholipid proportions of the 18 carbon monounsaturated cis-vaccenic acid {18:1n-7}) and the Framingham Risk Score are associated with kidney function. The potential role of 18:1n-7 in the development of CKD warrants further investigation.

Renal function and nonvertebral fracture risk in multiethnic women: the Women's Health Initiative (WHI)

To examine the association between renal function and fracture in multiethnic women, we studied postmenopausal women enrolled in the Women's Health Initiative. Postmenopausal White women with mild renal dysfunction were at increased risk of nonvertebral fracture; this association was at least partially explained by effects of renal dysfunction on chronic inflammation. Reduced renal function appeared to increase fracture risk among Black women, but there was little evidence to support this association among other racial/ethnic groups.

INTRODUCTION

The purpose of this study was to determine whether renal function is associated with fracture risk within racial/ethnic groups.

METHODS

A nested case-control study was conducted among 93,673 postmenopausal women; incident nonvertebral fractures were identified in 362 Black, 183 Hispanic, 110 Asian, and 45 American-Indian women. A random sample of 395 White women with incident nonvertebral fracture was chosen. One nonfracture control for each case was selected (matched on age, race/ethnicity, and blood draw date). Cystatin C levels were measured using baseline serum, and estimated glomerular filtration rate calculated (eGFR(cys-c)).

RESULTS

Each 1 SD increase in cystatin C was associated with a 1.2-fold increased risk of fracture among White women (adjusted odds ratios [OR], 1.23; 95% confidence intervals [CI], 1.04-1.46). The OR of fracture was 1.16 (95% CI, 0.85-1.58) among women with eGFR(cys-c) 60-90 mL/min/1.73 m(2) and 2.46 (95% CI, 1.16-5.21) among those with eGFR(cys-c) <60 mL/min/1.73 m(2) compared to the reference group (eGFR(cys-c) >90 mL/min/1.73 m(2)) (p trend = 0.05). The association was reduced after adjustment for cytokine TNFα soluble receptors (OR, 1.62; 95% CI, 0.59-4.46 for eGFR(cys-c) <60 mL/min/1.73 m(2)). Among Blacks, there was an association between cystatin C and fracture risk (OR per 1 SD increase, 1.15; 95% CI, 1.00-1.32); after adjustment, this association was only modestly attenuated, but no longer statistically significant. There was no evidence of significant associations among Hispanic, Asian, or American-Indian women.

CONCLUSION

Postmenopausal White women with mild renal dysfunction are at increased risk of nonvertebral fracture. Effects of renal function on chronic inflammation may mediate this association. Reduced renal function may increase fracture risk among Black women, but there was little evidence to support this association among other racial/ethnic groups.

Racial differences in the incidence of chronic kidney disease

BACKGROUND AND OBJECTIVES

The incidence of ESRD is higher in African Americans than in whites, despite reports of a similar or lower prevalence of CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study compared the incidence of CKD among young African-American and white adults over 20 years of follow-up in the community-based Coronary Artery Risk Development in Young Adults study. Participants included 4119 adults, 18-30 years of age, with an estimated GFR (eGFR) ≥60 ml/min per 1.73 m(2) at baseline. Incident CKD was defined as an eGFR <60 ml/min per 1.73 m(2) and a ≥25% decline in eGFR at study visits conducted 10, 15, and 20 years after baseline.

RESULTS

At baseline, the mean age of African Americans and whites was 24 and 26 years, respectively (P<0.001), and 56% and 53% of participants, respectively, were women (P=0.06). There were 43 incident cases of CKD during follow-up, 29 (1.4%) among African Americans and 14 (0.7%) among whites (P=0.02). The age- and sex-adjusted hazard ratio (HR) for incident CKD comparing African Americans to whites was 2.56 (95% confidence interval [95% CI], 1.35-5.05). After further adjustment for body mass index, systolic BP, fasting plasma glucose, and HDL cholesterol, the HR was 2.51 (95% CI, 1.25-5.05). After multivariable adjustment including albuminuria at year 10, the HR for CKD at year 15 or 20 was 1.12 (95% CI, 0.52-2.41).

CONCLUSIONS

In this study, the 20-year CKD incidence was higher among African Americans than whites, a difference that is explained in part by albuminuria.

Ethnic differences in the development of albuminuria: the DISTANCE study

OBJECTIVES

To determine whether ethnic differences in the incidence of albuminuria are present in patients with diabetes, and to identify social, behavioral, and provider factors that explain ethnic differences.

STUDY DESIGN

Survey follow-up design with a race-stratified baseline survey (2005-2006) in diabetic patients from a nonprofit, fully integrated healthcare system in Northern California. We followed the 10,596 respondents (30% whites, 20% blacks, 23% Hispanics, 14% Asians, and 13% Filipinos) without evidence of prevalent albuminuria at baseline.

METHODS

Incident albuminuria was defined by positive dipstick urinalysis (>1) or urine albumin to creatinine level (>30 mg/g), and confirmed with repeat testing at least 3 months later.

RESULTS

The 27,292 person-years of observation yielded 981 incident albuminuria events. Agestandardized rates of albuminuria (per 1000 person-years) ranged from 13.6 (95% confidence interval [CI] 10.5-17.0) in whites to 27.8 (CI 18.2- 38.3) in blacks. In fully adjusted Cox models, the hazard ratio for blacks (1.22, 95% CI 1.09-1.38), Asians (1.35, 95% CI 1.13-1.61), and Filipinos (1.93, 95% CI 1.61-2.32), but not Hispanics, was significantly greater than it was for whites. In some cases, point estimates changed markedly from the base model when fully adjusted for potential confounders. Moreover, adjustment for an array of potentially mediating factors explained only a small proportion of the observed ethnic disparities.

CONCLUSIONS

Despite uniform medical care coverage, Filipinos, blacks, and Asians with diabetes developed albuminuria at higher rates than white and Hispanic adults.

Albuminuria and racial disparities in the risk for ESRD

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

Special considerations on the management of Latino patients with type 2 diabetes mellitus

BACKGROUND

Latinos are the largest minority population in the United States, and are characterized by higher rates of obesity and diabetes compared to Whites. The prevalence of diagnosed diabetes in Latinos is two-fold higher than in Caucasians, and Latinos suffer from higher rates of diabetic complications and mortality. As the diabetes epidemic continues to expand and exert greater socioeconomic strain on national healthcare systems, the success of global and national healthcare initiatives for diabetes prevention and improvement of care will depend upon strategies targeted specifically toward this population. Essential to such strategies is an understanding of success factors unique to the Latino population for diabetes prevention and achievement of optimal treatment outcomes.

METHODS

A PubMed search was conducted for literature describing type 2 diabetes and its complications in Latinos. Specifically, we sought data describing epidemiology, disparities, management considerations, and success factors in this population.

RESULTS

The title search yielded more than 2000 articles, 80 of which were deemed directly relevant to this review. The inherent limitations of this subjective selection process are acknowledged.

CONCLUSIONS

A number of studies have highlighted various ethnic disparities in Latinos with diabetes including higher HbA1c levels, greater rates of obesity and metabolic syndrome, and a larger proportion of individuals with inadequate access to care. While relatively fewer studies describe success factors for redressing cultural disparities in diabetes, the current body of literature supports primary care strategies aimed at effective provider-patient relationships and culturally tailored education and lifestyle modification regimens. Further research demonstrating effective, culturally tailored practices that are suitable to the primary care setting would be of value to providers treating Latinos with diabetes.

Are the creatinine-based equations accurate to estimate glomerular filtration rate in African American populations?

Regarding the high prevalence of African American patients with ESRD, it is important to estimate the prevalence of early stages of chronic kidney disease in this specific population. Because serum creatinine concentration is dependent on muscular mass, an ethnic factor has to be applied to creatinine-based equations. Such ethnic factors have been proposed in the Modification of Diet in Renal Disease (MDRD) study equation and in the more recent Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. This review analyzes how these correction factors have been developed and how they have, or have not, been validated in external populations. It will be demonstrated that the African American factor in the MDRD study equation is accurate in African American chronic kidney disease (CKD) patients. However, it will be shown that this factor is probably too high for subjects with a GFR of ≥60 ml/min per 1.73 m(2), leading to an underestimation of the prevalence of CKD in the global African American population. It will also be confirmed that this ethnic factor is not accurate in African (non-American) subjects. Lastly, the lack of true external validation of the new CKD-EPI equations will be discussed. Additional trials seem necessary in American African and African populations to better estimate GFR and apprehend the true prevalence of CKD in this population with a high renal risk.

Cystatin C and albuminuria as risk factors for development of CKD stage 3: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

The growing burden and morbidity of chronic kidney disease (CKD) warrant effective strategies for identifying those at increased risk. We examined the association of cystatin C level and albuminuria with the development of CKD stage 3.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

5,422 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2).

PREDICTOR

Participants were categorized into 4 mutually exclusive groups: the presence or absence of microalbuminuria (albumin-creatinine ratio >17 and >25 μg/mg in men and women, respectively) in those with or without cystatin C level ≥1.0 mg/L.

OUTCOMES & MEASUREMENTS

Incident CKD stage 3 was defined as eGFR <60 mL/min/1.73 m(2) at the third or fourth visit and an annual decrease >1 mL/min/1.73 m(2). Poisson regression was used to evaluate incident rate ratios in unadjusted and adjusted analyses that include baseline eGFR.

RESULTS

Mean age was 61 years, 49% were men, 38% were white, 11% had diabetes, 13.7% had cystatin C level ≥1 mg/L, 8.4% had microalbuminuria, and 2.7% had cystatin C level ≥1 mg/L with microalbuminuria. 554 (10%) participants developed CKD stage 3 during a median follow-up of 4.7 years, and adjusted incidence rate ratios were 1.57 (95% CI, 1.19-2.07), 1.37 (95% CI, 1.13-1.66), and 2.12 (95% CI, 1.61-2.80) in those with microalbuminuria, cystatin C level ≥1 mg/L, and both, respectively, compared with those with neither.

LIMITATIONS

Relatively short follow-up and absence of measured GFR.

CONCLUSIONS

Cystatin C level and microalbuminuria are independent risk factors for incident CKD stage 3 and could be useful as screening tools to identify those at increased risk.

Cystatin C identifies chronic kidney disease patients at higher risk for complications

Although cystatin C is a stronger predictor of clinical outcomes associated with CKD than creatinine, the clinical role for cystatin C is unclear. We included 11,909 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Cardiovascular Health Study (CHS) and assessed risks for death, cardiovascular events, heart failure, and ESRD among persons categorized into mutually exclusive groups on the basis of the biomarkers that supported a diagnosis of CKD (eGFR <60 ml/min per 1.73 m(2)): creatinine only, cystatin C only, both, or neither. We used CKD-EPI equations to estimate GFR from these biomarkers. In MESA, 9% had CKD by the creatinine-based equation only, 2% had CKD by the cystatin C-based equation only, and 4% had CKD by both equations; in CHS, these percentages were 12, 4, and 13%, respectively. Compared with those without CKD, the adjusted hazard ratios (HR) for mortality in MESA were: 0.80 (95% CI 0.50 to 1.26) for CKD by creatinine only; 3.23 (95% CI 1.84 to 5.67) for CKD by cystatin C only; and 1.93 (95% CI 1.27 to 2.92) for CKD by both; in CHS, the adjusted HR were 1.09 (95% CI 0.98 to 1.21), 1.78 (95% CI 1.53 to 2.08), and 1.74 (95% CI 1.58 to 1.93), respectively. The pattern was similar for cardiovascular disease (CVD), heart failure, and kidney failure outcomes. In conclusion, among adults diagnosed with CKD using the creatinine-based CKD-EPI equation, the adverse prognosis is limited to the subset who also have CKD according to the cystatin C-based equation. Cystatin C may have a role in identifying persons with CKD who have the highest risk for complications.

Impact of moderate renal insufficiency on restenosis and adverse clinical events after sirolimus-eluting and bare metal stent implantation (from the SIRIUS trials)

Whether drug-eluting stents are effective and safe in patients with moderate renal insufficiency (RI) is unknown. We performed a pooled analysis of data from 3 blinded randomized trials of sirolimus-eluting stents (SESs) versus bare metal stents (BMSs; SIRIUS, C-SIRIUS, E-SIRIUS) that included 1,510 patients. Clinical and angiographic outcomes were stratified by the presence of RI defined by creatinine clearance calculated by the Cockcroft-Gault formula (normal ≥ 90, mild 60 to 89, moderate < 60 ml/min). Patients with baseline creatinine > 3.0 mg/dl were excluded from these trials. Baseline mild RI was present in 517 patients (34.7%, mean creatinine clearance 75.7 ml/min) and moderate RI in 228 patients (15.3%, mean creatinine clearance 47.2 ml/min). Treatment with SESs resulted in lower rates of 8-month angiographic restenosis rates in patients with RI (mild RI 6.7% vs 42.6%, p < 0.001; moderate RI 9.7% vs 39.7%, p < 0.001) and without baseline RI (7.7% vs 37.2%, p < 0.001). One-year target vessel revascularization rates were similarly decreased with SESs in patients with (mild RI 4.7% vs 24.2%, p < 0.001; moderate RI 5.5% vs 26.9%, p < 0.001) and without (8.1% vs 22.4%, p < 0.001) RI, and this benefit was maintained at 5 years. Compared to patients with normal or mild RI, patients with moderate RI had higher rates of overall mortality and cardiac death at 1 year and 5 years (death 2.6% vs 0.6%, p <0.01, and 17.5% vs 6.3%, p < 0.01, at 1 year and 5 years, respectively; cardiac death 1.3% vs 0.2%, p = 0.05, and 6.6% vs 3.4%, p = 0.04, at 1 year and 5 years, respectively). However, there was no differential effect of SESs versus BMSs on any safety end point. In conclusion, patients with moderate RI have a nearly threefold increase in 5-year mortality after percutaneous coronary intervention compared to patients without RI. The effectiveness of SESs in decreasing restenosis compared to BMSs in patients with moderate RI was preserved and rates of death and myocardial infarction were not adversely affected.

Definition of chronic kidney disease after uninephrectomy in living donors: what are the implications?

BACKGROUND

Living kidney transplant donors generally have a favorable renal functional outcome postuninephrectomy, but concern remains that a reduced glomerular filtration rate (GFR) postuninephrectomy might have harmful effects. This study examines the short-term (3 months) effect of donor nephrectomy on GFR and the occurrence of stage 3 chronic kidney disease (CKD) postuninephrectomy.

METHODS

The prevalence of stage 3 CKD (Kidney Disease Quality Outcome Initiative [GFR<60 mL/min/1.73 m]) was examined in 196 living donors by comparing preuninephrectomy and 3-month postuninephrectomy values of GFR using I-iothalamate GFR (iGFR), modification of diet in renal disease estimated GFR (eGFR), Cockcroft-Gault estimated creatinine clearance, and endogenous 24-hr creatinine clearance. The accuracy of GFR estimations for predicting iGFR was also studied.

RESULTS

The mean GFR before and after donation were iGFR, 105+/-18 and 68+/-13 mL/min/1.73 m; eGFR, 98+/-19 and 63+/-12 mL/min/1.73 m; Cockcroft-Gault estimated creatinine clearance, 125+/-33 and 85+/-22 mL/min/1.73 m, and endogenous 24-hr creatinine clearance, 133+/-38 and 86+/-24 mL/min/1.73 m, respectively. Stage 3 CKD was found postuninephrectomy in 53 donors (27%) by iGFR and in 73 donors (38%) by eGFR. The prevalence of stage 3 CKD was greater with older age. GFR estimation equations did not accurately predict iGFR, particularly postuninephrectomy.

CONCLUSIONS

Stage 3 CKD is commonly observed after living kidney donation, particularly in older donors. The long-term impact of stage 3 CKD postuninephrectomy is poorly understood and may not have the same implications as stage 3 CKD in other conditions. eGFR is a poor predictor of true GFR in kidney donors.

Association of serum cystatin C with pulse wave velocity, but not pressure wave reflection, in subjects with normal renal function or mild chronic kidney disease

BACKGROUND

This prospective cross-sectional study was conducted to clarify whether serum cystatin C levels might be associated with not only arterial stiffness, but also the pressure wave reflection, in middle-aged Japanese subjects with normal renal function or mild chronic kidney disease (CKD) (stage 1 or 2 CKD) (i.e., creatinine-based estimate of the glomerular filtration rate (eGFRcr) > or =60 ml/min/1.73 m(2) plus a result of the urine dipstick test for proteinuria of <1+).

METHODS

In 2,904 Japanese subjects (45 +/- 9 years old), the brachial-ankle pulse wave velocity (baPWV), radial augmentation index adjusted to a heart rate of 75 beats/min (rAI75), and serum cystatin C levels were measured.

RESULTS

Multivariate linear regression analysis demonstrated that the serum cystatin C levels were significantly correlated with the baPWV (standardized coefficient = 0.04, P < 0.01) even after adjustments for confounding variables, but not with the AI75 (standardized coefficient = 0.01, P = 0.71). adjusted values of the baPWV, but not those of rAI75, were higher in subjects with serum cystatin C levels in the highest tertile than in those with serum cystatin levels in the intermediate or lowest tertile.

CONCLUSION

In middle-aged Japanese subjects with normal renal function or mild CKD (stage 1 or 2 CKD) (eGFRcr >60 ml/min/1.73 m(2) plus a result of the urine dipstick test for proteinuria of <1+), the serum cystatin C levels may reflect facet of cardiovascular risk associated with arterial stiffness, but not that associated with the pressure wave reflection.

Incidence and progression of coronary calcification in chronic kidney disease: the Multi-Ethnic Study of Atherosclerosis

We studied the incidence and progression of coronary artery calcification in people with early chronic kidney disease. We used a cohort of 562 adult patients with chronic kidney disease who had an estimated glomerular filtration rate of <60 ml/min/1.73 m(2), in a community-based study of people without clinical cardiovascular disease, the Multi-Ethnic Study of Atherosclerosis. The majority had stage 3 disease. Coronary artery calcification was measured at baseline and again approximately 1.6 or 3.2 years later. The prevalence of coronary artery calcification at baseline was 66%, and its adjusted prevalence was 24% lower in African Americans as compared to Caucasians. The incidence of coronary artery calcification was 6.1% per year in women and 14.8% in men. Coronary artery calcification progressed in approximately 17% of subjects per year across all subgroups, and diabetes was associated with a 65% greater adjusted risk of progression. Male gender and diabetes were the only factors associated with adjusted coronary artery calcification incidence and progression, respectively. Our study shows that coronary artery calcification is common in people with stage 3 disease, progresses rapidly, and may contribute to cardiovascular risk.