Capacity for the management of kidney failure in the International Society of Nephrology North America and the Caribbean region: report from the 2023 ISN Global Kidney Health Atlas (ISN-GKHA).

The International Society of Nephrology Global Kidney Health Atlas charts the availability and capacity of kidney care globally. In the North America and the Caribbean region, the Atlas can identify opportunities for kidney care improvement, particularly in Caribbean countries where structures for systematic data collection are lacking. In this third iteration, respondents from 12 of 18 countries from the region reported a 2-fold higher than global median prevalence of dialysis and transplantation, and a 3-fold higher than global median prevalence of dialysis centers. The peritoneal dialysis prevalence was lower than the global median, and transplantation data were missing from 6 of the 10 Caribbean countries. Government-funded payments predominated for dialysis modalities, with greater heterogeneity in transplantation payor mix. Services for chronic kidney disease, such as monitoring of anemia and blood pressure, and diagnostic capability relying on serum creatinine and urinalyses were universally available. Notable exceptions in Caribbean countries included non-calcium-based phosphate binders and kidney biopsy services. Personnel shortages were reported across the region. Kidney failure was identified as a governmental priority more commonly than was chronic kidney disease or acute kidney injury. In this generally affluent region, patients have better access to kidney replacement therapy and chronic kidney disease-related services than in much of the world. Yet clear heterogeneity exists, especially among the Caribbean countries struggling with dialysis and personnel capacity. Important steps to improve kidney care in the region include increased emphasis on preventive care, a focus on home-based modalities and transplantation, and solutions to train and retain specialized allied health professionals.

Point-of-Care Ultrasound Training during Nephrology Fellowship: A National Survey of Fellows and Program Directors.

BACKGROUND AND OBJECTIVES: Point-of-care ultrasound (POCUS)-performed by a clinician during a patient encounter and used in patient assessment and care planning-has many potential applications in nephrology. Yet, US nephrologists have been slow to adopt POCUS, which may affect the training of nephrology fellows. This study sought to identify the current state of POCUS training and implementation in nephrology fellowships. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Concise survey instruments measuring attitudes toward POCUS, its current use, fellow competence, and POCUS curricula were disseminated to (1) 912 US nephrology fellows taking the 2021 Nephrology In-Training Examination and (2) 229 nephrology training program directors and associate program directors. Fisher exact, chi-squared, and Wilcoxon rank sum tests were used to compare the frequencies of responses and the average responses between fellows and training program directors/associate program directors when possible. RESULTS: Fellow and training program directors/associate program directors response rates were 69% and 37%, respectively. Only 38% of fellows (240 respondents) reported receiving POCUS education during their fellowship, and just 33% of those who did receive POCUS training reported feeling competent to use POCUS independently. Similarly, just 23% of training program directors/associate program directors indicated that they had a POCUS curriculum in place, although 74% of training program directors and associate program directors indicated that a program was in development or that there was interest in creating a POCUS curriculum. Most fellow and faculty respondents rated commonly covered POCUS topics-including dialysis access imaging and kidney biopsy-as "important" or "very important," with the greatest interest in diagnostic kidney ultrasound. Guided scanning with an instructor was the highest-rated teaching strategy. The most frequently reported barrier to POCUS program development was the lack of available instructors. CONCLUSIONS: Despite high trainee and faculty interest in POCUS, the majority of current nephrology fellows are not receiving POCUS training. Hands-on training guided by an instructor is highly valued, yet availability of adequately trained instructors remains a barrier to program development. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_09_21_CJN01850222.mp3.

Assessing Nephrology Fellows' Skills in Communicating About Kidney Replacement Therapy and Kidney Biopsy: A Multicenter Clinical Simulation Study on Breaking Bad News.

RATIONALE & OBJECTIVE: Interpersonal communication skills and professionalism competencies are difficult to assess among nephrology trainees. We developed a formative "Breaking Bad News" simulation and implemented a study in which nephrology fellows were assessed with regard to their skills in providing counseling to simulated patients confronting the need for kidney replacement therapy (KRT) or kidney biopsy. STUDY DESIGN: Observational study of communication competency in the setting of preparing for KRT for kidney failure, for KRT for acute kidney injury (AKI), or for kidney biopsy. SETTING & PARTICIPANTS: 58 first- and second-year nephrology fellows assessed during 71 clinical evaluation sessions at 8 training programs who participated in an objective structured clinical examination of simulated patients in 2017 and 2018. PREDICTORS: Fellowship training year and clinical scenario. OUTCOME: Primary outcome was the composite score for the "overall rating" item on the Essential Elements of Communication-Global Rating Scale 2005 (EEC-GRS), as assessed by simulated patients. Secondary outcomes were the score for EEC-GRS "overall rating" item for each scenario, score < 3 for any EEC-GRS item, Mini-Clinical Examination Exercise (Mini-CEX) score < 3 on at least 1 item (as assessed by faculty), and faculty and fellow satisfaction with simulation exercise (via a survey they completed). ANALYTICAL APPROACH: Nonparametric tests of hypothesis comparing performance by fellowship year (primary goal) and scenario. RESULTS: Composite scores for EEC-GRS overall rating item were not significantly different between fellowship years (P = 0.2). Only 4 of 71 fellow evaluations had an unsatisfactory score for the EEC-GRS overall rating item on any scenario. On Mini-CEX, 17% scored < 3 on at least 1 item in the kidney failure scenario; 37% and 53% scored < 3 on at least 1 item in the AKI and kidney biopsy scenarios, respectively. In the survey, 96% of fellows and 100% of faculty reported the learning objectives were met and rated the experience good or better in 3 survey rating questions. LIMITATIONS: Relatively brief time for interactions; limited familiarity with and training of simulated patients in use of EEC-GRS. CONCLUSIONS: The fellows scored highly on the EEC-GRS regardless of their training year, suggesting interpersonal communication competency is achieved early in training. The fellows did better with the kidney failure scenario than with the AKI and kidney biopsy scenarios. Structured simulated clinical examinations may be useful to inform curricular choices and may be a valuable assessment tool for communication and professionalism.

Renal Functional Outcomes after Surgery, Ablation, and Active Surveillance of Localized Renal Tumors: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVES: Management strategies for localized renal masses suspicious for renal cell carcinoma include radical nephrectomy, partial nephrectomy, thermal ablation, and active surveillance. Given favorable survival outcomes across strategies, renal preservation is often of paramount concern. To inform clinical decision making, we performed a systematic review and meta-analysis of studies comparing renal functional outcomes for radical nephrectomy, partial nephrectomy, thermal ablation, and active surveillance. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1997 to May 1, 2015 to identify comparative studies reporting renal functional outcomes. Meta-analyses were performed for change in eGFR, incidence of CKD, and AKI. RESULTS: We found 58 articles reporting on relevant renal functional outcomes. Meta-analyses showed that final eGFR fell 10.5 ml/min per 1.73 m2 lower for radical nephrectomy compared with partial nephrectomy and indicated higher risk of CKD stage 3 or worse (relative risk, 2.56; 95% confidence interval, 1.97 to 3.32) and ESRD for radical nephrectomy compared with partial nephrectomy. Overall risk of AKI was similar for radical nephrectomy and partial nephrectomy, but studies suggested higher risk for radical nephrectomy among T1a tumors (relative risk, 1.37; 95% confidence interval, 1.13 to 1.66). In general, similar findings of worse renal function for radical nephrectomy compared with thermal ablation and active surveillance were observed. No differences in renal functional outcomes were observed for partial nephrectomy versus thermal ablation. The overall rate of ESRD was low among all management strategies (0.4%-2.8%). CONCLUSIONS: Renal functional implications varied across management strategies for localized renal masses, with worse postoperative renal function for patients undergoing radical nephrectomy compared with other strategies and similar outcomes for partial nephrectomy and thermal ablation. Further attention is needed to quantify the changes in renal function associated with active surveillance and nephron-sparing approaches for patients with preexisting CKD.

Inflammatory Markers and Risk for Cognitive Decline in Chronic Kidney Disease: The CRIC Study.

INTRODUCTION: Chronic kidney disease (CKD) is associated with an increased risk of cognitive decline, but the mechanisms remain poorly defined. We sought to determine the relation between serum inflammatory markers and risk of cognitive decline among adults with CKD. METHODS: We studied 757 adults aged ≥55 years with CKD participating in the Chronic Renal Insufficiency Cohort Cognitive study. We measured interleukin (IL)-1ß, IL-1 receptor antagonist, IL-6, tumor necrosis factor (TNF)-α, high-sensitivity C-reactive protein (hs-CRP), and fibrinogen in baseline plasma samples. We assessed cognitive function at regular intervals in 4 domains and defined incident impairment as a follow-up score more than 1 SD poorer than the group mean. RESULTS: The mean age of the sample was 64.3 ± 5.6 years, and the mean follow-up was 6.2 ± 2.5 years. At baseline, higher levels of each inflammatory marker were associated with poorer age-adjusted performance. In analyses adjusted for baseline cognition, demographics, comorbid conditions, and kidney function, participants in the highest tertile of hs-CRP, the highest tertile of fibrinogen, and the highest tertile of IL-1ß had an increased risk of impairment in attention compared to participants in the lowest tertile of each marker. Participants in the highest versus lowest tertile of TNF-α had a lower adjusted risk of impairment in executive function. There was no association between other inflammatory markers and change in cognitive function. DISCUSSION: Among adults with CKD, higher levels of hs-CRP, fibrinogen, and IL-1ß were associated with a higher risk of impairment in attention. Higher levels of TNF-α were associated with a lower risk of impaired executive function.

Intravenous iron administration strategies and anemia management in hemodialysis patients.

Background: The effect of maintenance intravenous (IV) iron administration on subsequent achievement of anemia management goals and mortality among patients recently initiating hemodialysis is unclear. Methods: We performed an observational cohort study, in adult incident dialysis patients starting on hemodialysis. We defined IV administration strategies over a 12-week period following a patient's initiation of hemodialysis; all those receiving IV iron at regular intervals were considered maintenance, and all others were considered non-maintenance. We used multivariable models adjusting for demographics, clinical and treatment parameters, iron dose, measures of iron stores and pro-infectious and pro-inflammatory parameters to compare these strategies. The outcomes under study were patients' (i) achievement of hemoglobin (Hb) of 10-12 g/dL, (ii) more than 25% reduction in mean weekly erythropoietin stimulating agent (ESA) dose and (iii) mortality, ascertained over a period of 4 weeks following the iron administration period. Results: Maintenance IV iron was administered to 4511 patients and non-maintenance iron to 8458 patients. Maintenance IV iron administration was not associated with a higher likelihood of achieving an Hb between 10 and 12 g/dL {adjusted odds ratio (OR) 1.01 [95% confidence interval (CI) 0.93-1.09]} compared with non-maintenance, but was associated with a higher odds of achieving a reduced ESA dose of 25% or more [OR 1.33 (95% CI 1.18-1.49)] and lower mortality [hazard ratio (HR) 0.73 (95% CI 0.62-0.86)]. Conclusions: Maintenance IV iron strategies were associated with reduced ESA utilization and improved early survival but not with the achievement of Hb targets.

Distinguishing malignant and benign renal masses with composite models and nomograms: A systematic review and meta-analysis of clinically localized renal masses suspicious for malignancy.

Solid renal masses and cystic lesions with solid components are suspicious for renal cell carcinoma. Without an effective screening test, composite models and nomograms rely on patient and tumor characteristics to stratify the risk of benign disease versus malignant disease. To guide decisions about the use of renal mass sampling or excision, a systematic review and meta-analysis of the ability of composite models to predict the likelihood of malignancy on the basis of preoperative clinical variables was performed. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from January 1, 1997, through May 1, 2015, according to the Preferred Reporting Items for Systematic Review and Meta-Analyses statement. Composite models necessarily included imaging results and at least 1 element from the following to be compared with surgical pathology: demographic characteristics, clinical characteristics, and blood or urine tests. Two independent reviewers screened citations and extracted data. Quality Assessment Tool for Diagnostic Accuracy Studies 2 was used to assess the risk of bias. The strength of evidence was graded with the scheme recommended by Methods Guide for Effectiveness and Comparative Effectiveness Reviews. Twenty studies (12,149 patients) were included in this review. The only significant predictors of malignancy in the composite models were tumor size (effect size, 1.33-fold increased risk per centimeter; 95% confidence interval [CI], 1.22-1.43) and male sex (effect size, 2.71; 95% CI, 2.39-3.02). The results were inconclusive or not significant for tumor characteristics, age, body mass index, and incidental presentation. In conclusion, composite models currently have a limited ability to distinguish malignant renal masses from benign renal masses, with increased tumor size and male sex associated with malignancy. Cancer 2016;122:3267-3276. © 2016 American Cancer Society.

A Systematic Review of Research Gaps in the Evaluation and Management of Localized Renal Masses.

The management of clinically localized renal masses suspicious for renal cell carcinoma varies, partially because of gaps in the evidence base. We conducted a systematic review to summarize research gaps for the evaluation of composite models for predicting malignancy; use of percutaneous renal sampling for diagnosis; and comparative effectiveness of surgery, thermal ablation, and active surveillance. A total of 147 studies, published in 150 articles, were identified. To promote improved patient care and health outcomes, we recommend incorporation of emerging biomarkers into validated composite models, standardization of biopsy protocols, standard reporting of clinical stage, and performance of prospective studies with objective selection criteria.

The Associations between Peripheral Artery Disease and Physical Outcome Measures in Men and Women with Chronic Kidney Disease.

BACKGROUND: Peripheral artery disease (PAD) is highly prevalent and associated with significant morbidity and mortality, but sex-based differences are incompletely understood. We sought to define the associations between PAD and physical outcome measures and to determine if these associations differed by sex in the Chronic Renal Insufficiency Cohort. METHODS: Among 3,543 participants, we assessed the cross-sectional relationship between PAD severity defined by ankle-brachial index; and (1) physical activity (metabolic equivalent [MET]-hr/wk), (2) walking pace (slow versus medium and/or fast), and (3) physical function (12-item Short Form Health Survey [SF-12]) at baseline. RESULTS: In a multivariable linear regression model, PAD severity was not associated with physical activity defined by total MET-hr per wk in men or women (P = 0.432). However, PAD severity was significantly associated with walking activity (P = 0.037), although this relationship did not differ by sex (P = 0.130). Similarly, PAD severity was significantly associated with walking pace (P < 0.001), although this relationship did not differ by sex (P = 0.086). In contrast, there was an independent association between PAD severity and SF-12 (P = 0.018), with a significant interaction by sex (P < 0.001). CONCLUSIONS: These data suggest that tools used to evaluate the functional consequences of PAD should focus on walking activity and walking pace, as well as physical function, where sex-specific associations should be accounted for.

Management of Renal Masses and Localized Renal Cancer: Systematic Review and Meta-Analysis.

PURPOSE: Several options exist for management of clinically localized renal masses suspicious for cancer, including active surveillance, thermal ablation and radical or partial nephrectomy. We summarize evidence on effectiveness and comparative effectiveness of these treatment approaches for patients with a renal mass suspicious for localized renal cell carcinoma. MATERIALS AND METHODS: We searched MEDLINE®, Embase® and the Cochrane Central Register of Controlled Trials from January 1, 1997 through May 1, 2015. Paired investigators independently screened articles to identify controlled studies of management options or cohort studies of active surveillance, abstracted data sequentially and assessed risk of bias independently. Strength of evidence was graded by comparisons. RESULTS: The search identified 107 studies (majority T1, no active surveillance or thermal ablation stratified outcomes of T2 tumors). Cancer specific survival was excellent among all management strategies (median 5-year survival 95%). Local recurrence-free survival was inferior for thermal ablation with 1 treatment but reached equivalence to other modalities after multiple treatments. Overall survival rates were similar among management strategies and varied with age and comorbidity. End-stage renal disease rates were low for all strategies (0.4% to 2.8%). Radical nephrectomy was associated with the largest decrease in estimated glomerular filtration rate and highest incidence of chronic kidney disease. Thermal ablation offered the most favorable perioperative outcomes. Partial nephrectomy showed the highest rates of urological complications but overall rates of minor/major complications were similar among interventions. Strength of evidence was moderate, low and insufficient for 11, 22 and 30 domains, respectively. CONCLUSIONS: Comparative studies demonstrated similar cancer specific survival across management strategies, with some differences in renal functional outcomes, perioperative outcomes and postoperative harms that should be considered when choosing a management strategy.

Diagnostic Accuracy and Risks of Biopsy in the Diagnosis of a Renal Mass Suspicious for Localized Renal Cell Carcinoma: Systematic Review of the Literature.

PURPOSE: Clinical practice varies widely on the diagnostic role of biopsy for clinically localized renal masses suspicious for renal cell carcinoma. Therefore, we performed a systematic review of the available literature to quantify the accuracy and rate of adverse events of renal mass biopsy. MATERIALS AND METHODS: MEDLINE®, Embase® and the Cochrane databases were searched (January 1997 to May 2015) for relevant studies. The systematic review process established by the Agency for Healthcare Research and Quality was followed. Nondiagnostic biopsies were excluded from diagnostic accuracy calculations. RESULTS: A total of 20 studies with 2,979 patients and 3,113 biopsies were included in the study. The overall nondiagnostic rate was 14.1% with 90.4% of those undergoing surgery found to have malignancy. Repeat biopsy led to diagnosis in 80% of patients. The false-positive rate was low (4.0%), histological and renal cell carcinoma subtype concordance was substantial, and Fuhrman upgrading notable (16%) from low grade (1 to 2) to high grade (3 to 4). Core biopsy was highly sensitive (97.5%, CI 96.5-98.5) and specific (96.2%, CI 90.7-100) when a diagnostic result was obtained, but most patients (∼80%) did not undergo surgery after a benign biopsy. Among patients undergoing extirpation 36.7% with a negative biopsy had malignant disease on surgical pathology (negative predictive value 63.3%, CI 52.4-74.2). Direct complications included hematoma (4.9%), clinically significant pain (1.2%), gross hematuria (1.0%), pneumothorax (0.6%) and hemorrhage (0.4%). CONCLUSIONS: Diagnostic accuracy was generally high for biopsy of localized renal masses with a low complication rate, but the nondiagnostic rate and negative predictive value were concerning. Renal mass sampling should be used judiciously as further research will determine its true clinical utility.

Effect of intravenous iron use on hospitalizations in patients undergoing hemodialysis: a comparative effectiveness analysis from the DEcIDE-ESRD study.

BACKGROUND: Intravenous iron use in hemodialysis patients has greatly increased over the last decade, despite limited studies on the safety of iron. METHODS: We studied the association of receipt of intravenous iron with hospitalizations in an incident cohort of hemodialysis patients. We examined 9544 patients from Dialysis Clinic, Inc. (DCI). We ascertained intravenous iron use from DCI electronic medical record and USRDS data files, and hospitalizations through Medicare claims. We examined the association between iron exposure accumulated over 1-, 3- or 6-month time windows and incident hospitalizations in the follow-up period using marginal structural models accounting for time-dependent confounders. We performed sensitivity analyses including recurrent events models for multiple hospitalizations and models for combined outcome of hospitalization and death. RESULTS: There were 22 347 hospitalizations during a median follow-up of 23 months. Higher cumulative dose of intravenous iron was not associated with all-cause, cardiovascular or infectious hospitalizations [HR 0.97 (95% CI: 0.77-1.22) for all-cause hospitalizations comparing >2100 mg versus 0-900 mg of iron over 6 months]. Findings were similar in models examining the risk of hospitalizations in 1- and 3-month windows [HR 0.88 (95% CI: 0.79-0.99) and HR 0.88 (95% CI: 0.74-1.03), respectively] or the risk of combined outcome of hospitalization and death in the 6-month window [HR 0.98 (95% CI: 0.78-1.23)]. CONCLUSIONS: Higher cumulative dose of intravenous iron may not be associated with increased risk of hospitalizations in hemodialysis patients. While clinical trials are needed, employing higher iron doses to reduce erythropoiesis-stimulating agents does not appear to increase morbidity in routine clinical care.

Intravenous iron exposure and mortality in patients on hemodialysis.

BACKGROUND AND OBJECTIVES: Clinical trials assessing effects of larger cumulative iron exposure with outcomes are lacking, and observational studies have been limited by assessment of short-term exposure only and/or failure to assess cause-specific mortality. The associations between short- and long-term iron exposure on all-cause and cause-specific mortality were examined. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The study included 14,078 United States patients on dialysis initiating dialysis between 2003 and 2008. Intravenous iron dose accumulations over 1-, 3-, and 6-month rolling windows were related to all-cause, cardiovascular, and infection-related mortality in Cox proportional hazards models that used marginal structural modeling to control for time-dependent confounding. RESULTS: Patients in the 1-month model cohort (n=14,078) were followed a median of 19 months, during which there were 27.6% all-cause deaths, 13.5% cardiovascular deaths, and 3% infection-related deaths. A reduced risk of all-cause mortality with receipt of >150-350 (hazard ratio, 0.78; 95% confidence interval, 0.64 to 0.95) or >350 mg (hazard ratio, 0.79; 95% confidence interval, 0.62 to 0.99) intravenous iron compared with >0-150 mg over 1 month was observed. There was no relation of 1-month intravenous iron dose with cardiovascular or infection-related mortality and no relation of 3- or 6-month cumulative intravenous iron dose with all-cause or cardiovascular mortality. There was a nonstatistically significant increase in infection-related mortality with receipt of >1050 mg intravenous iron in 3 months (hazard ratio, 1.69; 95% confidence interval, 0.87 to 3.28) and >2100 mg in 6 months (hazard ratio, 1.59; 95% confidence interval, 0.73 to 3.46). CONCLUSIONS: Among patients on incident dialysis, receipt of ≤ 1050 mg intravenous iron in 3 months or 2100 mg in 6 months was not associated with all-cause, cardiovascular, or infection-related mortality. However, nonstatistically significant findings suggested the possibility of infection-related mortality with receipt of >1050 mg in 3 months or >2100 mg in 6 months. Randomized clinical trials are needed to assess the safety of exposure to greater cumulative intravenous iron doses.

Incidental findings on cardiac computed tomography in incident hemodialysis patients: the predictors of arrhythmic and cardiovascular events in end-stage renal disease (PACE) study.

BACKGROUND: This is the first study that has examined non-cardiac incidental findings in research cardiac computed tomography (CT) of hemodialysis patients and their relationship with patient characteristics. METHODS: We performed a cross-sectional analysis in the Predictors of Arrhythmic and Cardiovascular Events in End-Stage Renal Disease (PACE) study, a prospective cohort study on incident hemodialysis patients. Non-cardiac structures in the cardiac CT scan were reviewed and evaluated. The type and frequencies of non-cardiac incidental CT findings were summarized. Univariate and multivariate logistic regression were performed to analyze the associations between gender, older age, obesity, history of cardiovascular disease (CVD), smoking status, history of chronic pulmonary disease and history of cancer with presence of any incidental CT findings and, separately, pulmonary nodules. RESULTS: Among the 260 participants, a total of 229 non-cardiac incidental findings were observed in 145 participants (55.8% of all participants). Of these findings, pulmonary nodules were the most common incidental finding (24.2% of all findings), and 41.3% of them requiring further follow-up imaging per radiology recommendation. Vascular and gastrointestinal findings occurred in 11.8% and 15.3% of participants, respectively. Participants 65 years or older had a higher odds of any incidental findings (Odds Ratio (OR) =2.55; 95% Confidence Intervals (CI) 1.30, 4.99) and pulmonary nodules (OR=4.80; 95% CI 2.51, 9.18). Prior history of CVD was independently and significantly associated with any incidental findings (OR=2.00; 95% CI 1.19, 3.40); but not with the presence of pulmonary nodules. CONCLUSIONS: We demonstrate that the prevalence of incidental findings by cardiac CT scanning is extremely high among patients on hemodialysis. Further investigations to follow-up on the high occurrence of incidental findings during our research study and potentially clinical studies raises important practical, ethical and medico-legal issues that need to be carefully considered in research projects using imaging studies.

Biomarkers of vascular calcification and mortality in patients with ESRD.

BACKGROUND: Vascular calcification is common among patients undergoing dialysis and is associated with mortality. Factors such as osteoprotegerin (OPG), osteopontin (OPN), bone morphogenic protein-7 (BMP-7), and fetuin-A are involved in vascular calcification. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: OPG, OPN, BMP-7, and fetuin-A were measured in blood samples from 602 incident dialysis patients recruited from United States dialysis centers between 1995 and 1998 as part of the Choices for Healthy Outcomes In Caring for ESRD Study. Their association with all-cause and cardiovascular mortality were assessed using Cox proportional hazards models adjusted for demographic characteristics, comorbidity, serum phosphate, and calcium. An interaction with diabetes was tested because of its known association with vascular calcification. Predictive accuracy of selected biomarkers was explored by C-statistics in nested models with training and validation subcohorts. RESULTS: Higher OPG and lower fetuin-A levels were associated with higher mortality over up to 13 years of follow-up (median, 3.4 years). The adjusted hazard ratios (HR) for highest versus lowest tertile were 1.49 (95% confidence interval [95% CI], 1.08 to 2.06) for OPG and 0.69 (95% CI, 0.52 to 0.92) for fetuin-A. In stratified models, the highest tertile of OPG was associated with higher mortality among patients without diabetes (HR, 2.42; 95% CI, 1.35 to 4.34), but not patients with diabetes (HR, 1.26; 95% CI, 0.82 to 1.93; P for interaction=0.001). In terms of cardiovascular mortality, higher fetuin-A was associated with lower risk (HR, 0.85 per 0.1 g/L: 95% CI, 0.75 to 0.96). In patients without diabetes, higher OPG was associated with greater risk (HR for highest versus lowest tertile, 2.91; 95% CI, 1.06 to 7.99), but not in patients with diabetes or overall. OPN and BMP-7 were not independently associated with outcomes overall. The addition of OPG and fetuin-A did not significantly improve predictive accuracy of mortality. CONCLUSIONS: OPG and fetuin-A may be risk factors for all-cause and cardiovascular mortality in patients undergoing dialysis, but do not improve risk prediction.

Plant protein intake is associated with fibroblast growth factor 23 and serum bicarbonate levels in patients with chronic kidney disease: the Chronic Renal Insufficiency Cohort study.

BACKGROUND: Protein from plant, as opposed to animal, sources may be preferred in chronic kidney disease (CKD) because of the lower bioavailability of phosphate and lower nonvolatile acid load. STUDY DESIGN: Observational cross-sectional study. SETTING AND PARTICIPANTS: A total of 2,938 participants with CKD and information on their dietary intake at the baseline visit in the Chronic Renal Insufficiency Cohort Study. PREDICTORS: Percentage of total protein intake from plant sources (percent plant protein) was determined by scoring individual food items using the National Cancer Institute Diet History Questionnaire (DHQ). OUTCOMES: Metabolic parameters, including serum phosphate, bicarbonate (HCO3), potassium, and albumin, plasma fibroblast growth factor 23 (FGF-23), and parathyroid hormone (PTH), and hemoglobin levels. MEASUREMENTS: We modeled the association between percent plant protein and metabolic parameters using linear regression. Models were adjusted for age, sex, race, diabetes status, body mass index, estimated glomerular filtration rate, income, smoking status, total energy intake, total protein intake, 24-hour urinary sodium concentration, use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and use of diuretics. RESULTS: Higher percent plant protein was associated with lower FGF-23 (P = .05) and higher HCO3 (P = .01) levels, but not with serum phosphate or parathyroid hormone concentrations (P = .9 and P = .5, respectively). Higher percent plant protein was not associated with higher serum potassium (P = .2), lower serum albumin (P = .2), or lower hemoglobin (P = .3) levels. The associations of percent plant protein with FGF-23 and HCO3 levels did not differ by diabetes status, sex, race, CKD stage (2/3 vs. 4/5), or total protein intake (≤0.8 g/kg/day vs. >0.8 g/kg/day; P-interaction >.10 for each). LIMITATIONS: This is a cross-sectional study; determination of percent plant protein using the Diet History Questionnaire has not been validated. CONCLUSIONS: Consumption of a higher percentage of protein from plant sources may lower FGF-23 and raise HCO3 levels in patients with CKD.

Inflammation and the paradox of racial differences in dialysis survival.

African Americans experience a higher mortality rate and an excess burden of ESRD compared with Caucasians in the general population, but among those treated with dialysis, African Americans typically survive longer than Caucasians. We examined whether differences in inflammation may explain this paradox. We prospectively followed a national cohort of incident dialysis patients in 81 clinics for a median of 3 years (range 4 months to 9.5 years). Among 554 Caucasians and 262 African Americans, we did not detect a significant difference in median CRP between African Americans and Caucasians (3.4 versus 3.9 mg/L). Mortality was significantly lower for African Americans versus Caucasians (34% versus 56% at 5 years); the relative hazard was 0.7 (95% CI, 0.5 to 0.9) after adjusting for age, gender, dialysis modality, smoking, body mass index, diabetes, BP, cholesterol, cardiovascular disease, congestive heart failure, comorbid disease, hemoglobin, albumin, CRP, and IL-6. However, the risk varied by CRP tertile: the relative hazards for African Americans compared with Caucasians were 1.0 (95% CI, 0.7 to 1.4), 0.7 (95% CI, 0.4 to 1.3), and 0.5 (95% CI, 0.3 to 0.8) in the lowest, middle, and highest tertiles, respectively. We obtained similar results when we accounted for transplantation as a competing event, and we examined mortality across tertiles of IL-6. In summary, racial differences in survival among dialysis patients are not present at low levels of inflammation but are large at higher levels. Differences in inflammation may explain, in part, the racial paradox of ESRD survival.

Results of repeat renal transplantation after graft loss from BK virus nephropathy.

BACKGROUND: BK virus nephropathy (BKVN) is an important cause of renal graft loss in recent years. The aims of this study are to (1) describe the management of patients undergoing retransplantation after allograft loss in the setting of BKVN and (2) to identify risk factors for BK virus replication in the retransplant. METHODS: This retrospective study compiled data on adult patients undergoing repeat transplantation after previous loss of allograft to BKVN from six U.S. centers. Clinical, laboratory, and histopathologic data for both the transplant that failed because of BKVN and the retransplant were abstracted and reviewed. RESULTS: A total of 31 patients underwent retransplantation after a median of 6 months after failure of the first allograft, with 10 of 31 undergoing preemptive retransplantation. Twenty-six patients had documented clearance of viremia and 13 underwent transplant nephrectomy before the retransplant. Two of six centers had changed immunosuppression protocols for the retransplants. After repeat transplant, 11 (35%) had BKV replication in urine and plasma with two patients experiencing BKVN. Seven had acute rejection. In univariate analysis, documented viremia clearance after BKVN in the initial transplant was significantly associated with the absence of BKV replication after repeat transplantation. Serum creatinine was significantly higher at 1 year in patients with BKV replication. One graft loss occurred due to rejection. CONCLUSIONS: Retransplantation is safe and effective for patients with previous graft loss due to BKVN preferably post-BK viral clearance.

Hemodynamic correlates of proteinuria in chronic kidney disease.

BACKGROUND AND OBJECTIVES: Brachial artery measures of BP are associated with increasing degrees of proteinuria. Whether central measures of BP or vascular stiffness are associated with increased risk of proteinuria in patients with chronic kidney disease (CKD) is unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Measurements of central and brachial artery BP, and aortic pulse wave velocity (PWV) were performed in a cross-sectional cohort of patients with CKD (n = 2144) from the Chronic Renal Insufficiency Cohort (CRIC) study to determine factors which predict increased risk of proteinuria. Multivariate analysis stratified by diabetes included age, ethnicity, gender, estimated glomerular filtration rate (GFR), waistline, smoking, heart rate, and medications to evaluate the relationship of hemodynamic factors and proteinuria. RESULTS: Brachial artery systolic BP (SBP) was important as an explanatory factor for variations in proteinuria among both diabetics (R(2) = 0.40, P < 0.0001) and non diabetics (R(2) = 0.38, P < 0.001). Measures of peripheral pulse pressure (PP), central SBP, and central pulse pressure added little to the explained variation in proteinuria beyond brachial artery SBP, whereas PWV as a measure of vascular stiffness incrementally accounted for a significant portion of variation in proteinuria beyond that explained by brachial artery SBP in diabetics (R(2) = 0.42, P < 0.001) but not non diabetics. CONCLUSIONS: Brachial artery SBP and PWV are both associated with variations in proteinuria in patients with CKD.