Randomized Controlled Trials 2: Analysis.

When analyzing the results of a trial, the primary outcome variable must be kept in clear focus. In the analysis plan, consideration must be given to comparing the characteristics of the subjects, taking account of differences in these characteristics, intention-to-treat analysis, interim analyses and stopping rules, mortality comparisons, composite outcomes, research design including run-in periods, factorial, stratified and crossover designs, number needed to treat, power issues, multivariate modeling, subgroup analysis, competing risks, and hypothesis-generating analyses.

Randomized Controlled Trials 4: Planning, Analysis, and Interpretation of Quality-of-Life Studies.

Quality-of-life (QoL) outcomes are important elements of randomized controlled trials. The instruments for measurement of QoL vary but usually multiple comparisons are possible, a concern that can be offset by prespecifying the outcomes of interest. Missing data may threaten the validity of QoL assessments in trials. Therefore, familiarity with the strategies used to account for missing data is necessary. Measures that incorporate both survival and QoL are helpful for treatment decisions. The definition of minimal clinically important differences in QoL scores is important and often derived using inadequate methods.

Time to thrombectomy is associated with increased risk for dialysis catheter placement.

BACKGROUND: Arteriovenous dialysis access, fistulae (AVF) or grafts (AVG), are associated with significant rates of thrombosis. Timely thrombectomy may have a significant impact on immediate and long-term access survival. However, switching to a catheter is associated with higher rates of morbidity and mortality compared with those who have an AVF or AVG. OBJECTIVES: The goal of this study was to evaluate whether time to thrombectomy increases the risk for loss of dialysis access and subsequent placement of a dialysis catheter at hospital discharge, at 6 months, 12 months, and data at any time after discharge. METHODS: Using retrospective data, 444 patients were identified as having undergone thrombectomy for dialysis access dysfunction between January 2008 and April 2015, with 122 hospital admissions primarily for thrombectomy. RESULTS: The mean age was 60.4 years, 65% were male, and 44.3% had an arteriovenous fistula as their dialysis access. The mean time to thrombectomy was 10.8 hours, and 14 patients utilised a catheter for haemodialysis as primary access upon discharge. After adjustment for prior access intervention, access type, and time to thrombectomy, the adjusted odds ratios (AOR) of a one-day delay in thrombectomy was associated with a twofold increase in requirement for catheter at discharge and at 6 months. This association remained present at any time after discharge. CONCLUSION: In this study of patients cared for within an academic health system, a single day delay in thrombectomy nearly doubled the risk of needing a dialysis catheter at hospital discharge, 6 months, or any time after discharge.

Trends in Angiotensin-Converting Enzyme Inhibitor and Angiotensin II Receptor Blocker Use among Those with Impaired Kidney Function in the United States.

BACKGROUND: Although hypertension is common in CKD and evidence-based treatment of hypertension has changed considerably, contemporary and nationally representative information about use of angiotensin-converting enzyme (ACEs) inhibitors or angiotensin II receptor blockers (ARBs) in CKD is lacking. METHODS: We examined ACE/ARB trends from 1999 to 2014 among 38,885 adult National Health and Nutrition Examination Survey participants with creatinine-based eGFR<60 ml/min per 1.73 m2 or urinary albumin-to-creatinine ratio ≥30 mg/g. RESULTS: Of 7085 participants with CKD, 34.9% used an ACE/ARB. Across four eras studied, rates of use rose significantly (rates were 25.5% in 1999-2002, 33.3% in 2003-2006, 39.0% in 2007-2010, and 40.1% in 2011-2014) but appeared to plateau after 2003. Among those with CKD, use was significantly greater among non-Hispanic white and black individuals (36.1% and 38.2%, respectively) and lower among Hispanic individuals (26.7%) and other races/ethnicities (29.3%). In age-, sex-, and race/ethnicity-adjusted models, ACE/ARB use was significantly associated with era (adjusted odds ratios [aOR], 1.41; 95% confidence interval [95% CI], 1.14 to 1.74 for 2003-2006, 1.84; 95% CI, 1.48 to 2.28 for 2007-2010, and 2.02; 95% CI, 1.61 to 2.53 for 2011-2014 versus 1999-2002); it also was significantly associated with non-Hispanic black versus non-Hispanic white race/ethnicity (aOR, 1.40; 95% CI, 1.19 to 1.66). Other multivariate associations included older age, men, elevated BMI, diabetes mellitus, treated hypertension, cardiac failure, myocardial infarction, health insurance, and receiving medical care within the prior year. CONCLUSIONS: Rates of ACE/ARB use increased in the early 2000s among United States adults with CKD, but for unclear reasons, use appeared to plateau in the ensuing decade. Research examining barriers to care and other factors is needed.

The impact of outpatient acute kidney injury on mortality and chronic kidney disease: a retrospective cohort study.

BACKGROUND: Acute kidney injury (AKI) has been extensively studied in hospital settings. Limited data exist regarding outcomes for patients with outpatient AKI who are not subsequently admitted. We investigated whether outpatient AKI, defined by a 50% increase in creatinine (Cr), is associated with increased mortality and renal events. METHODS: In this retrospective study, outpatient serum Cr values from adults receiving primary care at a health system during an 18-month exposure period were used to categorize patients into one of five groups (no outpatient AKI, outpatient AKI with recovery, outpatient AKI without recovery, outpatient AKI without repeat Cr and no Cr). Principal outcomes of all-cause mortality and renal events (50% decline in estimated glomerular filtration rate to <30 mL/min/1.73 m2) were examined using Cox proportional hazards models. RESULTS: Among 384 869 eligible patients, 51% had at least one Cr measured during the exposure period. Outpatient AKI occurred in 1.4% of patients while hospital AKI occurred in only 0.3% of patients. The average follow-up was 5.3 years. Outpatient AKI was associated with an increased risk of all-cause mortality {adjusted hazard ratio [aHR] 1.90 [95% confidence interval (CI) 1.76-2.06]} and results were consistent across all AKI groups. Outpatient AKI was also associated with an increased risk of renal events [aHR 1.33 (95% CI 1.11-1.59)], even among those who recovered. CONCLUSIONS: Outpatient AKI is more prevalent than inpatient AKI and is a risk factor for all-cause mortality and renal events, even among those who recover kidney function. Further research is necessary to determine risk factors and identify strategies for preventing outpatient AKI.

Design of a clinical risk calculator for major clinical outcomes in patients with atherosclerotic renovascular disease.

BACKGROUND: Risk stratification in atherosclerotic renovascular disease (ARVD) can influence treatment decisions and facilitate patient selection for revascularization. In this study, we aim to use variables with the best predictive value to design a risk calculator that can assist clinicians with risk stratification and outcome prediction. METHODS: Patients with a radiological diagnosis of ARVD referred to our tertiary renal centre were recruited into this prospective cohort study between 1986 and 2014. Primary clinical endpoints included: death, progression to end-stage kidney disease and cardiovascular events (CVE). A stepwise regression model was used to select variables with the most significant hazard ratio for each clinical endpoint. The risk calculator was designed using Hypertext Markup Language. Survival and CVE-free survival were estimated at 1, 5 and 10 years. RESULTS: In total, 872 patients were recruited into the Salford ARVD study with a median follow-up period of 54.9 months (interquartile range 20.2-96.0). Only models predicting death and CVE showed good performance (C-index >0.80). Survival probabilities obtained from the risk calculator show that most patients with ARVD have reduced long-term survival. Revascularization improved outcomes in patients with higher baseline estimated glomerular filtration rate and lower proteinuria but not in those with co-existing comorbidities and higher levels of baseline proteinuria. CONCLUSIONS: Although this risk calculator requires further independent validation in other ARVD cohorts, this study shows that a small number of easily obtained variables can help predict clinical outcomes and encourage a patient-specific therapeutic approach.

Race, Ethnicity, and End-of-Life Care in Dialysis Patients in the United States.

BACKGROUND: End-of-life care is a prominent consideration in patients on maintenance dialysis, especially when death appears imminent and quality of life is poor. To date, examination of race- and ethnicity-associated disparities in end-of-life care for patients with ESRD has largely been restricted to comparisons of white and black patients. METHODS: We performed a retrospective national study using United States Renal Data System files to determine whether end-of-life care in United States patients on dialysis is subject to racial or ethnic disparity. The primary outcome was a composite of discontinuation of dialysis and death in a nonhospital or hospice setting. RESULTS: Among 1,098,384 patients on dialysis dying between 2000 and 2014, the primary outcome was less likely in patients from any minority group compared with the non-Hispanic white population (10.9% versus 22.6%, P<0.001, respectively). We also observed similar significant disparities between any minority group and non-Hispanic whites for dialysis discontinuation (16.7% versus 31.2%), as well as hospice (10.3% versus 18.1%) and nonhospital death (34.4% versus 46.4%). After extensive covariate adjustment, the primary outcome was less likely in the combined minority group than in the non-Hispanic white population (adjusted odds ratio, 0.55; 95% confidence interval, 0.55 to 0.56; P<0.001). Individual minority groups (non-Hispanic Asian, non-Hispanic black, non-Hispanic Native American, and Hispanic) were significantly less likely than non-Hispanic whites to experience the primary outcome. This disparity was especially pronounced for non-Hispanic Native American and Hispanic subgroups. CONCLUSIONS: There appear to be substantial race- and ethnicity-based disparities in end-of-life care practices for United States patients receiving dialysis.

End-Stage Kidney Disease From Scleroderma in the United States, 1996 to 2012.

INTRODUCTION: Although the management of scleroderma continues to evolve, it is unknown whether the burden of end-stage kidney disease (ESKD) treated with maintenance renal replacement therapy from SD has changed. METHODS: We examined United States Renal Data System data (n = 1,677,303) for the years 1996 to 2012 to quantify the incidence and outcomes of ESKD from scleroderma treated with renal replacement therapy (n = 2398). Outcomes assessed through demography-matched scleroderma-positive/scleroderma-negative comparisons included recovery of kidney function, mortality, listing for transplant, renal transplantations, and graft failure. RESULTS: Overall ESKD rates from scleroderma were 0.5 per million per year. Adjusted incidence ratios fell over time, to 0.42 in 2012 (vs. 1996, 95% confidence interval [CI] = 0.32-0.54, P < 0.001). Adjusted incidence ratios for ESKD from scleroderma fell over time in both sexes, all age, race, and ethnicity categories except age < 20 years and Asian race, and in all regions of the United States. After initiating renal replacement therapy, patients with scleroderma had a greater likelihood of recovery of kidney function (hazards ratio [HR] = 2.67, 95% CI = 1.90-3.76, P < 0.001) and death (HR = 1.44, 95% CI = 1.34-1.54, P < 0.001) and a lower likelihood of transplantation (HR = 0.51, 95% CI = 0.44-0.59, P < 0.001) than demography-matched patients without scleroderma. CONCLUSION: The incidence of ESKD from scleroderma appears to have declined in the United States since 1996. ESKD from scleroderma is associated with an enhanced likelihood of recovery of kidney function and death, a reduced likelihood of transplantation, and similar outcomes after transplantation.

Epidemiology and Risk Factors for Early Mortality After Dialysis Initiation.

Confronted with the decision to initiate dialysis, patients and caregivers often seek information about how expected survival chances evolve, both initially and afterward, providing the patient survives beyond arbitrary periods of time. Large registry data, used to examine these issues, may be subject to early ascertainment bias, such as those accruing from nonregistration of with end-stage kidney disease who die shortly after dialysis initiation and inclusion of patients with acute kidney injury with slower than typical recovery rates. Despite these caveats, available studies have suggested that mortality hazards are much higher in the first 3 months of renal replacement therapy. Prominent modifiable associations of early mortality include late referral to nephrology services, initial dialysis with vascular catheters, and, most problematically, higher glomerular filtration rates at initiation of renal replacement therapy. Despite their imperfections, currently available information is relatively user-unfriendly and could be better leveraged to help patients and treatment teams make better decisions.

Renal Function Profile in White Kidney Donors: The First 4 Decades.

Previous studies reported the risk of ESRD after kidney donation, but not the renal outcomes that precede ESRD. Here, we estimated the risk of proteinuria, reduced GFR, and ESRD in 3956 white kidney donors, assessed the contribution of postdonation hypertension and diabetes to these outcomes, and developed a risk calculator. After a mean±SD follow-up of 16.6±11.9 years, 215 (6.1%) donors developed proteinuria. Men had a higher risk of proteinuria (hazard ratio [HR], 1.56; 95% confidence interval [95% CI], 1.18 to 2.05; P<0.001) as did those with higher body mass index (HR, 1.10; 95% CI, 1.06 to 1.13; P<0.001). In all, 1410 (36%) donors reached an eGFR<60 ml/min per 1.73 m(2), and 112 (2.8%) donors had either an eGFR<30 ml/min per 1.73 m(2) or ESRD (28 donors developed ESRD). An eGFR<30 ml/min per 1.73 m(2) or ESRD associated with older age (HR, 1.07; 95% CI, 1.05 to 1.09; P<0.001), higher body mass index (HR, 1.08; 95% CI, 1.04 to 1.13; P<0.001), and higher systolic BP (HR, 1.02; 95% CI, 1.00 to 1.04; P=0.01) at donation. Postdonation diabetes and hypertension associated with a fourfold higher risk of proteinuria and a >2-fold higher risk of ESRD. Models predicting proteinuria and reduced eGFR performed well (C-index 0.77-1.00). In conclusion, severe reduction in GFR and ESRD after kidney donation were uncommon and were highly associated with postdonation diabetes and hypertension. Furthermore, information available before donation may predict long-term renal outcomes in white living kidney donors.

The Brain in Kidney Disease (BRINK) Cohort Study: Design and Baseline Cognitive Function.

BACKGROUND: The Brain in Kidney Disease (BRINK) Study aims to identify mechanisms that contribute to increased risk for cognitive impairment in patients with chronic kidney disease (CKD). We describe the rationale, design, and methods of the study and report baseline recruitment and cognitive function results. STUDY DESIGN: Longitudinal observational cohort study of the epidemiology of cognitive impairment in CKD. The primary aim is to characterize the association between (1) baseline and incident stroke, white matter disease, estimated glomerular filtration rate (eGFR), inflammation, microalbuminuria, and dialysis initiation and (2) cognitive decline over 3 years in a CKD cohort with a mean eGFR<45 mL/min/1.73 m(2). SETTING & PARTICIPANTS: Community-dwelling participants 45 years or older recruited from 4 health systems into 2 groups: reduced eGFR, defined as eGFR<60 mL/min/1.73 m(2) (non-dialysis dependent), and control, defined as eGFR≥60 mL/min/1.73 m(2). PREDICTOR: eGFR group. OUTCOMES: Performance on cognitive function tests and structural brain magnetic resonance imaging. MEASUREMENTS: Sequential cognitive and physical function testing, serum and urine biomarker measurement, and brain magnetic resonance images over 3 years. RESULTS: Of 554 participants, mean age was 69.3 years; 333, 88, and 133 had eGFRs<45 (non-dialysis dependent, nontransplantation), 45 to <60, and ≥60 (controls) mL/min/1.73 m(2), respectively. Mean eGFR in reduced-eGFR participants was 34.3 mL/min/1.73 m(2). Baseline cognitive performance was significantly associated with eGFR in all domains except language. Participants with eGFRs<30 mL/min/1.73 m(2) performed significantly worse than those with eGFRs≥30 mL/min/1.73 m(2) on tests of memory, processing speed, and executive function. Participants with reduced eGFRs overall scored worst on the Immediate Brief Visual-Spatial Memory Test-Revised. LIMITATIONS: Healthy cohort bias, competing risk for death versus cognitive decline. CONCLUSIONS: Cognitive function was significantly worse in participants with eGFRs<30 mL/min/1.73 m(2). Future BRINK analyses will measure risk factors for cognitive decline using the longitudinal data.

ESRD due to Multiple Myeloma in the United States, 2001-2010.

Although management of multiple myeloma has changed substantially in the last decade, it is unknown whether the burden of ESRD due to multiple myeloma has changed, or whether survival of patients with multiple myeloma on RRT has improved. Regarding ESRD due to multiple myeloma necessitating RRT in the United States, we evaluated temporal trends between 2001 and 2010 for demography-adjusted incidence ratios, relative to rates in 2001-2002, and mortality hazards from RRT initiation, relative to hazards in 2001-2002. In this retrospective cohort study, we used the US Renal Data System database (n=1,069,343), 2001-2010, to identify patients with ESRD due to multiple myeloma treated with RRT (n=12,703). Demography-adjusted incidence ratios of ESRD from multiple myeloma decreased between 2001-2002 and 2009-2010 in the overall population (demography-adjusted incidence ratio 0.82; 95% confidence interval, 0.79 to 0.86) and in most demographic subgroups examined. Mortality rates were 86.7, 41.4, and 34.4 per 100 person-years in the first 3 years of RRT, respectively, compared with 32.3, 20.6, and 21.3 in matched controls without multiple myeloma. Unadjusted mortality hazards ratios declined monotonically after 2004 to a value of 0.72; 95% confidence interval, 0.67 to 0.77 in 2009-2010, and declines between 2001-2002 and 2008-2009 were observed (P<0.05) in most demographic subgroups examined. Findings were similar when adjustment was made for demographic characteristics, comorbidity markers, and laboratory test values. These data suggest the incidence of RRT from multiple myeloma in the United States has decreased in the last decade, and clinically meaningful increases in survival have occurred for these patients.

United States Renal Data System public health surveillance of chronic kidney disease and end-stage renal disease.

The United States Renal Data System (USRDS) began in 1989 through US Congressional authorization under National Institutes of Health competitive contracting. Its history includes five contract periods, two of 5 years, two of 7.5 years, and the fifth, awarded in February 2014, of 5 years. Over these 25 years, USRDS reporting transitioned from basic incidence and prevalence of end-stage renal disease (ESRD), modalities, and overall survival, as well as focused special studies on dialysis, in the first two contract periods to a comprehensive assessment of aspects of care that affect morbidity and mortality in the second two periods. Beginning in 1999, the Minneapolis Medical Research Foundation investigative team transformed the USRDS into a total care reporting system including disease severity, hospitalizations, pediatric populations, prescription drug use, and chronic kidney disease and the transition to ESRD. Areas of focus included issues related to death rates in the first 4 months of treatment, sudden cardiac death, ischemic and valvular heart disease, congestive heart failure, atrial fibrillation, and infectious complications (particularly related to dialysis catheters) in hemodialysis and peritoneal dialysis patients; the burden of congestive heart failure and infectious complications in pediatric dialysis and transplant populations; and morbidity and access to care. The team documented a plateau and decline in incidence rates, a 28% decline in death rates since 2001, and changes under the 2011 Prospective Payment System with expanded bundled payments for each dialysis treatment. The team reported on Bayesian methods to calculate mortality ratios, which reduce the challenges of traditional methods, and introduced objectives under the Health People 2010 and 2020 national health care goals for kidney disease.

Randomized controlled trials 2: Analysis.

When analyzing the results of a trial the primary outcome variable must be kept in clear focus. In the analysis plan consideration must be given to comparing the characteristics of the subjects, taking account of differences in these characteristics, intention to treat analysis, interim analyses and stopping rules, mortality comparisons, composite outcomes, research design including run-in periods, factorial, stratified, and crossover designs, number needed to treat, power issues, multivariate modeling, and hypothesis-generating analyses.

Randomized controlled trials 7: Analysis and interpretation of quality-of-life scores.

Quality-of-life (QoL) outcomes are important elements of randomized controlled trials. The instruments for measurement of QoL vary but usually multiple comparisons are possible, a concern that can be offset by prespecifying the outcomes of interest. Missing data may threaten the validity of QoL assessments in trials. Therefore familiarity with the strategies used to account for missing data is necessary. Measures that incorporate both survival and QoL are helpful for treatment decisions. The definition of minimal clinically important differences in QoL scores is important and often derived using inadequate methods.

End-stage renal disease from hemolytic uremic syndrome in the United States, 1995-2010.

Management of hemolytic uremic syndrome (HUS) has evolved rapidly, and optimal treatment strategies are controversial. However, it is unknown whether the burden of end-stage renal disease (ESRD) from HUS has changed, and outcomes on dialysis in the United States are not well described. We retrospectively examined data for patients initiating maintenance renal replacement therapy (RRT) (n = 1,557,117), 1995-2010, to define standardized incidence ratios (SIRs) and outcomes of ESRD from HUS) (n = 2241). Overall ESRD rates from HUS in 2001-2002 were 0.5 cases/million per year and were higher for patients characterized by age 40-64 years (0.6), ≥65 years (0.7), female sex (0.6), and non-Hispanic African American race (0.7). Standardized incidence ratios remained unchanged (P ≥ 0.05) between 2001-2002 and 2009-2010 in the overall population. Compared with patients with ESRD from other causes, patients with HUS were more likely to be younger, female, white, and non-Hispanic. Over 5.4 years of follow-up, HUS patients differed from matched controls with ESRD from other causes by lower rates of death (8.3 per 100 person-years in cases vs. 10.4 in controls, P < 0.001), listing for renal transplant (7.6 vs. 8.6 per 100 person-years, P = 0.04), and undergoing transplant (6.9 vs. 9 per 100 person-years, P < 0.001). The incidence of ESRD from HUS appears not to have risen substantially in the last decade. However, given that HUS subtypes could not be determined in this study, these findings should be interpreted with caution.

End-stage renal disease attributed to acute tubular necrosis in the United States, 2001-2010.

BACKGROUND/AIMS: Though end-stage renal disease (ESRD) is increasingly attributed to acute tubular necrosis (ATN), contemporary trends in the rates of incidence and recovery of renal function are poorly defined. Hence, we set out to describe the clinical epidemiology of ESRD due to ATN between 2001 and 2010. METHODS: We examined United States Renal Data System data (n = 1,070,490) for 2001 through 2010 to calculate the incidence rates and rates of renal recovery and death for patients with ESRD due to ATN treated with renal replacement therapy (RRT, n = 27,603). RESULTS: Standardized incidence ratios increased between 2001-2002 and 2009-2010 in the overall population (ratio 2.14), having risen in all demographic subgroups examined. Recovery of renal function was more likely in patients with ATN than in matched controls (cumulative incidence 23% vs. 2% at 12 weeks, 34% vs. 4% at 1 year), as was death (cumulative incidence 38% vs. 27% at 1 year). Hazards ratios for renal recovery increased stepwise with year of RRT inception to 1.34 (95% confidence interval 1.24-1.45) for 2009-2010 (vs. 2001-2002). In contrast, hazards ratios for death declined stepwise to 0.83 (0.79-0.87) in 2009-2010. CONCLUSION: While the incidence of ESRD attributed to ATN has increased, prospects of renal recovery and survival have also increased. Despite substantial mortality risk on RRT, renal recovery is not a rare occurrence.