Segmental kidney volumes measured by dynamic contrast-enhanced magnetic resonance imaging and their association with CKD in older people.

Background: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a potentially powerful tool for analysis of kidney structure and function. The ability to measure functional and hypofunctional tissues could provide important information in groups at risk for chronic kidney disease (CKD), such as the elderly.

Study Design: Observational study with a cross-sectional design.

Decline in estimated glomerular filtration rate and subsequent risk of end-stage renal disease and mortality.

Importance: The established chronic kidney disease (CKD) progression end point of end-stage renal disease (ESRD) or a doubling of serum creatinine concentration (corresponding to a change in estimated glomerular filtration rate [GFR] of −57% or greater) is a late event.

Objective: To characterize the association of decline in estimated GFR with subsequent progression to ESRD with implications for using lesser declines in estimated GFR as potential alternative end points for CKD progression. Because most people with CKD die before reaching ESRD, mortality risk also was investigated.

Early change in proteinuria as a surrogate end point for kidney disease progression: an individual patient meta-analysis.

Background: It is controversial whether proteinuria is a valid surrogate end point for randomized trials in chronic kidney disease.

Study Design: Meta-analysis of individual patient-level data.

Setting & Population: Individual patient data for 9,008 patients from 32 randomized trials evaluating 5 intervention types.

Performance of creatinine-based GFR estimating equations in solid-organ transplant recipients.

Background: Accurate assessment of kidney function is important for the management of solid-organ transplant recipients. In other clinical populations, glomerular filtration rate (GFR) most commonly is estimated using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine or the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation. The accuracy of these equations compared with other GFR estimating equations in transplant recipients has not been carefully studied.

KDOQI US commentary on the 2012 KDIGO clinical practice guideline for the evaluation and management of CKD.

The National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guideline for evaluation, classification, and stratification of chronic kidney disease (CKD) was published in 2002. The KDOQI guideline was well accepted by the medical and public health communities, but concerns and criticisms arose as new evidence became available since the publication of the original guidelines. KDIGO (Kidney Disease: Improving Global Outcomes) recently published an updated guideline to clarify the definition and classification of CKD and to update recommendations for the evaluation and management of individuals with CKD based on new evidence published since 2002.

GFR estimation: from physiology to public health.

Estimating glomerular filtration rate (GFR) is essential for clinical practice, research, and public health. Appropriate interpretation of estimated GFR (eGFR) requires understanding the principles of physiology, laboratory medicine, epidemiology, and biostatistics used in the development and validation of GFR estimating equations. Equations developed in diverse populations are less biased at higher GFRs than equations developed in chronic kidney disease (CKD) populations and are more appropriate for general use.

Glomerular filtration rate estimation using cystatin C alone or combined with creatinine as a confirmatory test.

Background: Glomerular filtration rate (GFR) estimating equations using the combination of creatinine and cystatin C (eGFRcr-cys) are more accurate than equations using either alone (eGFRcr or eGFRcys). New guidelines suggest measuring cystatin C as a confirmatory test when eGFRcr may be inaccurate, but do not specify demographic or clinical conditions in which eGFRcys or eGFRcr-cys are more accurate than eGFRcr nor which estimate to use in such circumstances.

Methods: We compared the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in 1119 subjects in the CKD-EPI cystatin C external validation dataset.

Potential effects of reclassifying CKD as a coronary heart disease risk equivalent in the US population.

Background: Persons with chronic kidney disease (CKD) are at high risk for cardiovascular disease events, but are not classified as such in current US cholesterol treatment guidelines. We examined potential effects of modified guidelines in which CKD was considered a "coronary heart disease (CHD) risk equivalent" for risk stratification.

Study Design: Nationally representative cross-sectional study.

Cystatin C- and creatinine-based estimated glomerular filtration rate, vascular disease, and mortality in persons with diabetes in the U.S.

OBJECTIVE Serum cystatin C is an alternative to serum creatinine for estimating glomerular filtration rate (GFR), since cystatin C is less influenced by age and muscle mass. Among persons with diabetes, we compared the performance of GFR estimated using cystatin C (eGFRcys) with that using creatinine (eGFRcr) for the identification of reduced kidney function and its association with diabetes complications. RESEARCH DESIGN AND METHODS We analyzed data from adult participants from the 1999-2002 National Health and Nutrition Examination Survey with available cystatin C (N = 4,457).

Estimated GFR decline as a surrogate end point for kidney failure: a post hoc analysis from the Reduction of End Points in Non-Insulin-Dependent Diabetes With the Angiotensin II Antagonist Losartan (RENAAL) study and Irbesartan Diabetic Nephropathy Trial (IDNT).

Background: A doubling of serum creatinine value, corresponding to a 57% decline in estimated glomerular filtration rate (eGFR), is used frequently as a component of a composite kidney end point in clinical trials in type 2 diabetes. The aim of this study was to determine whether alternative end points defined by smaller declines in eGFR would improve the statistical power of these clinical trials.

Study Design: Post hoc analyses of 2 multinational randomized controlled trials (Reduction of End Points in Non-Insulin-Dependent Diabetes With the Angiotensin II Antagonist Losartan [RENAAL] and Irbesartan Diabetic Nephropathy Trial [IDNT]) that assessed the treatment effect of the angiotensin receptor blockers (ARBs) losartan and irbesartan.

Estimation of GFR in South Asians: a study from the general population in Pakistan.

Background: South Asians are at high risk for chronic kidney disease. However, unlike those in the United States and United Kingdom, laboratories in South Asian countries do not routinely report estimated glomerular filtration rate (eGFR) when serum creatinine is measured. The objectives of the study were to: (1) evaluate the performance of existing GFR estimating equations in South Asians, and (2) modify the existing equations or develop a new equation for use in this population.

Cystatin C versus creatinine in determining risk based on kidney function.

Background: Adding the measurement of cystatin C to that of serum creatinine to determine the estimated glomerular filtration rate (eGFR) improves accuracy, but the effect on detection, staging, and risk classification of chronic kidney disease across diverse populations has not been determined.

Methods: We performed a meta-analysis of 11 general-population studies (with 90,750 participants) and 5 studies of cohorts with chronic kidney disease (2960 participants) for whom standardized measurements of serum creatinine and cystatin C were available. We compared the association of the eGFR, as calculated by the measurement of creatinine or cystatin C alone or in combination with creatinine, with the rates of death (13,202 deaths in 15 cohorts), death from cardiovascular causes (3471 in 12 cohorts), and end-stage renal disease (1654 cases in 7 cohorts) and assessed improvement in reclassification with the use of cystatin C.

Use of glomerular filtration rate estimating equations for drug dosing in HIV-positive patients.

Background: Current HIV treatment guidelines recommend using the Cockcroft-Gault equation for drug dosing adjustments. The use of newer glomerular filtration rate (GFR) estimating equations for drug dosing and the appropriateness of physician antiretroviral dosing based on estimated kidney function have not been studied in an HIV-positive population.

Methods: We evaluated concordance between measured and estimated GFR for the assignment of kidney function categories designated by the US Food and Drug Administration (FDA) Guidance for industry for pharmacokinetic studies, and appropriateness of physician antiretroviral drug dosing for level of kidney function in 200 HIV-positive patients on stable antiretroviral therapy.

Influence of urine creatinine concentrations on the relation of albumin-creatinine ratio with cardiovascular disease events: the Multi-Ethnic Study of Atherosclerosis (MESA).

Background: Higher urine albumin-creatinine ratio (ACR) is associated with cardiovascular disease (CVD) events, an association that is stronger than that between spot urine albumin on its own and CVD. Urine creatinine excretion is correlated with muscle mass, and low muscle mass also is associated with CVD. Whether low urine creatinine concentration in the denominator of the ACR contributes to the association of ACR with CVD is uncertain.

Cardiovascular risk factor burden, treatment, and control among adults with chronic kidney disease in the United States.

Background: Cardiovascular disease is a major concern in persons with chronic kidney disease (CKD). We assessed the current burden of cardiovascular risk factors and differences in risk factor treatment and control in the general US adult population by CKD status.

Methods: A cross-sectional study of 10,741 adults aged 20+ years from the 2007-2010 National Health and Nutrition Examination Survey was performed.

The association of chronic kidney disease complications by albuminuria and glomerular filtration rate: a cross-sectional analysis.

Background: Albuminuria is strongly associated with future risk for cardiovascular and kidney outcomes, and has been proposed to be included in the classification of chronic kidney disease (CKD) along with glomerular filtration rate (GFR). Few data are available on whether albuminuria is associated with concurrent complications of CKD.

Methods: A cross-sectional analysis of 1,665 participants screened for the Modification of Diet in Renal Disease (MDRD) study was performed to examine the association between albuminuria (determined using urine albumin-creatinine ratio (ACR)) and measured GFR (determined using urinary clearance of iothalamate) with anemia, acidosis, hyperphosphatemia, and hypertension.

Trends in the prevalence of reduced GFR in the United States: a comparison of creatinine- and cystatin C-based estimates.

Background: The US prevalence of reduced estimated glomerular filtration rate (eGFR) based on serum creatinine level increased during the decade ending in 2002. National Health and Nutrition Examination Survey (NHANES) cystatin C measurements recently were calibrated to the international standard, allowing for an independent test of the trend in prevalence of reduced eGFR using cystatin C level.

Study Design: Cross-sectional surveys performed during 2 periods.

Risk prediction models for patients with chronic kidney disease: a systematic review.

Background: Patients with chronic kidney disease (CKD) are at increased risk for kidney failure, cardiovascular events, and all-cause mortality. Accurate models are needed to predict the individual risk for these outcomes.

Purpose: To systematically review risk prediction models for kidney failure, cardiovascular events, and death in patients with CKD.

Novel filtration markers as predictors of all-cause and cardiovascular mortality in US adults.

Background: New filtration markers, including β-trace protein (BTP) and β₂-microglobulin (B2M), may, similar to cystatin C, enable a stronger prediction of mortality compared to serum creatinine-based estimated glomerular filtration rate (eGFRcr). We sought to evaluate these mortality associations in a representative sample of US adults.

Study Design: Prospective cohort study.

Within-person variability in kidney measures.

Background: Our objective was to quantify short-term total within-person variability in standard and nontraditional kidney measures using national data.

Study Design: Repeated examination study of serum and urine kidney measures.

Setting & Participants: Participants 18 years or older in the Third National Health and Nutrition Examination Survey (NHANES III) who had repeated blood and urine samples collected during visits occurring approximately 18 days apart.