Limitations of estimating glomerular filtration rate from serum creatinine in the general population

Strategies to prevent, diagnose and treat kidney disease related to systemic arterial hypertension: a narrative review from the Mexican Group of Experts on Arterial Hypertension

This narrative review highlights strategies proposed by the Mexican Group of Experts on Arterial Hypertension endorsed to prevent, diagnose, and treat chronic kidney disease (CKD) related to systemic arterial hypertension (SAH). Given the growing prevalence of CKD in Mexico and Latin America caused by SAH, there is a need for context-specific approaches to address the effects of SAH, given the diverse population and unique challenges faced by the region. This narrative review provides clinical strategies for healthcare providers on preventing, diagnosing, and treating kidney disease related to SAH, focusing on primary prevention, early detection, evidence-based diagnostic approaches, and selecting pharmacological treatments. Key-strategies are focused on six fundamental areas: 1) Strategies to mitigate kidney disease in SAH, 2) early detection of CKD in SAH, 3) diagnosis and monitoring of SAH, 4) blood pressure targets in patients living with CKD, 5) hypertensive treatment in patients with CKD and 6) diuretics and Non-Steroidal Mineralocorticoid Receptor Inhibitors in Patients with CKD. This review aims to provide relevant strategies for the Mexican and Latin American clinical context, highlight the importance of a multidisciplinary approach to managing SAH, and the role of community-based programs in improving the quality of life for affected individuals. This position paper seeks to contribute to reducing the burden of SAH-related CKD and its complications in Mexico and Latin America.

Chronic kidney disease unawareness and determinants using 1999-2014 National Health and Nutrition Examination Survey Data

BACKGROUND

Although chronic kidney disease (CKD) affects 15% of the United States (US) population, <10% of the US CKD population is aware of their disease. This is significant as untreated CKD can progress to end-stage renal disease which would require dialysis or transplantation. This study aimed to provide updated information regarding US CKD unawareness.

METHODS

Data from the 1999-2014 National Health and Nutrition Examination Survey (NHANES) were used (n = 38 474); response rate > 70%. CKD self-report and lab-confirmed CKD were used to assess CKD unawareness. Adjusted logistic regression models examined association between unawareness and patient characteristics.

RESULTS

In individuals with lab-confirmed CKD (n = 7137, 14.3%), 91.5% answered 'no' to self-report question; in those without CKD, 1.1% answered 'yes' to self-report question. In those with lab-confirmed CKD, in the adjusted models, increased age [odds ratio (ORs), 1.03 (95%CI, 1.02-1.04)] and female sex [OR, 1.37 (95%CI, 1.08-1.72)] were statistically significantly associated with greater odds of being unaware of CKD.

CONCLUSION

These findings demonstrated high unawareness of disease status as there was a discrepancy between respondents' self-reported CKD diagnosis and lab-confirmed CKD. Older individuals and women may be more unaware of their CKD; these groups should be queried about reasons for increased unawareness.

Renal length z-score for the detection of dysfunction in children with solitary functioning kidney

AIM

To evaluate whether renal length z-scores predict renal dysfunction in children with a solitary functioning kidney (SFK).

METHODS

In a single-centre retrospective cohort of children with SFK, we correlated body mass index z-scores, extracellular volume and lean body mass to renal length z-scores. We grouped these z-scores to other markers of renal dysfunction (proteinuria, hypertension, extracellular volume and abnormal estimated glomerular function rate [eGFR]) and analysed renal length z-score with multivariate analysis, receiver-operated characteristics (ROC) plots and Youden's index to determine an appropriate cut-off.

RESULTS

111 children had a median follow-up 5.08 years, eGFR 80.8 mL/min/1.73 m² , and age at last follow-up 7.4 (3.8-13.4 years). The median renal length z-scores of those without any renal dysfunction (n = 37, 25.1%) were greater (+3.66, interquartile range 3.02-4.47) than those with renal dysfunction (median 3.11, interquartile range 1.76-4.11, P = .0107, Mann-Whitney test). Using a cut-off of z-score of >+1.911, the odds ratio for having no renal dysfunction was 0.07 (95% CI 0.002-0.459, P = .0010). However, accuracy of the renal length z-score was poor (ROC curve 0.6488).

CONCLUSION

In this cohort of children with SKF, using the renal length z-score as a biomarker of renal dysfunction at 7 years of age is not recommended.

Clinician perspectives on inpatient cystatin C utilization: A qualitative case study at Mayo Clinic

Introduction

Serum creatinine (SCr) testing has been the mainstay of kidney function assessment for decades despite known limitations. Cystatin C (CysC) is an alternative biomarker that is generally less affected than SCr by pertinent non-renal factors in hospitalized patients, such as muscle mass. Despite its potential advantages, the adoption of CysC for inpatient care is not widespread. At one hospital with CysC testing, we demonstrated a significant rise in non-protocolized use over the last decade. This study uses qualitative methods to provide the first report of how clinicians understand, approach, and apply CysC testing in inpatient care.

Methods

Fifteen clinicians from various disciplines were interviewed about their experience with inpatient CysC testing. The semi-structured interviews were audio-recorded, transcribed verbatim, and analyzed thematically using a phenomenological approach.

Results

Knowledge and confidence with CysC varied greatly. Clinicians reported first learning about the test from colleagues on consulting services or multidisciplinary teams. The majority believed CysC to provide a more accurate measure of kidney function than SCr. Common scenarios for CysC ordering included medication dosing, evaluation of acute kidney injury, and a thorough evaluation of kidney function in patients with risk factors for an altered SCr. Facilitators for ordering CysC included the availability of rapid results turnaround and the automated calculation of glomerular filtration rate based on the biomarker. Barriers to use included a lack of education about CysC, and the absence of an institutional protocol for use.

Discussion

Clinicians at our site decided independent of institutional guidance whether and when CysC added value to patient care. While the majority of study participants indicated advantages to rapid turnaround CysC testing, its use depended not just on the features of the specific case but on clinician familiarity and personal preference. Findings from this research can guide the implementation and expansion of CysC testing.

Prescribing medicines to older people-How to consider the impact of ageing on human organ and body functions

Ageing is associated with several changes in human organs, which result in altered medication pharmacokinetics and pharmacodynamics. Ageing is also associated with changes in human body functions, such as impaired vision, hearing, swallowing, motor and cognitive functions, which can affect the adequate intake and administration of drugs. As a consequence, older people, and especially patients older than 75 years, are the main users of many drugs and they frequently use 5 drugs or more long-term (i.e. polypharmacy). All this increases the complexity of adequate drug intake, administration and adherence. However, there is a lack of evidence on the considerations that should be taken into account to ensure appropriate drug prescribing to older people. This review article summarizes the most clinically relevant changes in human organ and body functions and the consequential changes in pharmacokinetics and pharmacodynamics in older people, along with possible dosing consequences or alternatives for drugs frequently prescribed to this patient population. Recommendations are given on how ageing could be considered in clinical drug development, drug authorization and appropriate prescribing.

Does Creatine Supplementation Affect Renal Function in Patients with Peripheral Artery Disease? A Randomized, Double Blind, Placebo-controlled, Clinical Trial

BACKGROUND

Case studies and reviews have shown that creatine supplementation can affect kidney function. The objective of this study is to verify the effects of 8 weeks of creatine supplementation on renal function (creatinine clearance: primary outcome) in patients with symptomatic peripheral arterial disease.

METHODS

Twenty-nine patients, of both genders, were randomized (1:1) in a double-blind manner for administration of Placebo (PLA; n = 15) or creatine monohydrate (Cr; n = 14). The supplementation protocol consisted of 20 g/day for 1 week divided into 4 equal doses (loading phase), followed by single daily doses of 5 g in the subsequent 7 weeks (maintenance phase). Before and after the supplementation period, markers of renal function, serum creatinine, creatinine excretion rate, and creatinine clearance were evaluated. The Generalized Estimation Equation Model was used for comparison between groups. The level of significance was P < 0.05.

RESULTS

No significant differences were found between groups before and after the intervention for serum creatinine (Cr: pre 1.00 ± 0.15 mL/dL vs. post 1.07 ± 0.16 mL/dL; PLA: pre 1.30 ± 0.53 mL/dL vs. post 1.36 ± 0.47 mL/dL, P = 0.590), creatinine excretion rate (Cr: pre 81.73 ± 43.80 mg/dL vs. post 102.92 ± 59.57 mg/dL; PLA: pre 74.37 ± 38.90 mg/dL vs. post 86.22 ± 39.94 mg/dL, P = 0.560), or creatinine clearance (Cr; pre 108 ± 59 mL/min/1.73 m² vs. post 117 ± 52 mL/min/1.73 m²; PLA: pre 88 ± 49 mL/min/1.73 m² vs. post 82 ± 47 mL/min/1.73 m², P = 0.366).

CONCLUSIONS

Eight weeks of creatine supplementation is safe and does not compromise the renal function of patients with peripheral arterial disease.

Performance of glomerular filtration rate estimating equations in a community-based sample of Blacks and Whites: the multiethnic study of atherosclerosis

Background

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations are recommended for glomerular filtration rate (GFR) estimation in the general population. They have not been evaluated in community-based populations, including Blacks at higher levels of GFR, but are commonly applied in such populations.

Methods

In an ancillary study of Multi-Ethnic Study of Atherosclerosis conducted at one site, we evaluated the performance of the CKD-EPI equations for creatinine (eGFRcr), cystatin C (eGFRcys) or the combination (eGFRcr-cys) compared with GFR measured as plasma clearance of iohexol.

Results

Among 294 participants, the mean age was 71 (SD 9) years, 47% were Black, 48% were women and the mean measured GFR (mGFR) was 72.6 (SD 18.8) mL/min/1.73 m2. The CKD-EPI equations overestimated mGFR with a larger median bias for eGFRcr and eGFRcr-cys than eGFRcys [-8.3 (95% confidence interval -9.7, -6.5), -7.8 (-9.2, -6.2) and -3.7 (-5.0, -1.8) mL/min/1.73 m2, respectively], with smaller bias for those with lower compared with higher eGFR and by race compared with sex.

Conclusion

The small differential bias of the CKD-EPI equation between races suggests that they can be used in Blacks as well as Whites in older community-based adults. The large differential bias in women versus men in all equations is in contrast to other studies and is unexplained. Further studies are required in multiracial and multiethnic community-based cohorts, taking into account differences in GFR measurement methods.

Salivary microbial analysis of Chinese patients with immunoglobulin A nephropathy

Microbiota plays an important role in immunoglobulin A (IgA) nephropathy (IgAN); however, the pathogenesis, early diagnosis, and treatment of IgAN remain unclear. The aim of the present study was to develop a preliminary model based on saliva‑specific microbes and clinical indicators to facilitate the early diagnosis of IgAN and obtain insights into its treatment. The microbial profile of the saliva of 28 IgAN patients and 25 healthy control subjects was investigated using high‑throughput sequencing and bioinformatics analyses of the V4 region in microbial 16S rRNA genes. IgAN patients and healthy subjects did not differ significantly in α‑diversity indices (Chao1 and Shannon index) or phylum composition. At the genus level, however, Granulicatella was significantly less abundant in healthy individuals than in IgAN patients, while Prevotella and Veillonella were significantly more abundant in the healthy subjects than in IgAN patients (P<0.05 and P<0.01, respectively). Correlation analysis between biochemical indicators and operational taxonomic units (OTUs) revealed that the glomerular filtration rate was positively correlated with OTU86 and OTU287 at P<0.05, positively correlated with OTU165 at P<0.001, and negatively correlated with OTU455 at P<0.05. The serum creatinine index was negatively correlated with OTU287 at P<0.05 and negatively correlated with OTU165 at P<0.001. The pathological changes were positively correlated with OTU255 at P<0.05, OTU200 at P<0.01, and OTU455 and OTU75 at P<0.001, and negatively correlated with OTU86, OTU287, and OTU788 at P<0.05 and with OTU165 at P<0.01. The differences between Chinese IgAN patients and healthy subjects in terms of OTUs and biochemical indicators were analyzed and a mathematical model to facilitate the clinical diagnosis of IgAN was established.

Serum cystatin C, impaired kidney function, and geriatric depressive symptoms among older people living in a rural area: a population-based study

BACKGROUND

The relationship between kidney function and depressive symptoms among elderly people has been rarely investigated in settings of the general population. The aim of our study was to examine the association of serum cystatin C (cysC) and impaired kidney function with geriatric depressive symptoms among older people living in a rural community in China.

METHODS

This population-based cohort study included 1440 individuals (age ≥ 60 years) who were recruited for the Confucius Hometown Aging Project in 2010-2011; of the 1124 persons who were free of depressive symptoms, 669 (59.5%) were re-examined in 2014-2016. At baseline, data on demographics, lifestyle factors, health conditions, and medical history were collected through interviews, clinical examinations, and laboratory tests. We defined impaired kidney function as the cystatin C-based estimated glomerular filtration rate (eGFR_cysC) < 60 ml/min/1.73 m², and depressive symptoms as a score ≥ 5 on the 15-item Geriatric Depression Scale. Data were analyzed using multiple logistic and Cox proportional-hazards models.

RESULTS

Of the 1440 participants, 316 (21.9%) were defined to have geriatric depressive symptoms at baseline. Serum cysC levels of 1.01-1.25 and > 1.25 mg/L (vs. ≤1.00 mg/L) were associated with a multiple-adjusted odds ratio (OR) of 1.41 (95% CI 1.01-1.97) and 3.20 (2.32-4.41), respectively, for having geriatric depressive symptoms (P_trend < 0.001). Of the 669 people who were free of depressive symptoms at baseline, 157 had incident depressive symptoms at the follow-up examination. The multiple-adjusted hazard ratio (HR) for incident depressive symptoms were 2.16 (95% CI 1.43-3.27) for serum cysC > 1.25 mg/L (vs. < 1.00 mg/L). Impaired kidney function was cross-sectionally (multiple-adjusted OR = 2.95; 95% CI 2.22-3.92) and longitudinally (multiple-adjusted HR 1.54; 95% CI 1.03-2.30) associated with an increased risk of geriatric depressive symptoms.

CONCLUSION

Elevated serum cysC levels and impaired kidney function are associated with an increased risk of geriatric depressive symptoms among Chinese older people living in a rural community.

Comparison of equations for estimating glomerular filtration rate in screening for chronic kidney disease in asymptomatic black Africans: a cross sectional study

BACKGROUND

Several equations have been developed to estimate glomerular filtration rate (eGFR). The common equations used were derived from populations predominantly comprised of Caucasians with chronic kidney disease (CKD). Some of the equations provide a correction factor for African-Americans due to their relatively increased muscle mass and this has been extrapolated to black Africans. Studies carried out in Africa in patients with CKD suggest that using this correction factor for the black African race may not be appropriate. However, these studies were not carried out in healthy individuals and as such the extrapolation of the findings to an asymptomatic black African population is questionable. We sought to compare the proportion of asymptomatic black Africans reported as having reduced eGFR using various eGFR equations. We further compared the association between known risk factors for CKD with eGFR determined using the different equations.

METHODS

We used participant and laboratory data collected as part of a global reference interval study conducted by the Committee of Reference Intervals and Decision Limits (C-RIDL) under the International Federation of Clinical Chemistry (IFCC). Serum creatinine values were used to calculate eGFR using the Cockcroft-Gault (CG), re-expressed 4 variable modified diet in renal disease (4v-MDRD), full age spectrum (FAS) and chronic kidney disease epidemiology collaboration equations (CKD-EPI). CKD classification based on eGFR was determined for every participant.

RESULTS

A total of 533 participants were included comprising 273 (51.2%) females. The 4v-MDRD equation without correction for race classified the least number of participants (61.7%) as having an eGFR equivalent to CKD stage G1 compared to 93.6% for CKD-EPI with correction for race. Only age had a statistically significant linear association with eGFR across all equations after performing multiple regression analysis. The multiple correlation coefficients for CKD risk factors were higher for CKD-EPI determined eGFRs.

CONCLUSIONS

This study found that eGFR determined using CKD-EPI equations better correlated with a prediction model that included risk factors for CKD and classified fewer asymptomatic black Africans as having a reduced eGFR compared to 4v-MDRD, FAS and CG corrected for body surface area.

Screening for chronic kidney disease of uncertain aetiology in Sri Lanka: usability of surrogate biomarkers over dipstick proteinuria

Background

The use of dipstick proteinuria to screen Chronic Kidney Disease of uncertain aetiology (CKDu) in Sri Lanka is a recently debated matter of dispute. The aim of this study was to assess the suitability of biomarkers: serum creatinine, cystatin C and urine albumin to creatinine ratio (ACR) for screening CKDu in Sri Lanka.

Methods

Forty-four male CKDu patients and 49 healthy males from a CKDu-endemic region were selected. Meanwhile, 25 healthy males from a non-endemic region were selected as an absolute control. The diagnostic accuracy of each marker was compared using the above three study groups.

Results

In receiver operating characteristics (ROC) plots for creatinine, cystatin C and ACR, values of area under the curve (AUC) were 0.926, 0.920 and 0.737 respectively when CKDu was compared to non-endemic control. When CKDu was compared to endemic control, AUCs of above three analytes were distinctly lower as 0.718, 0.808 and 0.678 respectively. Cystatin C exhibited the highest sensitivity for CKDu when analyzed against both control groups where respective sensitivities were 0.75 against endemic control and 0.89 against non-endemic control. ROC-optimal cutoff limits of creatinine, cystatin C and ACR in CKDu vs non-endemic control were 89.0 μmol/L, 1.01 mg/L and 6.06 mg/g-Cr respectively, whereas in CKDu vs endemic control the respective values were 111.5 μmol/L, 1.22 mg/L and 12.66 mg/g-Cr.

Conclusions

Amongst the three biomarkers evaluated in this study, our data suggest that Cystatin C is the most accurate functional marker in detecting CKDu in endemic regions, yet the high cost hinders its usability on general population. Creatinine is favorable over dipstick proteinuria owing to its apparent accuracy and cost efficiency, while having the ability to complement the kidney damage marker (ACR) in screening. ACR may not be favorable as a standalone screening marker in place of dipstick proteinuria due to its significant decline in sensitivity against the CKDu-endemic population. However, creatinine and ACR in a complementary manner could overcome current shortcomings of dipstick proteinuria and such a dual marker tool could be commodious in screening CKDu-type tubulointerstital diseases. Furthermore, use of ACR may also increase the ability to clinically discriminate CKDu from other glomerular nephropathies.

Potential Role of Serum and Urinary Biomarkers in Diagnosis and Prognosis of Diabetic Nephropathy

PURPOSE OF REVIEW

Diabetic nephropathy (DN) is a progressive kidney disease caused by alterations in kidney architecture and function, and constitutes one of the leading causes of end-stage renal disease (ESRD). The purpose of this review is to summarize the state of the art of the DN-biomarker field with a focus on the new strategies that enhance the sensitivity of biomarkers to predict patients who will develop DN or are at risk of progressing to ESRD.

OBJECTIVE

In this review, we provide a description of the pathophysiology of DN and propose a panel of novel putative biomarkers associated with DN pathophysiology that have been increasingly investigated for diagnosis, to predict disease progression or to provide efficient personal treatment.

METHODS

We performed a review of the literature with PubMed and Google Scholar to collect baseline data about the pathophysiology of DN and biomarkers associated. We focused our research on new and emerging biomarkers of DN.

KEY FINDINGS

In this review, we summarized the critical signaling pathways and biological processes involved in DN and highlighted the pathogenic mediators of this disease. We next proposed a large review of the major advances that have been made in identifying new biomarkers which are more sensitive and reliable compared with currently used biomarkers. This includes information about emergent biomarkers such as functional noncoding RNAs, microRNAs, long noncoding RNAs, exosomes, and microparticles.

LIMITATIONS

Despite intensive strategies and constant investigation, no current single treatment has been able to reverse or at least mitigate the progression of DN, or reduce the morbidity and mortality associated with this disease. Major difficulties probably come from the renal disease being heterogeneous among the patients.

IMPLICATIONS

Expanding the proteomics screening, including oxidative stress and inflammatory markers, along with metabolomics approaches may further improve the prognostic value and help in identifying the patients with diabetes who are at high risk of developing kidney diseases.

Proceedings From the Symposium on Kidney Disease in Older People: Royal Society of Medicine, London, January 19, 2017

People are living longer. On the whole, they have healthier lives and many of the problems previously seen at a younger age now appear in their later years. Kidneys, like other organs, age, and kidney disease in the aged is a prime example. In the United Kingdom, as in other developed countries, the prevalence of end stage kidney disease is highest in the 70- to 79-year-old age group. There are many older people who require renal replacement and are now considered for dialysis. While older patients with end-stage renal disease invariably aspire for a better quality of life, this needs a specialized approach and management. In January 2017, the Royal Society of Medicine held a seminar in London on "Kidney Disease in Older People" with presentations from a multidisciplinary body of experts speaking on various aspects of kidney problems in this age group and its management. The objectives were to increase awareness and improve the understanding of nephrology in the context of geriatric medicine but also geriatrics in its interface with nephrology, especially in the area of chronic kidney disease.

Estimated GFR Before and After Bariatric Surgery in CKD

BACKGROUND

Several reviews have recently detailed the beneficial effects of weight loss surgery for kidney function. However, these studies have a number of limitations, including small sample size, few done in chronic kidney disease (CKD) stages 3 and 4, and many not including the main bariatric surgery procedures used in the United States today.

STUDY DESIGN

This was an observational retrospective cohort study comparing propensity score-matched bariatric surgery patients and nonsurgery control patients who were referred for, but did not have, surgery. Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy were also compared using propensity matching.

SETTING & PARTICIPANTS

Patients (714 surgery patients; 714 controls) were from a large integrated health care system, a mean of 58±8 (SD) years old, and mostly women (77%) and non-Hispanic whites (56%) and had diabetes mellitus (66%) and/or hypertension (91%).

PREDICTOR

Predictors at the time of surgery or referral to surgery were age, sex, race/ethnicity, weight, and presence of diabetes and/or hypertension.

OUTCOMES

The primary outcome for this study was change in estimated glomerular filtration rate (eGFR) from serum creatinine level over a median 3-year follow-up period.

MEASUREMENTS

Serum creatinine was used to calculate eGFR using the CKD-EPI (CKD Epidemiology Collaboration) creatinine equation.

RESULTS

Surgery patients had 9.84 (95% CI, 8.05-11.62) mL/min/1.73m² greater eGFRs than controls at a median 3 years' follow-up and RYGB patients had 6.60 (95% CI, 3.42-9.78) mL/min/1.73m² greater eGFRs than sleeve gastrectomy patients during the same period.

LIMITATIONS

This study is limited by its nonrandomized observational study design, estimation of GFR, and large changes in muscle mass, which may affect serum creatinine level independent of changes in kidney function.

CONCLUSIONS

Bariatric surgery, especially the RYGB procedure, results in significant improvements for up to 3 years in eGFRs for patients with CKD stages 3 and 4.

Competing risk of death and end-stage renal disease in incident chronic kidney disease (stages 3 to 5): the EPIRAN community-based study

BACKGROUND

Although chronic kidney disease (CKD) affects a growing number of people, epidemiologic data on incident CKD in the general population are scarce. Screening strategies to increase early CKD detection have been developed.

METHODS

From a community-based sample of 4,409 individuals residing in a well-defined geographical area, we determined the number of patients having a first serum creatinine value ≥1.7 mg/dL and present for at least 3 months that allowed us to calculate an annual incidence rate of CKD (stages 3 to 5). CKD (stages 3 to 5) was defined by estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. We also described the primary care, outcomes and risk factors associated with outcomes using competing risks analyses for these CKD patients.

RESULTS

A total of 631 incident CKD patients (stages 3 to 5) were followed-up until the occurrence of death and dialysis initiation for more than 3 years. The annual incidence rate of CKD (stages 3 to 5) was estimated at 977.7 per million inhabitants. Analyses were performed on 514 patients with available medical data. During the study, 155 patients (30.2 %) were referred to a nephrologist, 193 (37.5 %) died and 58 (11.3 %) reached end-stage renal disease and initiated dialysis. A total of 139 patients (27.6 %) had a fast decline of their renal function, 92 (18.3 %) a moderate decline and the 272 remaining patients had a physiological decline (21.1 %) or a small improvement of their renal function (33.0 %). Predictors of death found in both Cox and Fine-Gray multivariable regression models included age at diagnosis, anemia, active neoplasia and chronic heart failure, but not a low glomerular filtration rate (GFR). Age at diagnosis, anemia and a low GFR were independently associated with dialysis initiation in Cox model, but anemia was not found to be a risk factor for dialysis initiation in Fine-Gray model.

CONCLUSIONS

This large cohort study provided useful epidemiological data on incident CKD (stages 3 to 5) and stressed the need to improve the hands-on implementation of clinical practice guidelines for the evaluation and the management of CKD in primary care.

Positive Predictive Value of a Single Assessment of Estimated GFR in the Diagnosis of Chronic Kidney Disease

OBJECTIVES

The positive predictive value (PPV) of a single assessment of estimated glomerular filtration rate (eGFR) in the diagnosis of chronic kidney disease (CKD) is not known. Our objective was to determine the PPV of a single assessment of eGFR among adults with at least one eGFR <60 mL/min in their lifetime, using the Distributed Area Research and Therapeutics Network CKD natural history dataset.

METHODS

In all, 47,104 adults who were cared for by 113 practices in the United States were included. Proportions of patients in eGFR categories at baseline were calculated using the following categories: <15 mL/min, 15 to 29.99 mL/min, 30 to 44.99 mL/min, and 45 to 59.99 mL/min. Comparisons were then made between the baseline and the endpoint to identify patients who had a follow-up eGFR that remained at <60 mL/min. The proportions of patients in each eGFR category were compared baseline to endpoint using cross-tabulations. To test the proposed cutpoint, the proportions of patients who had an eGFR that remained at <60 mL/min were measured, using the cutpoints that included the highest cumulative proportion of patients. The sensitivity and specificity of that cutpoint were calculated.

RESULTS

A cutpoint of <45 mL/min was identified, yielding a PPV of 93% with a sensitivity of 28% and a specificity of 94%.

CONCLUSIONS

A valid cutpoint to screen for CKD was identified. This cutpoint may prove important to early screening for CKD while reducing the burden on the healthcare system and patients suspected of having CKD.

Chronic kidney disease and prognosis in elderly patients with cardiovascular disease: Comparison between CKD-EPI and Berlin Initiative Study-1 formulas

BACKGROUND

Chronic kidney disease (CKD) is frequent in patients with cardiovascular (CV) disease and impacts prognosis in these subjects. While current guidelines recommend the CKD-EPI equation for the estimated glomerular filtration rate (eGFR) and recognizing CKD, a new creatinine-based equation - the Berlin Initiative Study-1 (BIS-1) - was generated for elders with a high prevalence of CV disease. We assessed whether BIS-1 provided more accurate risk stratification than the CKD-EPI equation in unselected aged patients with CV disease.

METHODS

Patients aged ≥70 years who were seen consecutively at the Cardiovascular Centre of Trieste (Italy) between November 2009 and October 2013 were recruited into this study. The correlation and agreement between the BIS-1 and CKD-EPI formulas were evaluated and intra-class correlation coefficients (ICCs) were computed in order to estimate the correlation between the two formulas. Patients were followed for all-cause death, composite outcomes of all-cause death/all-cause hospitalization and all-cause death/CV hospitalization.

RESULTS

A total of 7845 subjects met the inclusion criteria for this study. GFR as estimated with the BIS-1 and the CKD-EPI equation was highly correlated (ICC: 0.81; 95% confidence interval [CI]: 0.79-0.82; p < 0.0001). When allocating patients in Kidney Disease Improving Global Outcomes classes of eGFR, compared to CKD-EPI, the BIS-1 formula reclassified 2720 (34.7%) patients: 53 (1.9%) were placed in a better class and 2667 (98.1%) were placed in a worse class. Multivariable Cox models showed that BIS-1 compared to CKD-EPI had a significantly better accuracy for predicting death (NRI: 0.12; 95% CI: 0.03-0.19; p = 0.001), death/CV hospitalization (net reclassification improvement [NRI]: 0.34; 95% CI: 0.27-0.38; p < 0.001) and death/all-cause hospitalization (NRI: 0.14; 95% CI: 0.06-0.21; p = 0.001).

CONCLUSIONS

The BIS-1 formula is better than the CKD-EPI formula for risk stratification of CKD in elderly people with CV disease.

Shear wave elastography in chronic kidney disease: a pilot experience in native kidneys

Background

There currently is a need for a non-invasive measure of renal fibrosis. We aim to explore whether shear wave elastography (SWE)-derived estimates of tissue stiffness may serve as a non-invasive biomarker that can distinguish normal and abnormal renal parenchymal tissue.

Methods

Participants with CKD (by estimated GFR) and healthy volunteers underwent SWE. Renal elasticity was estimated as Young’s modulus (YM) in kilopascals (kPa). Univariate Wilcoxon rank-sum tests were used.

Results

Twenty-five participants with CKD (median GFR 38 mL/min; quartile 1, quartile 3 28, 42) and 20 healthy controls without CKD underwent SWE performed by a single radiologist. CKD was associated with increased median YM (9.40 [5.55, 22.35] vs. 4.40 [3.68, 5.70] kPa; p = 0.002) and higher median intra-subject inter-measurement estimated YM’s variability (4.27 [2.89, 9.90] vs. 1.51 [1.21, 2.05] kPa; p < 0.001).

Conclusions

SWE-derived estimates of renal stiffness and intra-subject estimated stiffness variability are higher in patients with CKD than in healthy controls. Renal fibrosis is a plausible explanation for the observed difference in YM. Further studies are required to determine the relationship between YM, estimated renal stiffness, and renal fibrosis severity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0120-7) contains supplementary material, which is available to authorized users.

Major bleeding risk prediction using Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations in acute coronary syndrome

BACKGROUND

Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations estimate glomerular filtration rate more accurately than the Modification of Diet in Renal Disease (MDRD) Study equation. Our aim was to evaluate whether CKD-EPI equations based on serum creatinine and/or cystatin C (CysC) predict risk for major bleeding (MB) more accurately than the MDRD Study equation in patients with non-ST-segment elevation acute coronary syndromes (ACS).

MATERIALS AND METHODS

Three hundred and fifty consecutive subjects with non-ST-segment elevation ACS (68 ± 12 years, 70% male) were studied. Glomerular filtration rate was estimated using the CKD-EPI and MDRD Study equations. The primary endpoint was the occurrence of MB during the follow-up, which was defined according to the Bleeding Academic Research Consortium Definition criteria as bleeding types 3-5.

RESULTS

During the median follow-up of 589 days (interquartile range, 390-986), 27 patients had MB (0.04% events per person year). Patients with MB had worse kidney function parameters, regardless of the estimating equation used (P < 0.001). After multivariate Cox regression adjustment, both CysC-based CKD-EPI equations were independent predictors of MB (CKD-EPI(creatinine-cystatin) C per mL/min/1.73 m(2), HR = 0.973 (95%CI 0.955-0.991; P = 0.003) and CKD-EPI(cystatin) C per mL/min/1.73 m(2), HR = 0.976 (95%CI 0.976-0.992; P = 0.003), while the CKD-EPI(creatinine) and MDRD equations did not achieve statistical significance. Both CKD-EPI(creatine-cystatin) C and CKD-EPI(cystatin) C were associated with a significant improvement in MB risk reclassification.

CONCLUSIONS

In this cohort of non-ST-segment elevation ACS patients with relatively preserved renal function, both CysC-based CKD-EPI equations improved ability to predict risk for MB and were superior to other equations for this application.

Cystatin C-based CKD-EPI equations and N-terminal pro-B-type natriuretic peptide for predicting outcomes in acutely decompensated heart failure

BACKGROUND

In patients with acute decompensated heart failure (ADHF), both natriuretic peptides and renal impairment predict adverse outcomes. Our aim was to evaluate the complementary prognosis role of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and the newly developed Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations based on cystatin C (CysC) for glomerular filtration rate (GFR) estimation in ADHF patients.

HYPOTHESIS

Renal impairment assessed by CysC-based CKD-EPI equations and natriuretic peptides have complementary prognostic value in ADHF patients.

METHODS

The study included 613 consecutive patients presenting with ADHF. At admission, plasma levels of NT-proBNP and CysC were determined. The GFR was estimated using CysC-based CKD-EPI equations. The primary endpoint was death from any cause and heart failure readmission.

RESULTS

During the median follow-up of 365 days (interquartile range, 227-441 days), 323 patients (0.65 %patient-year) died or were readmitted for heart failure. After multivariate adjustment, estimated GFR <60 mL/min/1.73 m(2) and NT-proBNP >3251 pg/mL were independent predictors of adverse outcomes (P < 0.01). The combination of GFR <60 mL/min/1.73 m(2) and NT-proBNP >3251 pg/mL was associated with the highest risk of adverse outcomes. Furthermore, reclassification analyses demonstrated that use of both NT-proBNP and CysC-based CKD-EPI equations resulted in improving the accuracy for adverse outcomes prediction.

CONCLUSIONS

In patients with ADHF, the combination of NT-proBNP with estimated GFR using CysC-based CKD-EPI equations better predicts outcomes than either parameter alone and adds valuable complementary prognosis information to other established risk factors.

Comparison of risk prediction with the CKD-EPI and MDRD equations in acute decompensated heart failure

BACKGROUND

Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations estimate glomerular filtration rate (eGFR) more accurately than the Modification of Diet in Renal Disease (MDRD) equation. The aim of this study was to evaluate whether CKD-EPI equations based on serum creatinine and/or cystatin C (CysC) predict risk for adverse outcomes more accurately than the MDRD equation in a hospitalized cohort of patients with acute decompensated heart failure (ADHF).

METHODS AND RESULTS

A total of 526 subjects with ADHF were studied. Blood was collected within 48 hours from admission. eGFR was calculated with the use of MDRD and CKD-EPI equations. The occurrences of mortality and heart failure (HF) hospitalization were recorded. Over the study period (median 365 days [interquartile range 238-370]), 305 patients (58%) died or were rehospitalized for HF. Areas under the receiver operator characteristic curves for CKD-EPI CysC and CKD-EPI creatinine-CysC equations were significantly higher than that for the MDRD equation, especially in patients with >60 mL min(-1) 1.73 m(-2). After multivariate adjustment, all eGFR equations were independent predictors of adverse outcomes (P < .001). However, only CKD-EPI CysC and CKD-EPI creatinine-CysC equations were associated with significant improvement in reclassification analyses (net reclassification improvements 10.8% and 12.5%, respectively).

CONCLUSIONS

In patients with ADHF, CysC-based CKD-EPI equations were superior to the MDRD equation for predicting mortality and/or HF hospitalization especially in patients with >60 mL min(-1) 1.73 m(-2), and both CKD-EPI equations improved clinical risk stratification.

GFR estimating equations: getting closer to the truth?

The application of serum creatinine and cystatin C in patients with CKD has been limited to using estimated glomerular filtration rate (eGFR). Criteria for choosing the best GFR estimating equation are 1) accuracy in estimating measured GFR, 2) optimal discrimination of clinical outcomes, and 3) association with CKD risk factors and outcomes similar to that of measured GFR. Notably, these criteria are often not in agreement; and while the last criterion is the most important, it has been widely overlooked. The primary problem with eGFR is that the non-GFR determinants of serum creatinine and cystatin C, as well as their surrogates (age, sex, and race), associate with CKD risk factors and outcomes. This leads to a distorted understanding of CKD, though eGFR based on serum creatinine appears to be less biased than eGFR based on cystatin C. Because of this problem, the use of eGFR should be limited to settings where knowing actual GFR is relevant and eGFR is more informative about GFR than serum creatinine or cystatin C alone. Such settings include staging CKD severity by GFR and dosing medications cleared by glomerular filtration. Alternatively, the diagnosis of CKD, the longitudinal progression of CKD, and prognostic models for CKD are settings where serum creatinine and cystatin C can be better applied and interpreted without eGFR.

Do living kidney donors have CKD?

Living kidney donor transplantation is an increasingly used treatment for end-stage renal disease because it both confers excellent outcomes to transplant recipients, and is considered a safe procedure for prospective donors. The short- and long-term safety of prospective donors is paramount to the continued success of living donation. Although the initial experience with living kidney donors mostly included the healthiest donors, increasing need for organs and secular trends in the general population have subtly reshaped prevailing suitability criteria for donation. As the practice of living donation evolved over time, our understanding of kidney disease has also changed as we embraced the framework of the K-DOQI guidelines. It is not uncommon for donors to fit into some of the K-DOQI guidelines paradigms of risk and disease; however, whether there is a true biological consequence or whether it is a merely semantic conundrum remains unclear. Regardless, this is an important issue, and therefore future efforts should aim at addressing this matter.

Assessing renal parenchymal volume on unenhanced CT as a marker for predicting renal function in patients with chronic kidney disease

OBJECTIVES

To estimate renal volume in chronic kidney disease (CKD) patients using a semiautomated software and compare them with split renal function estimates from radionuclide renogram (RR). We proposed that renal volume from unenhanced computed tomography (CT) scans may serve as surrogate marker for assessing renal function in CKD patients.

MATERIALS AND METHODS

Unenhanced multidetector CT scans of 26 patients with CKD (estimated glomerular filtration rate [eGFR] <60 mL/kg/body surface area [BSA]) and 10 controls (eGFR >60 mL/kg/BSA) were analyzed to calculate renal volumes using a semiautomated software (AMIRAV5.2.0). Volumes obtained were then correlated with corresponding eGFR and split renal function estimates from RR. Volumes were also compared with those obtained on enhanced scans in 10 cases (five disease group, five controls). Bland-Altman analysis was used to assess agreement between methods.

RESULTS

A moderately positive correlation was found between renal volume obtained on unenhanced CT and eGFR (r = 0.65, P < .0001), whereas a significantly high correlation with split function estimates from RR (r = 0.95, P < .001) was found. Bland-Altman analysis revealed a good agreement between renal volume from CT and renal function from RR (34/36 observations were within 95% CI and there were two outliers). Correlation between volumes obtained from unenhanced and enhanced CT scans was also significant (r = 0.96).

CONCLUSION

In patients with CKD, renal volume derived from unenhanced CT can possibly serve as a surrogate marker for assessing and monitoring renal function reserves to plan further management.

Time to differentiate 'decreased kidney function' from 'kidney disease': towards improving the definition of chronic kidney disease

Chronic kidney disease (CKD) has become an 'epidemic' worldwide, since the publication of K/DOQI guidelines in 2002. This classification indeed has raised the profile of CKD worldwide. However, despite limitations of the glomerular filtration rate (GFR) estimating equations, the majority of this epidemic is caused by the large number of persons with stage 3 CKD, with many elderly individuals with 'low-normal GFR' being diagnosed with CKD, when, in fact, the majority of those may not have the disease, and a handful of resources being utilized in investigating these relatively 'low-risk patients' with 'decreased eGFR' without CKD. Recently, concerns have been raised by nephrologists about this classification system, and I strongly feel that it is important to differentiate 'decreased kidney function' from 'kidney disease', as the GFR estimating equations predict renal function only and nothing else; therefore, I propose some modifications to improve the current classification, so that limited resources and efforts are effectively focused on managing high-risk patients.

Association between physical activity and kidney function: National Health and Nutrition Examination Survey

INTRODUCTION

Chronic kidney disease is a condition characterized by the deterioration of the kidney's ability to remove waste products from the body. Although treatments to slow the progression of the disease are available, chronic kidney disease may eventually lead to a complete loss of kidney function. Previous studies have shown that physical activities of moderate intensity may have renal benefits. Few studies have examined the effects of total movement on kidney function. The purpose of this study was to determine the association between time spent at all levels of physical activity intensity and sedentary behavior and kidney function.

METHODS

Data were obtained from the 2003-2004 and 2005-2006 National Health and Nutrition Examination Survey, a cross-sectional study of a complex, multistage probability sample of the US population. Physical activity was assessed using an accelerometer and questionnaire. Glomerular filtration rate (eGFR) was estimated using the Modification of Diet in Renal Disease study formula. To assess linear associations between levels of physical activity and sedentary behavior with log-transformed estimated GFR (eGFR), linear regression was used.

RESULTS

In general, physical activity (light and total) was related to log eGFR in females and males. For females, the association between light and total physical activity with log eGFR was consistent regardless of diabetes status. For males, the association between light and total physical activity and log eGFR was only significant in males without diabetes.

CONCLUSIONS

When examining the association between physical activity, measured objectively with an accelerometer, and kidney function, total and light physical activities were found to be positively associated with kidney function.

Prognostic assessment of estimated glomerular filtration rate by the new Chronic Kidney Disease Epidemiology Collaboration equation in comparison with the Modification of Diet in Renal Disease Study equation

BACKGROUND

Systematic reporting of estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) Study equation is recommended for detection of chronic kidney disease and prediction of cardiovascular (CV) risk. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is a newly developed and validated formula for eGFR that is more accurate at normal or near-normal eGFR. We aimed to assess the incremental prognostic accuracy of eGFR(CKD-EPI) versus eGFR(MDRD) in subjects at increased risk for CV disease.

METHODS

We performed a post hoc analysis of the VALIANT trial that enrolled 14,527 patients with acute myocardial infarction with signs and symptoms of heart failure and/or left ventricular systolic dysfunction. The eGFR(MDRD) and eGFR(CKD-EPI) were computed using age, gender, race, and baseline creatinine level. Patients were categorized according to their eGFR using each equation. To assess the incremental prognostic value of eGFR(CKD-EPI), the net reclassification improvement was calculated for the composite end point of CV death, recurrent myocardial infarction, heart failure, or stroke.

RESULTS

Twenty-four percent of the subjects were reclassified into a different eGFR category using eGFR(CKD-EPI). The composite end point occurred in 33% of the subjects in this cohort. Based on eGFR(CKD-EPI), subjects reclassified into a higher eGFR experienced fewer events than those reclassified into a lower eGFR (21% vs 43%). In unadjusted analyses, the composite end point risk in subjects with eGFR between 75 and 90 mL/min per 1.73 m(2) was comparable with the referent group (eGFR between 90 and 105) using eGFR(MDRD) (hazard ratio 1.1, 95% CI 0.9-1.2) but was significantly higher using eGFR(CKD-EPI) (hazard ratio 1.2, 95% CI 1.1-1.4). The net reclassification improvement for eGFR(CKD-EPI) over eGFR(MDRD) was 8.7%.

CONCLUSION

The CKD-EPI equation provides more accurate risk stratification than the MDRD Study equation in patients at high risk for CV disease, including identification of increased risk at mildly decreased eGFR.

Relative performance of the MDRD and CKD-EPI equations for estimating glomerular filtration rate among patients with varied clinical presentations

BACKGROUND

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was developed using both CKD and non-CKD patients to potentially replace the Modification of Diet in Renal Disease (MDRD) equation that was derived with only CKD patients. The objective of our study was to compare the accuracy of the MDRD and CKD-EPI equations for estimating GFR in a large group of patients having GFR measurements for diverse clinical indications.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

A cross-sectional study was conducted of patients who underwent renal function assessment for clinical purposes by simultaneous measurements of serum creatinine and estimation of GFR using the MDRD and CKD-EPI equations and renal clearance of iothalamate (n = 5238).

RESULTS

Bias compared with measured GFR (mGFR) varied for each equation depending on clinical presentation. The CKD-EPI equation demonstrated less bias than the MDRD equation in potential kidney donors (-8% versus -18%) and postnephrectomy donors (-7% versus -15%). However, the CKD-EPI equation was slightly more biased than the MDRD equation in native CKD patients (6% versus 3%), kidney recipients (8% versus 1%), and other organ recipients (9% versus 3%). Among potential kidney donors, the CKD-EPI equation had higher specificity than the MDRD equation for detecting an mGFR <60 ml/min per 1.73 m(2) (98% versus 94%) but lower sensitivity (50% versus 70%).

CONCLUSIONS

Clinical presentation influences the estimation of GFR from serum creatinine, and neither the CKD-EPI nor MDRD equation account for this. Use of the CKD-EPI equation misclassifies fewer low-risk patients as having reduced mGFR, although it is also less sensitive for detecting mGFR below specific threshold values used to define CKD stages.

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.

Serum uric acid predicts progression of subclinical coronary atherosclerosis in individuals without renal disease

OBJECTIVE

To examine uric acid (UA) as a possible predictor of the progression of coronary artery calcification (CAC) using data from the prospective Coronary Artery Calcification in Type 1 Diabetes (CACTI) Study.

RESEARCH DESIGN AND METHODS

CAC was measured by electron beam tomography at the baseline and at a follow-up 6.0±0.5 years later. The study population included 443 participants with type 1 diabetes and 526 control subjects who were free of diagnosed coronary artery disease at baseline. The presence of renal disease was defined by the presence of albuminuria and/or low glomerular filtration rate.

RESULTS

In subjects without renal disease, serum UA predicted CAC progression (odds ratio 1.30 [95% CI 1.07-1.58], P=0.007) independent of conventional cardiovascular risk factors including diabetes and the presence of metabolic syndrome.

CONCLUSIONS

Serum UA levels predict the progression of coronary atherosclerosis and may be useful in identifying who is at risk for vascular disease in the absence of significant chronic kidney disease.

Racial and ethnic differences in albuminuria in individuals with estimated GFR greater than 60 mL/min/1.73 m(2): results from the Kidney Early Evaluation Program (KEEP)

BACKGROUND

Albuminuria is an important marker for chronic kidney disease and progression to end-stage renal disease in the general population; understanding racial and ethnic differences can help inform efforts to reduce health disparities. We sought to estimate independent associations of race/ethnicity with albuminuria to determine whether observed differences were attributable to known kidney disease risk factors.

METHODS

This cross-sectional study included 64,161 Kidney Early Evaluation Program (KEEP) participants, 2000-2008, with estimated glomerular filtration rate > or = 60 mL/min/1.73 m(2), not on regular dialysis therapy, and without a previous kidney transplant. Albuminuria (urine albumin-creatinine ratio > or = 30 mg/g) was examined by self-reported race and ethnicity. Covariates were age, sex, educational level, body mass index, diabetes status or glucose level, hypertension status or blood pressure measurement, smoking status, health insurance status, and geographic region.

RESULTS

Albuminuria prevalences were 8% (n = 2,303) in whites, 11% (n = 2,310) in African Americans, 9% (n = 730) in Hispanics, 10% (n = 381) in Asians, and 15% (n = 344) in American Indians/Alaska Natives. Compared with whites, odds of albuminuria were higher for all groups after multivariate adjustment. Odds were highest for American Indians/Alaska Natives (adjusted OR, 1.93; 95% CI, 1.70-2.20), then Asians (adjusted OR, 1.42; 95% CI, 1.26-1.61), African Americans (adjusted OR, 1.38; 95% CI, 1.29-1.47), and Hispanics (adjusted OR, 1.19; 95% CI, 1.08-1.31).

CONCLUSIONS

In the KEEP study population, albuminuria prevalence was higher in African Americans, Hispanics, Asians, and American Indians/Alaska Natives than in non-Hispanic whites, suggesting a need for screening for early detection of kidney damage, especially in people at increased risk, in the community primary care setting.

Hypertension during pregnancy is associated with coronary artery calcium independent of renal function

BACKGROUND

Hypertension during pregnancy (HDP) increases the risk of future coronary heart disease (CHD), but it is unknown whether this association is mediated by renal injury. Reduced renal function is both a complication of HDP and a risk factor for CHD.

METHODS

Logistic regression models were fit to examine the association between a history of HDP and the presence and extent of coronary artery calcification (CAC), a measure of subclinical coronary artery atherosclerosis, in 498 women from the Epidemiology of Coronary Artery Calcification Study (mean age 63.3 +/- 9.3 years).

RESULTS

Fifty-two (10.4%) women reported a history of HDP. After adjusting for age at time of study participation, HDP was associated with increased serum creatinine later in life (p = 0.014). HDP was positively associated with the presence of CAC after adjusting for age at time of study participation (OR = 2.7, 95% CI 1.4-5.4). This association was slightly attenuated with adjustment for body size and blood pressure (OR = 2.4, 95% CI 1.2-4.9) but was not further attenuated with adjustment for serum creatinine and urinary albumin/creatinine ratio (OR = 2.6, 95% CI 1.3-5.3). Results were similar for CAC extent.

CONCLUSIONS

HDP may increase a woman's risk of future CHD beyond traditional risk factors and renal function. Women with a history of HDP should be monitored for potential increased risk of CHD as they age.

The choice of estimating equations for glomerular filtration rate significantly affects the prevalence of chronic kidney disease in a multi-ethnic population during health screening

BACKGROUND

Patients present to the National University Hospital of Singapore and select one of several health screening packages after counselling. The prevalence of chronic kidney disease (CKD) in this population when different glomerular filtration rate (GFR) estimating equations are used has not been examined.

METHODS

Demographic data and urinalyses of patients from 2000 to 2005 were extracted from laboratory computer databases and analysed. CKD was classified into stages according to the US National Kidney Foundation guidelines by eGFR (mL/min per 1.73 m(2)) using the four-variable Modification of Diet in Renal Disease equation. GFR of ethnic Chinese was also estimated using Ma's equation 8 (cGFR). Stage 1 and normal (eGFR or cGFR > 90) was discriminated by urinary microscopy or dipstick for proteinuria, albuminuria, hematuria or leukocyturia.

RESULTS

There were 3979 screenings (55.9% males, 61.9% Chinese). Means: age = 47.0 +/- 12.3 years, creatinine = 80.1 +/- 26.5 micromol/L, eGFR = 89.6 +/- 19.7, cGFR = 110.8 +/- 23.8 and (eGFR + cGFR) = 102.5 +/- 24.9. By eGFR in all patients, the prevalence of CKD was 45.7%, 50.6%, 3.3%, 0.3% and 0.08% for stages normal or 1, 2, 3, 4 and 5, respectively. For Chinese patients only, eGFR and cGFR resulted in a different distribution (eGFR%/cGFR%): 24.9/50.5, 15.2/29.3, 56.8/19.7, 3/0.8, 0.2/0.2, 0/0 for stages 'Normal', 1, 2, 3, 4 and 5, respectively (P < 0.001).

CONCLUSION

The prevalence of moderate to severe CKD (stage 3 to 5) in patients presenting for health screening in Singapore was 3.7%. Notably, the prevalence of mild to moderate CKD (stages 1, 2 and 3) in Chinese patients was affected significantly by the choice of GFR estimating equation.

Glomerular filtration rate measurement and prediction equations

Chronic kidney disease (CKD) is defined as the presence of kidney damage or a glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) for three or more months. Measurement of serum creatinine is the most commonly used method to evaluated kidney function, but it must be included in formulas to estimate GFR, adjusting for age, gender and ethnicity, such as the Modification of Diet in Renal Disease (MDRD) study equation. The performance of this equation is acceptable for patients with CKD but appears to under-estimate GFR in populations with unknown kidney status. A new formula has been developed recently. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation appears to perform better than the MDRD equation. Cystatin C has been widely evaluated as a marker for GFR and seems to be more sensitive than creatinine. The aim of this review is to discuss the recommendations for detecting CKD, emphasizing the characteristics and limitations of GFR estimating equations and pitfalls in the evaluation of urinary albumin excretion.

The science of Stewardship: due diligence for kidney donors and kidney function in living kidney donation--evaluation, determinants, and implications for outcomes

Living kidney donor transplantation is now a common treatment for ESRD because it provides excellent outcomes to transplant recipients and is considered a safe procedure for prospective donors. The short- and long-term safety of prospective donors is paramount to the continued success of this procedure. Whereas the initial experiences with living kidney donors mostly included the healthiest, the increase in the need for organs and the changing demographic characteristics of the general population have subtly reshaped the suitability for donation. Kidney function assessment is a critical component of the evaluation of prospective donors; therefore, special emphasis is usually placed on this aspect of the evaluation. At the same time, consideration of kidney function after donation is important because it assists with the determination of renal health in donors. This review summarizes the process of predonation kidney function assessment, determinants of pre- and postdonation renal function, and, importantly, the potential implications of kidney function to the long-term outcomes of kidney donors.

Lithium effect on renal glomerular function in individuals with intellectual disability

OBJECTIVE

The current study evaluated the effects of chronic administration of lithium on renal functioning in an intellectually disabled population.

METHODS

Fifty-seven lithium-treated individuals were compared with 24 behaviorally symptomatic controls using a retrospective chart review method. Serum creatinine levels and creatinine clearance activities were compared at baseline, at the time of peak creatinine levels, and at the end of the study in 2006.

RESULTS

The mean length of lithium administration was 8.76 years (range, 1-23 years). Chronic lithium administration yielded a significant increase in peak serum creatinine levels and a decrease in the corresponding creatinine clearance activity. Of the subjects, 22.8% had peak creatinine levels of 1.5 mg or higher per 100 mL (a common threshold for renal insufficiency). This contrasted with 0% (none) for the symptomatic control subjects (P = 0.008). In addition, 26.3% of the lithium-treated subjects had creatinine clearance activities less than 55 mL/min and 17.5% had less than 50 mL/min, both indicative of renal insufficiency, versus none of the symptomatic control subjects (P = 0.004 and P = 0.029, respectively). With lithium withdrawal, further deterioration of renal function did not occur in most cases, and many showed improvement, with decreases in serum creatinine levels and increases in creatinine clearance activity.

CONCLUSIONS

Chronic administration of lithium led to clinically significant increases in serum creatinine levels and decreases in creatinine clearance in lithium-treated intellectually disabled individuals.