Rate of kidney function decline associates with mortality

Visit-to-visit variability in estimated glomerular filtration rate predicts hospitalization and death due to cardiovascular events

BACKGROUND

Greater variability in estimated glomerular filtration rate (eGFR) is associated with mortality in patients with chronic kidney disease (CKD). However, the association between eGFR variability and cardiovascular (CV) mortality and/or end-stage kidney disease (ESKD) in the CKD population is not very clear. This study aimed to clarify whether such an association exists.

METHODS

We analyzed a final cohort of 2869 eligible Asian patients with CKD. Patients were stratified into three groups according to eGFR variability during the first year and were followed-up for a median of 3.15 years. Primary CV composite endpoints were hospitalization or death due to CV events, and renal composite endpoints were doubling of serum creatinine levels or ESKD. Multivariate Cox hazard models adjusted for classical risk factors and eGFR slope were used to examine the CV and renal risk associated with eGFR variability.

RESULTS

CV endpoints were observed in 14 (2.89%), 25 (5.69%), and 41 (10.79%) patients and renal endpoints were observed in 165 (27.6%), 235 (39.0%), and 298 patients (50.9%) in the lowest, intermediate, and highest tertiles of eGFR variability, respectively. Patients in the highest tertile were at a significantly higher risk for CV events (hazard ratio 1.90; 95% confidence interval 1.03-3.71) than those in the lowest tertile. However, there was no association between eGFR variability and renal endpoints.

CONCLUSIONS

Variability in eGFR can predict CV outcomes among patients with CKD.

Repeated measurements of renal function in evaluating its decline in cats

OBJECTIVES

The aim of this study was to describe the variability in renal function markers in non-azotaemic and azotaemic cats, and also the rate of change in the markers.

METHODS

Plasma creatinine concentration and its reciprocal, glomerular filtration rate (GFR) and urine specific gravity (USG) were studied as markers of renal function in client-owned cats. GFR was determined using a corrected slope-intercept iohexol clearance method. Renal function testing was performed at baseline and a second time point. The within-population variability (coefficient of variation; CV%) was determined at the baseline time point. Within-individual variability (CV%) and rate of change over time were determined from the repeated measurements.

RESULTS

Twenty-nine cats were included in the study, of which five had azotaemic chronic kidney disease. The within-individual variability (CV%) in creatinine concentration was lower in azotaemic cats than in non-azotaemic cats (6.81% vs 8.82%), whereas the within-individual variability in GFR was higher in azotaemic cats (28.94% vs 19.98%). The within-population variability was greatest for USG (67.86% in azotaemic cats and 38.00% in non-azotaemic cats). There was a negative rate of change in creatinine concentration in azotaemic and non-azotaemic cats (-0.0265 and -0.0344 µmol/l/day, respectively) and a positive rate of change of GFR in azotaemic and non-azotaemic cats (0.0062 and 0.0028 ml/min/day, respectively).

CONCLUSIONS AND RELEVANCE

The within-individual variability data suggest creatinine concentration to be the more useful marker for serial monitoring of renal function in azotaemic cats. In contrast, in non-azotaemic cats, GFR is a more useful marker for serial monitoring of renal function. The majority of cats with azotaemic CKD did not have an appreciable decline in renal function during the study.

Kidney Function Decline in Patients with CKD and Untreated Hepatitis C Infection

BACKGROUND AND OBJECTIVES

Studies evaluating the role of hepatitis C viral (HCV) infection on the progression of CKD are few and conflicting. Therefore, we evaluated the association of untreated HCV on kidney function decline in patients with stage 3-5 CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective cohort study included members of Kaiser Permanente Southern California and Kaiser Permanente Mid-Atlantic States aged ≥18 years, with incident HCV and CKD diagnoses from January 1, 2004 to December 31, 2014. We used generalized estimating equations to compare the rate of change in eGFR between those with HCV and CKD versus CKD alone, adjusting for covariates. Cox proportional hazards models compared the risk of 25% decrease in eGFR and ESKD (defined as progression to eGFR<15 ml/min per 1.73 m2 on two or more occasions, at least 90 days apart) in those with HCV and CKD versus CKD alone, adjusting for covariates.

RESULTS

We identified 151,974 patients with CKD only and 1603 patients with HCV and CKD who met the study criteria. The adjusted annual decline of eGFR among patients with HCV and CKD was greater by 0.58 (95% confidence interval [95% CI], 0.31 to 0.84) ml/min per 1.73 m2, compared with that in the CKD-only population (HCV and CKD, -1.61; 95% CI, -1.87 to -1.35 ml/min; CKD only, -1.04; 95% CI, -1.06 to -1.01 ml/min). Adjusted for covariates, the hazard for a 25% decline in eGFR and for ESKD were 1.87 (95% CI, 1.75 to 2.00) and 1.93 (95% CI, 1.64 to 2.27) times higher among those with HCV and CKD, respectively, compared with those with CKD only.

CONCLUSIONS

Untreated HCV infection was associated with greater kidney function decline in patients with stage 3-5 CKD.

Predialysis Kidney Function and Its Rate of Decline Predict Mortality and Hospitalizations After Starting Dialysis

OBJECTIVE

To determine whether kidney function level and its rate of decline in the immediate predialysis period among veterans transitioning to end-stage renal disease (ESRD) predict postdialysis mortality and hospitalization.

PATIENTS AND METHODS

In 19,985 veterans transitioning to ESRD during the period October 1, 2007, to March 30, 2014, we examined kidney function and its slope over the final year of the pre-ESRD(prelude) period. Two categories of low vs high estimated glomerular filtration rate (eGFR, dichotomized at 10 mL/min/1.73 m²) and slow vs fast slope (dichotomized at -10 mL/min/1.73 m²/y) were combined into 4 groups. Their associations with 12-month post-ESRD all-cause and cardiovascular (CV) mortality and hospitalization rates were examined in adjusted models accounting for clinical characteristics and laboratory measurements at transition.

RESULTS

Patients, 66±11 years old, and 34% blacks, had a median (interquartile range) eGFR at transition and slope of 9.7 (7.1-13.3) mL/min/1.73 m² and -10.5 (-18.8 to -5.9) mL/min/1.73 m²/y, respectively. Patients with a low eGFR and slow slope had the lowest 12-month all-cause and CV mortality risks and hospitalization rate. Conversely, patients with high eGFR and fast slope had the highest risk of all-cause and CV mortality and hospitalization rate compared with patients with a low eGFR and slow slope. This relationship persisted in sensitivity analyses, including propensity scoring.

CONCLUSION

A kidney profile of a low eGFR and slow slope in the prelude period is associated with favorable early dialysis outcomes in veteran patients. Trials to examine a more conservative approach to dialysis are warranted.

Abrupt Decline in Kidney Function Precipitating Initiation of Chronic Renal Replacement Therapy

INTRODUCTION

Abrupt declines in kidney function often occur in patients with advanced chronic kidney disease and may exacerbate the need to initiate dialysis treatment. It is unclear how frequently such events occur in patients transitioning to chronic dialysis therapy, and what outcomes they are associated with.

METHODS

We examined a national cohort of 23,349 US veterans with incident end-stage renal disease (ESRD) and with available pre-ESRD estimated glomerular filtration rate (eGFR) to identify abrupt declines in kidney function, defined as an unexpected >50% decrease in eGFR at the time of chronic dialysis transition. Associations with all-cause mortality and with renal recovery were examined in Cox proportional hazard and competing risk regression models.

RESULTS

A total of 4804 (21%) patients experienced an abrupt decline in kidney function at dialysis transition. Renal recovery occurred in 586 (12.2%) and 297 (1.6%) patients with and without an abrupt decline, respectively (adjusted subhazard ratio: 4.42; 95% confidence interval [CI]: 3.72-5.27; P < 0.001). In the first 6 months after dialysis transition 1178 patients (24.5%) with abrupt decline died (annualized mortality rate 574/1000 patient-years), compared with 2354 deaths (12.7%) in patients without abrupt decline (274 deaths/1000 patient-years). An abrupt decline was associated with 45% higher mortality after multivariable adjustments (hazard ratio: 1.45; 95% CI: 1.33-1.57).

CONCLUSION

Abrupt declines in kidney function are common in patients transitioning to chronic dialysis, and are associated with higher mortality. Patients with abrupt declines also experience a higher rate of renal recovery; hence, careful attention to residual kidney function is warranted in these patients.

The Effects of eGFR Change on CVD, Renal, and Mortality Outcomes in a Hypertensive Cohort Treated With 3 Different Antihypertensive Medications

BACKGROUND

Impaired renal function is a risk factor for cardiovascular disease, end-stage renal disease (ESRD), and mortality. The impact of short-term renal function decline on outcomes is less well studied. The association of antihypertensive medications with the impact of short-term estimated glomerular filtration rate (eGFR) decline is not known.

METHODS

We examined 20,207 hypertensive participants with baseline and 2-year creatinine levels from which eGFR changes were estimated. The associations between eGFR change with incident coronary heart disease (CHD), stroke, heart failure (HF), all-cause mortality, and ESRD during 2.9 years of in-trial follow up, and with mortality during in-trial and post-trial follow-up (7.6 years), were studied. Results were assessed by primary hypertension (HTN) treatment (chlorthalidone, lisinopril, and amlodipine) and adjusted for baseline eGFR levels.

RESULTS

In the short run, an eGFR decline below the cohort median (-1.28 ml/minute/1.73 m2/2 years) vs. above the median, or a 5 ml/min/1.73 m2/year decline vs. no decline, was associated with significant hazard risk for CHD (1.06-1.28), HF (1.24-1.91), ESRD (2.84-6.01), and mortality (1.08-1.19), but not with stroke risk. In the long term, there was a significant association with mortality (1.11-1.34). Interaction terms for outcomes by antihypertensive treatments were not statistically significant except for ESRD between amlodipine vs. chlorthalidone (hazard ratio: 3.17 [2.59, 3.88] vs. 2.41 [1.98, 2.97]; P interaction = 0.005) for a 5 ml/min/1.73 m2/year eGFR decline.

CONCLUSION

Decline in eGFR over 2 years is associated with increased risk of clinical outcomes beyond the effects of baseline eGFR. These risks were the same irrespective of the primary medication used to treat HTN.

Fast GFR decline and progression to CKD among primary care patients with preserved GFR

BACKGROUND

Fast glomerular filtration rate (GFR) decline is associated with adverse outcomes, but the associated risk factors among patients without chronic kidney disease (CKD) are not well defined.

METHODS

From a primary care registry of 37,796, we identified 2219 (6%) adults with at least three estimated (e)GFR values and a baseline eGFR between 60 and 119 ml/min/1.73 m² during an observation period of 8 years. We defined fast GFR decline as > 5 ml/min/1.73 m² per year. The outcome measure was incident CKD (eGFR < 60 ml/min/1.73 m²). Clinical and demographic characteristics were compared using Chi-square and independent-samples t tests.

RESULTS

Older age, African-American race, unmarried status, hypertension and type 2 diabetes were more common in both fast decliners and those who developed incident CKD (p < 0.0001 to < 0.05). Lower neighborhood socioeconomic status, current smoking and baseline eGFR 90-119 ml/min/1.73 m² were associated with fast decline (p < 0.01), while baseline eGFR 60-74 ml/min/1.73 m² with incident CKD (p < 0.05). In multivariate regression models, among fast decliners with mildly reduced baseline eGFR (60-89 ml/min/1.73 m²), older age was significantly associated with incident CKD [odds ratio (OR) 1.04; 95% CI 1.01-1.08], and among those with normal baseline eGFR (≥ 90-119 ml/min/1.73 m²), type 2 diabetes was significantly associated with incident CKD (OR 3.83; 95% CI 1.35-10.89).

CONCLUSIONS

Among primary care patients without CKD, GFR is checked infrequently. We have identified patients at high risk of progressive CKD, in whom we suggest a closer monitoring of renal function.

Renal function monitoring in heart failure - what is the optimal frequency? A narrative review

The second most common cause of hospitalization due to adverse drug reactions in the UK is renal dysfunction due to diuretics, particularly in patients with heart failure, where diuretic therapy is a mainstay of treatment regimens. Therefore, the optimal frequency for monitoring renal function in these patients is an important consideration for preventing renal failure and hospitalization. This review looks at the current evidence for optimal monitoring practices of renal function in patients with heart failure according to national and international guidelines on the management of heart failure (AHA/NICE/ESC/SIGN). Current guidance of renal function monitoring is in large part based on expert opinion, with a lack of clinical studies that have specifically evaluated the optimal frequency of renal function monitoring in patients with heart failure. Furthermore, there is variability between guidelines, and recommendations are typically nonspecific. Safer prescribing of diuretics in combination with other antiheart failure treatments requires better evidence for frequency of renal function monitoring. We suggest developing more personalized monitoring rather than from the current medication-based guidance. Such flexible clinical guidelines could be implemented using intelligent clinical decision support systems. Personalized renal function monitoring would be more effective in preventing renal decline, rather than reacting to it.

Pre-dialysis decline of measured glomerular filtration rate but not serum creatinine-based estimated glomerular filtration rate is a risk factor for mortality on dialysis

Background

Monitoring of renal function is important in patients with chronic kidney disease progressing towards end-stage renal failure, both for timing the start of renal replacement therapy and for determining the prognosis on dialysis. Thus far, studies on associations between estimated glomerular filtration rate (eGFR) measurements in the pre-dialysis stage and mortality on dialysis have shown no or even inverse relations, which may result from the poor validity of serum creatinine-based estimation equations for renal function in pre-dialysis patients. As decline in renal function may be better reflected by the mean of the measured creatinine and urea clearance based on 24-h urine collections (mGFR by C Cr-U ), we hypothesize that in patients with low kidney function, a fast mGFR decline is a risk factor for mortality on dialysis, in contrast to a fast eGFR decline.

Methods

For 197 individuals, included from the multicentre NECOSAD cohort, pre-dialysis annual decline of mGFR and eGFR was estimated with linear regression, and classified according to KDOQI as fast (>4 mL/min/1.73 m 2 /year) or slow (≤4 mL/min/1.73 m 2 /year). Cox regression was used to adjust for potential confounders.

Results

Patients with a fast mGFR decline had an increased risk of mortality on dialysis: crude hazard ratio (HR) 1.84 (95% confidence interval: 1.13-2.98), adjusted HR 1.94 (1.11-3.36). In contrast, no association was found between a fast eGFR decline in the pre-dialysis phase and mortality on dialysis: crude HR 1.20 (0.75-1.89), adjusted HR 1.14 (0.67-1.94).

Conclusions

This study demonstrates the importance of mGFR decline (by C Cr-U ) as opposed to eGFR decline in patients with low kidney function, and gives incentive for repeated mGFR measurements in patients on pre-dialysis care.

Longitudinal change in estimated GFR among CKD patients: A 10-year follow-up study of an integrated kidney disease care program in Taiwan

BACKGROUND

This study examined the progression of chronic kidney disease (CKD) by using average annual decline in estimated GFR (eGFR) and its risk factors in a 10-year follow-up CKD cohort.

METHODS

A prospective, observational cohort study, 4600 individuals fulfilled the definition of CKD, with or without proteinuria, were followed for 10 years. The eGFR was estimated by the MDRD equation. Linear regression was used to estimate participants' annual decline rate in eGFR. We defined subjects with annual eGFR decline rate <1 ml/min/1.73 m2 as non-progression and the decline rate over 3 ml/min/1.73 m2 as rapid progression.

RESULTS

During the follow-up period, 2870 (62.4%) individuals had annual eGFR decline rate greater than 1 ml/min/1.73 m2. The eGFR decline rate was slower in individuals with CKD diagnosed over the age of 60 years than those with onset at a younger age. Comparing to subjects with decline rate <1 ml/min/1.73 m2/year, the odds ratio (OR) of developing rapid CKD progression for diabetes, proteinuria and late onset of CKD was 1.72 (95% CI: 1.48-2.00), 1.89(1.63-2.20) and 0.68 (0.56-0.81), respectively. When the model was adjusted for the latest CKD stage, comparing to those with CKD stage 1, patients with stage 4 and stage 5 have significantly higher risks for rapid progression (OR, 5.17 (2.60-10.25), 19.83 (10.05-39.10), respectively). However, such risk was not observed among patients with the latest CKD stage 2 and 3. The risk for incident ESRD was 17% higher for each 1 ml/min/1.73 m2 increasing in annual decline rate.

CONCLUSIONS

Not everyone with CKD develops ESRD after a 10-year follow-up. Absolute annual eGFR decline rate can help clinicians to better predict the progression of CKD. Individuals with renal function decline rate over 3 ml/min/1.73 m2/year require intensive CKD care.

Association between Monocyte Count and Risk of Incident CKD and Progression to ESRD

BACKGROUND AND OBJECTIVES

Experimental evidence suggests a role for monocytes in the biology of kidney disease progression; however, whether monocyte count is associated with risk of incident CKD, CKD progression, and ESRD has not been examined in large epidemiologic studies.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

We built a longitudinal observational cohort of 1,594,700 United States veterans with at least one eGFR during fiscal year 2004 (date of last eGFR during this period designated time zero) and no prior history of ESRD, dialysis, or kidney transplant. Cohort participants were followed until September 30, 2013 or death. Monocyte count closest to and before time zero was categorized in quartiles: quartile 1, >0.00 to ≤0.40 thousand cells per cubic millimeter (k/cmm); quartile 2, >0.40 to ≤0.55 k/cmm; quartile 3, >0.55 to ≤0.70 k/cmm; and quartile 4, >0.70 k/cmm. Survival models were built to examine the association between monocyte count and risk of incident eGFR<60 ml/min per 1.73 m2, risk of incident CKD, and risk of CKD progression defined as doubling of serum creatinine, eGFR decline ≥30%, or the composite outcome of ESRD, dialysis, or renal transplantation.

RESULTS

Over a median follow-up of 9.2 years (interquartile range, 8.3-9.4); in adjusted survival models, there was a graded association between monocyte counts and risk of renal outcomes. Compared with quartile 1, quartile 4 was associated with higher risk of incident eGFR<60 ml/min per 1.73 m2 (hazard ratio, 1.13; 95% confidence interval, 1.12 to 1.14) and risk of incident CKD (hazard ratio, 1.15; 95% confidence interval, 1.13 to 1.16). Quartile 4 was associated with higher risk of doubling of serum creatinine (hazard ratio, 1.22; 95% confidence interval, 1.20 to 1.24), ≥30% eGFR decline (hazard ratio, 1.18; 95% confidence interval, 1.17 to 1.19), and the composite renal end point (hazard ratio, 1.19; 95% confidence interval, 1.16 to 1.22). Cubic spline analyses of the relationship between monocyte count levels and renal outcomes showed a linear relationship, in which risk was higher with higher monocyte count. Results were robust to changes in sensitivity analyses.

CONCLUSIONS

Our results show a significant association between higher monocyte count and risks of incident CKD and CKD progression to ESRD.

High resolution computed tomography pattern of usual interstitial pneumonia in rheumatoid arthritis-associated interstitial lung disease: Relationship to survival

PURPOSE

Interstitial lung disease is a common extra-articular manifestation of rheumatoid arthritis (RA-ILD) and is associated with significant morbidity and mortality. However, limited data exist regarding predictors of mortality. We sought to examine the prognostic value of the high-resolution computed tomography (HRCT) patterns in patients with RA-ILD.

MATERIALS AND METHODS

RA-ILD patients with HRCT patterns of usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP) were identified among a longitudinal cohort of individuals evaluated at National Jewish Health. A total of 158 subjects were included in the study. For each subject, the earliest available HRCT was reviewed independently by two expert thoracic radiologists blinded to clinical data. HRCT patterns were classified as demonstrating definite UIP, possible UIP, or NSIP. Kaplan-Meier curves were generated and survival was compared among the three patterns using a log rank test for trend.

RESULTS

One hundred subjects (63%) had HRCT findings classified as definite UIP, 23 (15%) as possible UIP and 35 (22%) as NSIP. No difference in survival was seen between subjects with definite UIP versus those with possible UIP. The combined group of subjects with either definite- or possible UIP had significantly worse survival than those with NSIP (log-rank p = 0.03).

CONCLUSIONS

In patients with RA-ILD, patients with either definite UIP or possible UIP have equally poor survival when compared to those with an NSIP pattern.

Severe Decline of Estimated Glomerular Filtration Rate Associates with Progressive Cognitive Deterioration in the Elderly: A Community-Based Cohort Study

Cognitive dysfunction is closely related to aging and chronic kidney disease (CKD). However, the association between renal function changes and the risk of developing cognitive impairment has not been elucidated. This longitudinal cohort study was to determine the influence of annual percentage change in estimated glomerular filtration rate (eGFR) on subsequent cognitive deterioration or death of the elderly within the community. A total of 33,654 elders with eGFR measurements were extracted from the Taipei City Elderly Health Examination Database. The Short Portable Mental Status Questionnaire was used to assess their cognitive progression at least twice during follow-up visits. Multivariable Cox regression models were used to estimate the hazard ratio (HR) for cognitive deterioration or all-cause mortality with the percentage change in eGFR. During a median follow-up of 5.4 years, the participants with severe decline in eGFR (>20% per year) had an increased risk of cognitive deterioration (HR, 1.33; 95% confidence interval [CI], 1.08-1.72) and the composite outcome (HR, 1.17; 95% CI, 1.03-1.35) when compared with those who had stable eGFR. Severe eGFR decline could be a possible predictor for cognitive deterioration or death among the elderly. Early detection of severe eGFR decline is a critical issue and needs clinical attentions.

Is Kidney Transplantation a Better State of CKD? Impact on Diagnosis and Management

Patients with CKD are at increased risk for cardiovascular events, hospitalizations, and mortality. Kidney transplantation (KTx) is the preferred treatment for end-stage kidney disease. Although comorbidities including anemia and bone and mineral disease improve or are even halted after KTx, kidney transplant recipients carry higher cardiovascular mortality risk than the general population, as well as an increased risk of infections, malignancies, fractures, and obesity. When comparing CKD with CKD after transplantation (CKD-T), the rate of decline of estimated glomerular filtration rate (eGFR) is significantly lower in CKD-T. Higher rate of decline of eGFR has been associated with increased risk of mortality. However, due to the significant increased risk of mortality due to cardiovascular events, infections, and malignancies, many kidney transplant recipients may not benefit of decline in the rate of eGFR. Patients with CKD-T are a unique subset of patients with multiple traditional and transplant-specific risk factors. Proper management and appropriate preventive health measures may improve long-term patient and allograft survival in patients with CKD-T.

Geographic Variation and US County Characteristics Associated With Rapid Kidney Function Decline

Introduction

Geographic variation in the prevalence of chronic kidney disease and incidence of end-stage renal disease has been previously reported. However, the geographic epidemiology of rapid estimated glomerular filtration rate (eGFR) decline has not been examined.

Methods

We built a longitudinal cohort of 2,107,570 US veterans to characterize the spatial epidemiology of and examine the associations between US county characteristics and rapid eGFR decline.

Results

There were 169,029 (8.02%) with rapid eGFR decline (defined as eGFR slope < –5 ml/min per 1.73 m²/year). The prevalence of rapid eGFR decline adjusted for age, race, gender, diabetes, and hypertension varied by county from 4.10%–6.72% in the lowest prevalence quintile to 8.41%–22.04% in the highest prevalence quintile (P for heterogeneity < 0.001). Examination of adjusted prevalence showed substantial geographic variation in those with and without diabetes and those with and without hypertension (P for heterogeneity < 0.001). Cohort participants had higher odds of rapid eGFR decline when living in counties with unfavorable characteristics in domains including health outcomes (odds ratio [OR] = 1.15; confidence interval [CI] = 1.09–1.22), health behaviors (OR = 1.08; CI = 1.03–1.13), clinical care (OR = 1.11; CI = 1.06–1.16), socioeconomic conditions (OR = 1.15; CI = 1.09–1.22), and physical environment (OR = 1.15; CI = 1.01–1.20); living in counties with high percentage of minorities and immigrants was associated with rapid eGFR decline (OR = 1.25; CI = 1.20–1.31). Spatial analyses suggest the presence of cluster of counties with high prevalence of rapid eGFR decline.

Discussion

Our findings show substantial geographic variation in rapid eGFR decline among US veterans; the variation persists in analyses stratified by diabetes and hypertension status; results show associations between US county characteristics in domains capturing health, socioeconomic, environmental, and diversity conditions, and rapid eGFR decline.

Renal Dysfunction in Post-Stroke Patients

BACKGROUND

The presence of chronic kidney disease (CKD) is an indicator of a worse long-term prognosis in patients with ischemic stroke (IS). Unfortunately, not much is known about renal function in the population of post-IS subjects. The aim of our study was to assess the prevalence of renal damage and impaired renal function (IRF) in the population of post-IS subjects.

METHODS

This prospective analysis concerned 352 consecutive post-IS survivors hospitalized in Pomeranian stroke centers (Poland) in 2009. In this group estimated glomerular filtration rate (eGFR) according to MDRD (modification of diet in renal diseases) and CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formulas and urine albumin/creatinine ratio (ACR) were determined.

RESULTS

Among survivors decreased eGFR (<60 mL/min./1.73m2 according to MDRD or CKD-EPI) or ACR≥30mg/g were detected in 40.38% (23.07% Men, 55.32% Women; P<0.01). The highest prevalence of IRF was noted in post-IS subjects with atheromatic and lacunar IS. In multivariate analysis the ACR≥30mg/g was predicted by older age, diabetes mellitus (DM) and physical disability (modified Rankin scale 3-5 pts.). The association with reduced eGFR was proved for sex (female), DM and physical disability.

CONCLUSIONS

CKD is a frequently occurring problem in the group of post-IS subjects, especially after lacunar and atheromatic IS. Post-IS patients, mainly the elderly women, with physical disability and diabetes mellitus, should be regularly screened for CKD. This could reduce the risk of further cardiovascular events and delay the progression of IRF.

Past Decline Versus Current eGFR and Subsequent Mortality Risk

A single determination of eGFR associates with subsequent mortality risk. Prior decline in eGFR indicates loss of kidney function, but the relationship to mortality risk is uncertain. We conducted an individual-level meta-analysis of the risk of mortality associated with antecedent eGFR slope, adjusting for established risk factors, including last eGFR, among 1.2 million subjects from 12 CKD and 22 other cohorts within the CKD Prognosis Consortium. Over a 3-year antecedent period, 12% of participants in the CKD cohorts and 11% in the other cohorts had an eGFR slope <-5 ml/min per 1.73 m(2) per year, whereas 7% and 4% had a slope >5 ml/min per 1.73 m(2) per year, respectively. Compared with a slope of 0 ml/min per 1.73 m(2) per year, a slope of -6 ml/min per 1.73 m(2) per year associated with adjusted hazard ratios for all-cause mortality of 1.25 (95% confidence interval [95% CI], 1.09 to 1.44) among CKD cohorts and 1.15 (95% CI, 1.01 to 1.31) among other cohorts during a follow-up of 3.2 years. A slope of +6 ml/min per 1.73 m(2) per year also associated with higher all-cause mortality risk, with adjusted hazard ratios of 1.58 (95% CI, 1.29 to 1.95) among CKD cohorts and 1.43 (95% CI, 1.11 to 1.84) among other cohorts. Results were similar for cardiovascular and noncardiovascular causes of death and stronger for longer antecedent periods (3 versus <3 years). We conclude that prior decline or rise in eGFR associates with an increased risk of mortality, independent of current eGFR.

Progression of Kidney Disease in Indigenous Australians: The eGFR Follow-up Study

BACKGROUND AND OBJECTIVES

Indigenous Australians experience a heavy burden of CKD. To address this burden, the eGFR Follow-Up Study recruited and followed an Indigenous Australian cohort from regions of Australia with the greatest ESRD burden. We sought to better understand factors contributing to the progression of kidney disease. Specific objectives were to assess rates of progression of eGFR in Indigenous Australians with and without CKD and identify factors associated with a decline in eGFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This observational longitudinal study of Indigenous Australian adults was conducted in >20 sites. The baseline cohort was recruited from community and primary care clinic sites across five strata of health, diabetes status, and kidney function. Participants were then invited to follow up at 2-4 years; if unavailable, vital status, progression to RRT, and serum creatinine were obtained from medical records. Primary outcomes were annual eGFR change and combined renal outcome (first of ≥30% eGFR decline with follow-up eGFR<60 ml/min per 1.73 m(2), progression to RRT, or renal death).

RESULTS

Participants (n=550) were followed for a median of 3.0 years. Baseline and follow-up eGFR (geometric mean [95% confidence interval], 83.9 (80.7 to 87.3) and 70.1 (65.9 to 74.5) ml/min per 1.73 m(2), respectively. Overall mean annual eGFR change was -3.1 (-3.6 to -2.5) ml/min per 1.73 m(2). Stratified by baseline eGFR (≥90, 60-89, <60 ml/min per 1.73 m(2)), annual eGFR changes were -3.0 (-3.6 to -2.4), -1.9 (-3.3 to -0.5), and -5.0 (-6.5 to -3.6) ml/min per 1.73 m(2). Across baseline eGFR categories, annual eGFR decline was greatest among adults with baseline albumin-to-creatinine ratio (ACR) >265 mg/g (30 mg/mmol). Baseline determinants of the combined renal outcome (experienced by 66 participants) were higher urine ACR, diabetes, lower measured GFR, and higher C-reactive protein.

CONCLUSIONS

The observed eGFR decline was three times higher than described in nonindigenous populations. ACR was confirmed as a powerful predictor for eGFR decline across diverse geographic regions.

Does Nucleos(t)ide Analogues Treatment Affect Renal Function in Chronic Hepatitis B Patients Who Have Already Decreased eGFR? A Longitudinal Study

This study aimed to assess the renal function in chronic hepatitis B (CHB) patients who received nucleos(t)ide analogues (NAs) therapy using estimated glomerular filtration rate (eGFR) titer. We performed a longitudinal observational study of 37 tenofovir-, 42 telbivudine-, and 62 entecavir-naïve CHB patients, who had impaired renal function (eGFR, 90-30 ml/min/1.73m2) without history of diabetes, hypertension, and chemotherapy. Calculation and evaluation of eGFR was performed with the Modification of Diet in Renal Disease, Chronic Kidney Disease Epidemiology Collaboration, and Cockcroft-Gault formula at pretreatment, at baseline, and after the 1st and 2nd year of treatment. The eGFR was significantly increased in patients given telbivudine or entecavir (p = 0.003 and p = 0.012, respectively), but the eGFR was decreased in patients given tenofovir (p = 0.001) after 2 years of treatment. Of all patients, eGFR was stable one year prior to treatment. If we analyzed the renal function by change of chronic kidney disease (CKD) category with a change of 25% of eGFR, the proportion of uncertain drop (drop in CKD category with <25% decrease in eGFR) and certain drop (drop in CKD category with ≧25% decrease in eGFR) in tenofovir group was smaller (5.4%) than those of telbivudine (12.9%) or entecavir (6.5%). Furthermore, telbivudine had the lowest stable rate (76.2%), the highest certain rise rate (9.5%), and certain drop rate (7.1%) compared to the other groups (p = 0.049). In conclusion, in NAs-naïve CHB patients with impaired renal function, telbivudine and entecavir resulted in a significant increase in eGFR while tenofovir resulted in a significant decrease after a 2-year treatment. Interestingly, TDF had the lowest proportion of patients reclassified to certain and uncertain drop groups; in contrast, LdT had a higher proportion in both raise and drop groups. The outcomes of this renal effect remain to be determined.

Estimated GFR Trajectories of People Entering CKD Stage 4 and Subsequent Kidney Disease Outcomes and Mortality

BACKGROUND

Estimated glomerular filtration rate (eGFR) trajectories of people entering chronic kidney disease (CKD) stage 4 and their associations with subsequent kidney disease outcomes or death are not known.

STUDY DESIGN

Longitudinal observational cohort study.

SETTING & PARTICIPANTS

26,246 patients in the Veterans Affairs Healthcare System who entered CKD stage 4 in fiscal year 2008 followed up until October 2013.

FACTORS

5-year eGFR trajectories, demographic and health characteristics.

OUTCOMES

Composite kidney disease outcome of kidney failure, dialysis therapy or transplantation, and death.

RESULTS

Latent class group modeling and functional characterization suggest the presence of 3 distinct trajectory classes: class 1 (72%), consistent slow decline with absolute eGFR change of -2.45 (IQR, -3.89 to -1.16) mL/min/1.73m(2) per year; class 2 (18%), consistent fast decline and eGFR change of -8.60 (IQR, -11.29 to -6.66) mL/min/1.73m(2) per year; and class 3 (10%), early nondecline and late fast decline with eGFR change of -0.4mL/min/1.73m(2) per year in years 1 to 3 and -7.98 and -21.36mL/min/1.73m(2) per year in years 4 and 5, respectively. During 4.34 years of follow-up, 9,809 (37%) patients had the composite kidney disease outcome and 14,550 (55%) patients died. Compared to the referent group (trajectory class 1), HRs for 1-year risk for composite kidney disease outcome for trajectory classes 2 and 3 were 1.13 (95% CI, 1.05-1.22) and 0.67 (95% CI, 0.59-0.75), whereas HRs for 1-year risk for death for classes 2 and 3 were 1.17 (95% CI, 1.10-1.28) and 1.29 (95% CI, 1.18-1.42), respectively. The 1-year risk for composite kidney disease outcome was 32% and was 42% more likely than the risk for death in trajectory classes 1 and 2, respectively, whereas the risk for death was 67% more likely than the risk for composite kidney disease outcome in trajectory class 3.

LIMITATIONS

Inclusion criteria and mostly male participants limit generalizability of study results.

CONCLUSIONS

We characterized 3 different eGFR trajectory classes of people entering CKD stage 4. Our results suggest that the pattern of eGFR trajectory informs the risk for kidney disease outcomes and death.

Renal Function Trajectories in Patients with Prior Improved eGFR Slopes and Risk of Death

Background

Multiple prior studies demonstrated that patients with early Chronic Kidney Disease (CKD) and positive estimated Glomerular Filtration Rate (eGFR) slopes experience increased risk of death. We sought to characterize patients with positive eGFR slopes, examine the renal function trajectory that follows the time period where positive slope is observed, and examine the association between different trajectories and risk of death.

Methods and Findings

We built a cohort of 204,132 United States veterans with early CKD stage 3; eGFR slopes were defined based on Bayesian mixed-effects models using outpatient eGFR measurements between October 1999 and September 2004; to build renal function trajectories, patients were followed longitudinally thereafter (from October 2004) until September 2013. There were 41,410 (20.29%) patients with positive eGFR slope and they exhibited increased risk of death compared to patients with stable eGFR slope (HR = 1.33, CI:1.31–1.35). There was an inverse graded association between severity of albuminuria and the odds of positive eGFR slope (OR = 0.94, CI:0.90–0.98, and OR = 0.76, CI:0.69–0.84 for microalbuminuria and albuminuria; respectively). Following the time period where positive eGFR slope is observed, we characterized 4 trajectory phenotypes: high eGFR intercept and positive trajectory (HIPT) (12.42%), intermediate intercept and mild negative trajectory (IIMNT) (60.04%), low intercept and fast negative trajectory (LIFNT)(23.33%), and high intercept and fast negative trajectory (HIFNT) (4.20%). Compared to IIMNT (reference group), HIPT is associated with younger age, dementia, HIV, chronic lung disease, peripheral artery disease, weight loss, and inversely associated with albuminuria; LIFNT and HIFNT were associated with diabetes, hypertension, cardiovascular disease, peripheral artery disease, and albuminuria. The risk of death at 9 years was lowest in IIMNT (HR = 1.12, CI:1.09–1.14), highest in HIPT (HR = 1.71, CI:1.63–1.79), and intermediate in LIFNT (HR = 1.36, CI:1.32–1.40) and HIFNT (HR = 1.56, CI:1.45–1.68).

Conclusions

Our results demonstrate that patients with positive eGFR slopes, when followed over longer period of time, follow 4 distinct trajectory phenotypes that have distinct demographic and clinical correlates and are differentially associated with risk of death.

Association of Slopes of Estimated Glomerular Filtration Rate With Post-End-Stage Renal Disease Mortality in Patients With Advanced Chronic Kidney Disease Transitioning to Dialysis

OBJECTIVE

To investigate the association of estimated glomerular filtration rate (eGFR) slopes before dialysis initiation with cause-specific mortality after dialysis initiation.

PATIENTS AND METHODS

In this retrospective cohort study of 18,874 US veterans who had transitioned to dialysis from October 1, 2007, through September 30, 2011, we examined the association of pre-end-stage renal disease (ESRD) eGFR slopes with all-cause, cardiovascular, and infection-related mortality during the post-ESRD period over a median follow-up of 2.0 years (interquartile range, 1.1-3.2 years). Associations were examined using Cox models with adjustment for potential confounders.

RESULTS

Before the 18,874 patients transitioned to dialysis, 4485 (23.8%), 5633 (29.8%), and 7942 (42.1%) experienced fast, moderate, and slow eGFR decline, respectively, and 814 (4.3%) had increasing eGFR (defined as eGFR slopes of less than -10, -10 to less than -5, -5 to <0, and ≥0 mL/min per 1.73 m(2) per year). During the study period, a total of 9744 all-cause, 2702 cardiovascular, and 604 infection-related deaths were observed. Compared with patients with slow eGFR decline, those with moderate and fast eGFR decline had a higher risk of all-cause mortality (adjusted hazard ratio [HR], 1.06; 95% CI, 1.00-1.11; and HR, 1.11; 95% CI, 1.04-1.18, respectively) and cardiovascular mortality (HR, 1.11; 95% CI, 1.01-1.23 and HR, 1.13; 95% CI, 1.00-1.27, respectively). In contrast, increasing eGFR was only associated with higher infection-related mortality (HR, 1.49; 95% CI, 1.03-2.17).

CONCLUSION

Rapid eGFR decline is associated with higher all-cause and cardiovascular mortality, and increasing eGFR is associated with higher infection-related mortality among incident dialysis cases.

Low levels of high-density lipoprotein cholesterol increase the risk of incident kidney disease and its progression

Available experimental evidence suggests a role for high-density lipoprotein cholesterol (HDL-C) in incident chronic kidney disease (CKD) and its progression. However, clinical studies are inconsistent. We therefore built a cohort of 1,943,682 male US veterans and used survival models to examine the association between HDL-C and risks of incident CKD or CKD progression (doubling of serum creatinine, eGFR decline of 30% or more), or a composite outcome of ESRD, dialysis, or renal transplantation. Models were adjusted for demographics, comorbid conditions, eGFR, body mass index, lipid parameters, and statin use over a median follow-up of 9 years. Compared to those with HDL-C of 40 mg/dl or more, low HDL-C (under 30 mg/dl) was associated with increased risk of incident eGFR under 60 ml/min/1.73 m(2) (hazard ratio: 1.18; confidence interval: 1.17-1.19) and risk of incident CKD (1.20; 1.18-1.22). Adjusted models demonstrate an association between low HDL-C and doubling of serum creatinine (1.14; 1.12-1.15), eGFR decline of 30% or more (1.13; 1.12-1.14), and the composite renal end point (1.08; 1.06-1.11). Cubic spline analyses of the relationship between HDL-C levels and renal outcomes showed a U-shaped relationship, where risk was increased in lowest and highest deciles of HDL-C. Thus, a significant association exists between low HDL-C levels and risks of incident CKD and CKD progression. Further studies are needed to explain the increased risk of adverse renal outcomes in patients with high HDL-C.

Renal function trajectory over time and adverse clinical outcomes

The growing burden of chronic kidney disease (CKD), with its associated morbidity and mortality, is recognized as a major public health problem globally and causing substantial load on health care systems. The current framework for the definition and staging of CKD, based on eGFR levels or presence of kidney damage, is useful for clinical classification of patients, but identifies a huge number of people as having CKD which is too many to target for intervention. The ability to identify a subset of patients, at high risk for adverse outcomes, would be useful to inform clinical management. The current staging system applies static definitions of kidney function that fail to capture the dynamic nature of the kidney disease over time. Now-a-days, it is possible to capture multiple measurements of different laboratory test results for an individual including eGFR values. A new possibility for identifying individuals at higher risk of adverse outcomes is being explored through assessment and consideration of the rate of change in kidney function over time, and this approach will be feasible in the current context of digitalization of health record keeping system. On the basis of the existing evidence, this paper summarizes important findings that support the concept of dynamic changes in kidney function over time, and discusses how the magnitude of these changes affect the future adverse outcomes of kidney disease, particularly the End Stage Renal Disease (ESRD), CVD and mortality.

Past Decline Versus Current eGFR and Subsequent ESRD Risk

eGFR is a robust predictor of ESRD risk. However, the prognostic information gained from the past trajectory (slope) beyond that of the current eGFR is unclear. We examined 22 cohorts to determine the association of past slopes and current eGFR level with subsequent ESRD. We modeled hazard ratios as a spline function of slopes, adjusting for demographic variables, eGFR, and comorbidities. We used random effects meta-analyses to combine results across studies stratified by cohort type. We calculated the absolute risk of ESRD at 5 years after the last eGFR using the weighted average baseline risk. Overall, 1,080,223 participants experienced 5163 ESRD events during a mean follow-up of 2.0 years. In CKD cohorts, a slope of -6 versus 0 ml/min per 1.73 m(2) per year over the previous 3 years (a decline of 18 ml/min per 1.73 m(2) versus no decline) associated with an adjusted hazard ratio of ESRD of 2.28 (95% confidence interval, 1.88 to 2.76). In contrast, a current eGFR of 30 versus 50 ml/min per 1.73 m(2) (a difference of 20 ml/min per 1.73 m(2)) associated with an adjusted hazard ratio of 19.9 (95% confidence interval, 13.6 to 29.1). Past decline contributed more to the absolute risk of ESRD at lower than higher levels of current eGFR. In conclusion, during a follow-up of 2 years, current eGFR associates more strongly with future ESRD risk than the magnitude of past eGFR decline, but both contribute substantially to the risk of ESRD, especially at eGFR<30 ml/min per 1.73 m(2).

Arteriovenous fistula creation may slow estimated glomerular filtration rate trajectory

BACKGROUND

We practice the timely placement of an arteriovenous fistula (AVF) in patients facing chronic hemodialysis. We have anecdotally observed after AVF creation that there appears to be a slowing of the decline in kidney function as measured by the estimated glomerular filtration rate (eGFR). There are physiologically plausible explanations as to how an AVF might alter kidney function, but this clinical observation has been attributed to improved compliance and/or other practices. The present retrospective observational analysis was performed to assess the possibility that a successfully created AVF could be associated with the slowing of the eGFR trajectory.

METHODS

We identified 123 patients between 2005 and 2010 with at least two eGFR determinations for 2 years before and up to 2 years after AVF creation. Inclusion eligibility was that the fistula was maturing by the nephrologists' initial post-creation examination. Termination events were death, starting dialysis or transplantation. Each subject served as their own control for the pre- and post-AVF-creation eGFR measurements.

RESULTS

Subjects' median age was 68 years and 56% were diabetic. The rate of change of the eGFR for the 2 years prior to AVF creation was -5.9 mL/min/year (95% CI: -5.3, -6.5) and after AVF creation -0.5 mL/min/year (95% CI: -1.1, 0.1) (interaction (P < 0.001).

CONCLUSIONS

A functioning AVF may be associated with a slowing of the eGFR decline. Agreeing to timely AVF creation selects patients in an otherwise typical population and other confounders have not yet been eliminated. To do so a thorough prospective observational study is indicated.

Stage 5-CKD under nephrology care: to dialyze or not to dialyze, that is the question

Appropriate timing of starting chronic dialysis in patients with advanced chronic kidney disease (CKD) under nephrology care still is undefined. We systematically reviewed the most recent studies that have compared outcomes of stage 5-CKD under conservative versus substitutive treatment. Eleven studies, most in elderly patients, were identified. Results indicate no advantage of dialysis over conservative management in terms of survival, hospitalization or quality of life. This information is integrated with a case report on a middle-aged CKD patient followed in our clinic who has remained for 15 years in stage 5 despite severe disease. The patient is a diabetic woman who underwent right nephrectomy in 1994 because of renal tuberculosis. In 1999, she commenced regular nephrology care in our clinic and, since 2000, when she was 53 years old, her estimated glomerular filtration rate (eGFR) has been ≤15 ml/min/1.73 m(2). Over the last decade, despite, several episodes of acute kidney injury and placement of permanent percutaneous nephrostomy in 2001, renal function has remained remarkably stable, though severely impaired (eGFR 7.7-5.6 ml/min/1.73 m(2)). Our systematic analysis of the literature and this case report highlight the need for further studies, not limited exclusively to elderly patients, to verify the efficacy of non-dialysis treatment in stage 5-CKD patients. Meanwhile, nephrologists may consider that their intervention can safely prolong for several years the dialysis-free condition in ESRD independently of age.

A mouse model of Townes-Brocks syndrome expressing a truncated mutant Sall1 protein is protected from acute kidney injury

It has been postulated that developmental pathways are reutilized during repair and regeneration after injury, but functional analysis of many genes required for kidney formation has not been performed in the adult organ. Mutations in SALL1 cause Townes-Brocks syndrome (TBS) and nonsyndromic congenital anomalies of the kidney and urinary tract, both of which lead to childhood kidney failure. Sall1 is a transcriptional regulator that is expressed in renal progenitor cells and developing nephrons in the embryo. However, its role in the adult kidney has not been investigated. Using a mouse model of TBS ( Sall1 TBS), we investigated the role of Sall1 in response to acute kidney injury. Our studies revealed that Sall1 is expressed in terminally differentiated renal epithelia, including the S3 segment of the proximal tubule, in the mature kidney. Sall1 TBS mice exhibited significant protection from ischemia-reperfusion injury and aristolochic acid-induced nephrotoxicity. This protection from acute injury is seen despite the presence of slowly progressive chronic kidney disease in Sall1 TBS mice. Mice containing null alleles of Sall1 are not protected from acute kidney injury, indicating that expression of a truncated mutant protein from the Sall1 TBS allele, while causative of congenital anomalies, protects the adult kidney from injury. Our studies further revealed that basal levels of the preconditioning factor heme oxygenase-1 are elevated in Sall1 TBS kidneys, suggesting a mechanism for the relative resistance to injury in this model. Together, these studies establish a functional role for Sall1 in the response of the adult kidney to acute injury.

On the rationale of population screening for chronic kidney disease: a public health perspective

Unlike opportunistic screening, population screening is accompanied by stringent quality control measures and careful programme monitoring. Sufficient evidence for benefit together with acceptable harms and costs to society are needed before launching a programme. A screening programme is a complex process organized at the population level involving multiple actors of the health care system that should ideally be supervised by public health authorities and evaluated by an independent and trustful body. Chronic kidney disease is defined by reduced glomerular filtration rate and/or presence of kidney damage for at least three months. Chronic kidney disease is divided into 5 stages with stages 1 to 3 being usually asymptomatic. Chronic kidney disease affects one in ten adults worldwide and its prevalence sharply increases with age. Kidney function is measured using serum creatinine-based, and/or cystatin C-based, equations. Markers of renal function show high intra-individual and inter-laboratory variabilities, highlighting the need for standardized procedures. There is also large inter-individual variability in age-related kidney function decline. Despite these limitations, chronic kidney disease, as currently defined, has been consistently associated with high cardiovascular morbidity and mortality and high risk of end-stage renal disease. Major modifiable risk factors for chronic kidney disease are diabetes, hypertension, obesity and cardiovascular disease. Several treatment options, ranging from antihypertensive and lipid-lowering treatments to dietary measures, reduce all-cause mortality and/or end-stage renal disease in patients with stages 1-3 chronic kidney disease. So far, no randomized controlled trial comparing outcomes with and without population screening for stages 1-3 chronic kidney disease has been published. Population screening for stages 1-3 chronic kidney disease is currently not recommended because of insufficient evidence for benefit. Given the current and future burden attributable to chronic kidney disease, randomized controlled trials exploring benefits and harms of population screening are clearly needed to prioritize resource allocations.

Epidemiology of CKD Regression in Patients under Nephrology Care

Chronic Kidney Disease (CKD) regression is considered as an infrequent renal outcome, limited to early stages, and associated with higher mortality. However, prevalence, prognosis and the clinical correlates of CKD regression remain undefined in the setting of nephrology care. This is a multicenter prospective study in 1418 patients with established CKD (eGFR: 60–15 ml/min/1.73m²) under nephrology care in 47 outpatient clinics in Italy from a least one year. We defined CKD regressors as a ΔGFR ≥0 ml/min/1.73 m²/year. ΔGFR was estimated as the absolute difference between eGFR measured at baseline and at follow up visit after 18–24 months, respectively. Outcomes were End Stage Renal Disease (ESRD) and overall-causes Mortality.391 patients (27.6%) were identified as regressors as they showed an eGFR increase between the baseline visit in the renal clinic and the follow up visit. In multivariate regression analyses the regressor status was not associated with CKD stage. Low proteinuria was the main factor associated with CKD regression, accounting per se for 48% of the likelihood of this outcome. Lower systolic blood pressure, higher BMI and absence of autosomal polycystic disease (PKD) were additional predictors of CKD regression. In regressors, ESRD risk was 72% lower (HR: 0.28; 95% CI 0.14–0.57; p<0.0001) while mortality risk did not differ from that in non-regressors (HR: 1.16; 95% CI 0.73–1.83; p = 0.540). Spline models showed that the reduction of ESRD risk associated with positive ΔGFR was attenuated in advanced CKD stage. CKD regression occurs in about one-fourth patients receiving renal care in nephrology units and correlates with low proteinuria, BP and the absence of PKD. This condition portends better renal prognosis, mostly in earlier CKD stages, with no excess risk for mortality.

Rate of Kidney Function Decline and Risk of Hospitalizations in Stage 3A CKD

BACKGROUND AND OBJECTIVES

Risk of hospitalizations is increased in patients with CKD. We sought to examine the association between rate of kidney function decline and risk of hospitalization in a cohort of patients with early CKD.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

We built a cohort of 247,888 United States veterans who had at least one eGFR measurement between October 1999 and September 2003 and an additional eGFR between October 2003 and September 2004. We selected patients whose initial eGFR was between 45 and 59 ml/min per 1.73 m2. Rate of eGFR change (in milliliters per minute per 1.73 m2 per year) was categorized as no decline (>0), mild (0 to -1, and served as the referent group), moderate (-1 to -5), or severe (>-5) eGFR decline. We built survival models to examine the association between the rate of kidney function decline and the risk of hospitalization and readmission and linear regression to estimate length of hospital stay.

RESULTS

Over a median observation of 9 years (interquartile range, 5.28-9.00), patients with moderate and severe eGFR decline exhibited a higher risk of hospitalizations (hazard ratio [HR], 1.22; 95% confidence interval [95% CI], 1.19 to 1.26; and HR, 1.33; 95% CI, 1.28 to 1.39, respectively). Among patients with moderate and severe eGFR decline, the association between the rate of decline and the risk of hospitalizations was more pronounced with an increased number of hospitalizations (P<0.01). Patients with moderate and severe eGFR decline had a higher risk of readmission (HR, 1.19; 95% CI, 1.13 to 1.26; and HR, 1.53; 95% CI, 1.43 to 1.63, respectively). Among patients with severe eGFR decline, the association between the rate of kidney function decline and the risk of readmission was stronger with an increased number of readmissions (P<0.01). Patients with moderate and severe eGFR decline experienced an additional length of stay of 1.40 (95% CI, 0.88 to 1.92) and 5.00 days per year (95% CI, 4.34 to 5.66), respectively.

CONCLUSIONS

The rate of kidney function decline is associated with a higher risk of hospitalizations, readmissions, and prolonged length of hospital stay.

Longitudinal Study of the Decline in Renal Function in Healthy Subjects

BACKGROUND

Chronic kidney disease is an important concern in preventive medicine, but the rate of decline in renal function in healthy population is not well defined. The purpose of this study was to determine reference values for the estimated glomerular filtration rate (eGFR) and rate of decline of eGFR in healthy subjects and to evaluate factors associated with this decline using a large cohort in Japan.

METHODS

Retrospective cross-sectional and longitudinal studies were performed with healthy subjects aged ≥18 years old who received a medical checkup. Reference values for eGFR were obtained using a nonparametric method and those for decline of eGFR were calculated by mixed model analysis. Relationships of eGFR decline rate with baseline variables were examined using a linear least-squares method.

RESULTS

In the cross-sectional study, reference values for eGFR were obtained by gender and age in 72,521 healthy subjects. The mean (±SD) eGFR was 83.7±14.7 ml/min/1.73 m2. In the longitudinal study, reference values for eGFR decline rate were obtained by gender, age, and renal stage in 45,586 healthy subjects. In the same renal stage, there was little difference in the rate of decline regardless of age. The decline in eGFR depended on the renal stage and was strongly related to baseline eGFR, with a faster decline with a higher baseline eGFR and a slower decline with a lower baseline eGFR. The mean (±SD) eGFR decline rate was ‒1.07±0.42 ml/min/1.73 m2/year (‒1.29±0.41%/year) in subjects with a mean eGFR of 81.5±11.6 ml/min/1.73 m2.

CONCLUSIONS

The present study clarified for the first time the reference values for the rate of eGFR decline stratified by gender, age, and renal stage in healthy subjects. The rate of eGFR decline depended mainly on baseline eGFR, but not on age, with a slower decline with a lower baseline eGFR.

Independent Role of Underlying Kidney Disease on Renal Prognosis of Patients with Chronic Kidney Disease under Nephrology Care

Primary kidney disease is suggested to affect renal prognosis of CKD patients; however, whether nephrology care modifies this association is unknown. We studied patients with CKD stage I-IV treated in a renal clinic and with established diagnosis of CKD cause to evaluate whether the risk of renal event (composite of end-stage renal disease and eGFR decline ≥40%) linked to the specific diagnosis is modified by the achievement or maintenance in the first year of nephrology care of therapeutic goals for hypertension (BP ≤130/80 mmHg in patients with proteinuria ≥150 mg/24h and/or diabetes and ≤140/90 in those with proteinuria <150 mg/24h and without diabetes) anemia (hemoglobin, Hb ≥11 g/dL), and proteinuria (≤0.5 g/24h). Survival analysis started after first year of nephrology care. We studied 729 patients (age 64±15 y; males 59.1%; diabetes 34.7%; cardiovascular disease (CVD) 44.9%; hypertensive nephropathy, HTN 53.8%; glomerulonephritis, GN 17.3%; diabetic nephropathy, DN 15.9%; tubule-interstitial nephropathy, TIN 9.5%; polycystic kidney disease, PKD 3.6%). During first year of Nephrology care, therapy was overall intensified in most patients and prevalence of main therapeutic goals generally improved. During subsequent follow up (median 3.3 years, IQR 1.9-5.1), 163 renal events occurred. Cox analysis disclosed a higher risk for PKD (Hazard Ratio 5.46, 95% Confidence Intervals 2.28–10.6) and DN (1.28,2.99–3.05), versus HTN (reference), independently of age, gender, CVD, BMI, eGFR or CKD stage, use of RAS inhibitors and achievement or maintenance in the first year of nephrology care of each of the three main therapeutic goals. No interaction was found on the risk of CKD progression between diagnostic categories and month-12 eGFR (P=0.737), as with control of BP (P=0.374), Hb (P=0.248) or proteinuria (P=0.590). Therefore, in CKD patients under nephrology care, diagnosis of kidney disease should be considered in conjunction with the main risk factors to refine renal risk stratification.

Annual decline in estimated glomerular filtration rate is a risk factor for cardiovascular events independent of proteinuria

AIMS

Chronic kidney disease is a risk factor of the development of cardiovascular disease (CVD). However, it is not clear whether decline of glomerular filtration rate (GFR), not reduced GFR, is a risk factor for the incidence of CVD independent of proteinuria.

METHODS

By using a population-based 521 123 person-years longitudinal cohort receiving annual health checkups from 2008 to 2010, we examined whether the annual decline of estimated GFR is a risk factor for CVD development independent of proteinuria.

RESULTS

During the follow-up period, there were 12 041 newly developed CVD events, comprising 4426 stroke events and/or 8298 cardiac events. As expected, both reduced estimated GFR and proteinuria were risk factors for the development of CVD in our study population. Moreover, annual decline of estimated GFR was a significant and independent risk factor for the incidence of CVD (HR [95% CI], 1.23 [1.18-1.28] in males or 1.14 [1.10-1.18] in females for -10% per year) with covariant adjustment for proteinuria and reduced estimated GFR.

CONCLUSION

Annual decline of GFR is an independent risk factor for CVD. Serial measurement of both creatinine and proteinuria would be better to predict the incidence of CVD in the general population.

Change in Multiple Filtration Markers and Subsequent Risk of Cardiovascular Disease and Mortality

BACKGROUND AND OBJECTIVES

Kidney disease progression, assessed by change in eGFR on the basis of creatinine, is an independent risk factor for cardiovascular disease and death. This study aimed to evaluate whether changes in multiple filtration markers, individually and combined, were associated with cardiovascular disease and death.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Creatinine, cystatin C, and β2-microglobulin were measured among 9716 Atherosclerosis Risk in Communities Study participants in 1990-1992 and 1996-1998. Percentage change in three filtration markers (eGFR on the basis of creatinine, eGFR on the basis of cystatin C, and 1/β2-microglobulin) individually and the average of percentage change across all three filtration markers were calculated. Cardiovascular events and deaths were ascertained from 1996 to 2011. Cox regression models were adjusted for established risk factors for cardiovascular disease and mortality and first measurement of eGFR on the basis of creatinine.

RESULTS

During a median follow-up of 14 years, there were 1922 cardiovascular events and 2285 deaths from any cause. Decline of >30% in each filtration marker was significantly associated with higher risk of mortality compared with stable kidney function (-9.9% to +9.9% change in the filtration marker) with hazard ratios (95% confidence intervals) of 1.91 (1.67 to 2.18) for eGFR on the basis of creatinine, 2.29 (1.99 to 2.63) for eGFR on the basis of cystatin C, and 2.48 (2.15 to 2.86) for 1/β2-microglobulin, with similar associations for cardiovascular disease. An average decline of >30% across the three markers was strongly associated with higher risk of all-cause mortality (hazard ratio, 2.82; 95% confidence interval, 2.42 to 3.29).

CONCLUSIONS

Kidney disease progression was assessed using >30% decline in eGFR on the basis of creatinine, eGFR on the basis of cystatin C, and 1/β2-microglobulin and average decline of >30% across the three filtration markers is strongly associated with risk of cardiovascular disease and death.

Plasma neutrophil gelatinase-associated lipocalin and kidney function decline and kidney disease-related clinical events in older women

BACKGROUND

It is still unclear whether serum neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of renal tubular injury, is a prognostic marker for the progression of chronic kidney disease (CKD) in the general population.

METHODS

A prospective-cohort study of 1,245 women aged ≥70 from the general population. Associations between plasma NGAL and change in 5-year estimated glomerular filtration rate (eGFR), rapid renal decline and 10-year risk of acute or chronic renal disease-related hospitalisations and/or mortality were examined.

RESULTS

Compared to women with above-median plasma NGAL of 76.5 ng/l, women with below-median plasma NGAL had a 9.3% reduction in eGFR over a 5-year period. Among women with above-median plasma NGAL, there was over a 1.7-fold increased risk of rapid renal decline (eGFR decline of >3 ml/min/year) (adjusted odds ratio 1.76, 95% CI 1.003, 3.102, p = 0.049). Compared to women with baseline eGFR of <60 ml/min/1.73 m(2), women with above-median plasma NGAL experienced over a 2.5-fold increased risk of renal disease events at 10 years (hazard ratio 2.55, 95% CI 1.13, 5.78, p = 0.025) after adjustment of age, hypertension and diabetes. Addition of plasma NGAL in participants with eGFR of <60 ml/min/1.73 m(2) significantly improved the accuracy in predicting the 10-year risk of renal disease events (adjusted area-under-curve receiver operator characteristics without and with NGAL 0.64 and 0.71, respectively; p = 0.027) and reclassified 13% of women who experienced renal disease events into the higher risk categories (p = 0.03).

CONCLUSION

Plasma NGAL is of modest clinical utility in predicting the renal function decline and risk of renal disease-related clinical events, particularly those with mild to moderate CKD.

Variability in estimated glomerular filtration rate values is a risk factor in chronic kidney disease progression among patients with diabetes

Background

It is unknown whether variability of estimated Glomerular Filtration Rate (eGFR) is a risk factor for dialysis or death in patients with chronic kidney disease (CKD). This study aimed to evaluate variability of estimated Glomerular Filtration Rate (eGFR) as a risk factor for dialysis or death to facilitate optimum care among high risk patients.

Methods

A longitudinal retrospective cohort study of 70,598 Veterans Health Administration veteran patients with diabetes and CKD (stage 3–4) in 2000 with up to 5 years of follow-up. VHA and Medicare files were linked to derive study variables. We used Cox proportional hazards models to evaluate association between time to initial dialysis/death and key independent variables: time-varying eGFR variability (measured by standard deviation (SD)) and eGFR means and slopes while adjusting for prior hospitalizations, and comorbidities.

Results

There were 76.7% older than 65 years, 97.5% men, and 81.9% Whites. Patients were largely in early stage 3 (61.2%), followed by late stage 3 (28.9%), and stage 4 (9.9%); 29.1%, 46.8%, and 73.3%, respectively, died or had dialysis during the follow-up. eGFR SDs (median: 5.8, 5.1, and 4.0 ml/min/1.73 m² ) and means (median: 54.1, 41.0, 27.2 ml/min/1.73 m²) from all two-year moving intervals decreased as CKD advanced; eGFR variability (relative to the mean) increased when CKD progressed (median coefficient of variation: 10.9, 12.8, and 15.4). Cox regressions revealed that one unit increase in a patient’s standard deviation of eGFRs from prior two years was significantly associated with about 7% increase in risk of dialysis/death in the current year, similarly in all three CKD stages. This was after adjusting for concurrent means and slopes of eGFRs, demographics, prior hospitalization, and comorbidities. For example, the hazard of dialysis/death increased by 7.2% (hazard ratio:1.072; 95% CI = 1.067, 1.080) in early stage 3.

Conclusion

eGFR variability was independently associated with elevated risk of dialysis/death even after controlling for eGFR means and slopes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0025-5) contains supplementary material, which is available to authorized users.

Prevalence of renal impairment and use of nephrotoxic agents among patients with bone metastases from solid tumors in the United States

The renal status of patients with bone metastases secondary to solid tumors and their treatment with nephrotoxic agents is not well characterized. This retrospective study analyzed electronic medical records data from US-based oncology clinics to identify adult (age ≥18) solid tumor patients with first bone metastasis diagnosis and ≥1 serum creatinine recorded between January 1, 2009 and December 31, 2013. Patients with multiple myeloma, multiple primary tumor types, acute renal failure, and/or end-stage renal disease were excluded. Using the Chronic Kidney Disease Epidemiology Collaboration formula, we determined the prevalence of renal impairment (RI: single estimated glomerular filtration rate [eGFR] value <60 mL/min per 1.73 m(2) ) and chronic kidney disease (CKD: ≥2 eGFR values <60, at least 90 days apart). We also examined the use of intravenous bisphosphonates (IV BP) and other nephrotoxic agents. Approximately half of the 11,809 patients were female. Breast (34%) and lung (28%) tumors were the most common. At bone metastasis diagnosis, mean age was 67 years and 24% of patients exhibited RI. The 5-year prevalence was 43% for RI and 71% for CKD among RI patients. Nearly half (46%) of CKD patients received IV BP in the 12 months following their confirming eGFR and 13% of these patients received at least one other nephrotoxic agent during that period. This is the first US-based study to examine the prevalence of RI among patients with bone metastases from solid tumors. RI is common at bone metastases diagnosis, and a substantial proportion of patients develop RI or CKD as their disease progresses. Whenever possible, treatments that are potentially less damaging for the kidney should be considered for patients with or predisposed to RI.

Risks of rapid decline renal function in patients with type 2 diabetes

Progressive rising population of diabetes and related nephropathy, namely, diabetic kidney disease and associated end stage renal disease has become a major global public health issue. Results of observational studies indicate that most diabetic kidney disease progresses over decades; however, certain diabetes patients display a rapid decline in renal function, which may lead to renal failure within months. Although the definition of rapid renal function decline remained speculative, in general, it is defined by the decrease of estimated glomerular filtration rate (eGFR) in absolute rate of loss or percent change. Based on the Kidney Disease: Improving Global Outcomes 2012 clinical practice guidelines, a rapid decline in renal function is defined as a sustained decline in eGFR of > 5 mL/min per 1.73 m(2) per year. It has been reported that potential factors contributing to a rapid decline in renal function include ethnic/genetic and demographic causes, smoking habits, increased glycated hemoglobin levels, obesity, albuminuria, anemia, low serum magnesium levels, high serum phosphate levels, vitamin D deficiency, elevated systolic blood pressure, pulse pressure, brachial-ankle pulse wave velocity values, retinopathy, and cardiac autonomic neuropathy. This article reviews current literatures in this area and provides insight on the early detection of diabetic subjects who are at risk of a rapid decline in renal function in order to develop a more aggressive approach to renal and cardiovascular protection.

Genome-wide association study reveals a polymorphism in the podocyte receptor RANK for the decline of renal function in coronary patients

Impaired kidney function is a significant health problem and a major concern in clinical routine and is routinely determined by decreased glomerular filtration rate (GFR). In contrast to single assessment of a patients' kidney function providing only limited information on patients' health, serial measurements of GFR clearly improves the validity of diagnosis. The decline of kidney function has recently been reported to be predictive for mortality and vascular events in coronary patients. However, it has not been investigated for genetic association in GWA studies. This study investigates for the first time the association of cardiometabolic polymorphisms with the decline of estimated GFR during a 4 year follow up in 583 coronary patients, using the Cardio-Metabo Chip. We revealed a suggestive association with 3 polymorphisms, surpassing genome-wide significance (p = 4.0 e-7). The top hit rs17069906 (p = 5.6 e-10) is located within the genomic region of RANK, recently demonstrated to be an important player in the adaptive recovery response in podocytes and suggested as a promising therapeutic target in glomerular diseases.