Background.

Patients with acute kidney injury (AKI) requiring initiation of renal replacement therapy (RRT) have poor short- and long-term outcomes, including the development of dialysis dependence. Currently, little is known about what factors may predict renal recovery in this population.

Methods.

We conducted a single-center, retrospective analysis of 170 hospitalized adult patients with AKI attributed to acute tubular necrosis who required inpatient initiation of RRT. Data collection included patient characteristics, laboratory data, details of hospital course and degree of fluid overload at RRT initiation. The primary outcome was recovery of renal function to dialysis independence.

Results.

Within 1 year of RRT initiation, 35.9% (61/170) of patients reached the primary end point of renal recovery. The median (interquartile range) duration of RRT was 11 (3–33) days and 83.6% (51/61) recovered prior to hospital discharge. Recovering patients had significantly less fluid overload at the time of RRT initiation compared to non-recovering patients (3.5 versus 9.3%, P = 0.004). In multivariate Cox proportional hazard regression analysis, a rise in percent fluid overload at dialysis initiation remained a significant negative predictor of renal recovery (hazard ratio 0.97, 95% confidence interval 0.95–1.00, P = 0.024).

Conclusions.

In patients with AKI, a higher degree of fluid overload at RRT initiation predicts worse renal recovery at 1 year. Clinical trials are needed to determine whether interventions targeting fluid overload may improve patient and renal outcomes.

Background

Little is known regarding chronic kidney disease (CKD) in Hispanics. We compared baseline characteristics of Hispanic participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC (H-CRIC) Studies with non-Hispanic CRIC participants.

Study Design

Cross-sectional analysis

Setting and Participants

Participants were aged 21–74 years with CKD using age-based glomerular filtration rate (eGFR) at enrollment into the CRIC/H-CRIC Studies. H-CRIC included Hispanics recruited at the University of Illinois from 2005–2008 while CRIC included Hispanics and non-Hispanics recruited at seven clinical centers from 2003–2007.

Factor

Race/ethnicity

Outcomes

Blood pressure, angiotensin-converting enzyme (ACE) inhibitor/angiotensin receptor blocker (ARB) use, CKD-associated complications

Measurements

Demographic characteristics, laboratory data, blood pressure, and medications were assessed using standard techniques and protocols

Results

Among H-CRIC/ CRIC participants, 497 were Hispanic, 1650 non-Hispanic Black, and 1638 non-Hispanic White. Low income and educational attainment were nearly twice as prevalent in Hispanics compared with non-Hispanics (p<0.01). Hispanics had self-reported diabetes (67%) more frequently than non-Hispanic Blacks (51%) and Whites (40%) (p<0.01). Blood pressure > 130/80 mmHg was more common in Hispanics (62%) compared with Blacks (57%) and Whites (35%) (p<0.05), and abnormalities in hematologic, metabolic, and bone metabolism parameters were more prevalent in Hispanics (p<0.05), even after stratifying by entry eGFR. Hispanics had the lowest receipt of ACE inhibitor/ARB among high-risk subgroups, including participants with diabetes, proteinuria, and blood pressure > 130/80 mmHg. Mean eGFR (ml/min/m2) was lower in Hispanics (39.6) than in Blacks (43.7) and Whites (46.2), while median proteinuria was higher in Hispanics (0.72 g/d) than in Blacks (0.24 g/d) and Whites (0.12 g/d) (p<0.01).

Limitations

Generalizability; observed associations limited by residual bias and confounding

Conclusions

Hispanics with CKD in CRIC/H-CRIC Studies are disproportionately burdened with lower socioeconomic status, more frequent diabetes mellitus, less ACE inhibitor/ARB use, worse blood pressure control, and more severe CKD and associated complications than their non-Hispanic counterparts.

Background/Aims

Metabolic syndrome may increase the risk for incident cardiovascular disease (CVD) and all-cause mortality in the general population. It is unclear whether, and to what degree, metabolic syndrome is associated with CVD in chronic kidney disease (CKD). We determined metabolic syndrome prevalence among individuals with a broad spectrum of kidney dysfunction, examining the role of the individual elements of metabolic syndrome and their relationship to prevalent CVD.

Methods

We evaluated four models to compare metabolic syndrome or its components to predict prevalent CVD using prevalence ratios in the Chronic Renal Insufficiency Cohort (CRIC) Study.

Results

Among 3,939 CKD participants, the prevalence of metabolic syndrome was 65% and there was a significant association with prevalent CVD. Metabolic syndrome was more common in diabetics (87.5%) compared with non-diabetics (44.3%). Hypertension was the most prevalent component, and increased triglycerides the least prevalent. Using the bayesian information criterion, we found that the factors defining metabolic syndrome, considered as a single interval-scaled variable, was the best of four models of metabolic syndrome, both for CKD participants overall and for diabetics and non-diabetics separately.

Conclusion

The predictive value of this model for future CVD outcomes will subsequently be validated in longitudinal analyses.

Context

High levels of the phosphate regulating hormone, fibroblast growth factor 23 (FGF23), associate with mortality in patients with end-stage renal disease (ESRD), but little is known about its relationship with adverse outcomes in the much larger population of patients with earlier stages of chronic kidney disease (CKD).

Objective

Evaluate FGF23 as a risk factor for adverse outcomes in patients with CKD.

Design, Setting and Participants

A prospective study of 3,879 participants with CKD stages 2 – 4 who enrolled in the Chronic Renal Insufficiency Cohort between June 2003 and September 2008.

Main Outcome Measures

All-cause mortality and ESRD.

Results

At enrollment, mean estimated glomerular filtration rate (eGFR) was 42.8 ± 13.5 ml/min/1.73m2, and median FGF23 was 145 (interquartile range [IQR] 96 – 239) reference units/ml (RU/ml). During a median follow-up of 3.5 (IQR 2.5 – 4.4) years, 266 participants died (20.3/1000 person-years) and 410 reached ESRD (33.0/1000 person-years). Higher FGF23 levels independently associated with a greater risk of death in adjusted analyses of FGF23 on a continuous scale (hazard ratio [HR] per SD of lnFGF23, 1.5; 95%CI 1.3 – 1.7) or in quartiles (quartile 1, reference; quartile 2, HR 1.3; 95%CI 0.8 – 2.2; quartile 3, HR 2.0; 95%CI 1.2 – 3.3; quartile 4, HR 3.0; 95%CI 1.8 – 5.1). FGF23 was not independently associated with ESRD in adjusted analyses of the entire cohort, however, the effect was modified by eGFR (P for interaction = 0.005), which was the strongest predictor for ESRD. FGF23 independently associated with significantly greater risk of ESRD among participants with eGFR 30 – 44 (HR 1.3 per SD of lnFGF23; 95%CI 1.04 – 1.6) and ≥ 45 (HR 1.7; 95%CI 1.1 – 2.4), but not < 30 ml/min/1.73m2.

Conclusion

Elevated FGF23 is an independent risk factor for ESRD in patients with relatively preserved kidney function and for mortality across the spectrum of CKD.

Chronic kidney disease (CKD) is a public health epidemic that increases risk of death due to cardiovascular disease. Left ventricular hypertrophy (LVH) is an important mechanism of cardiovascular disease in individuals with CKD. Elevated levels of FGF23 have been linked to greater risks of LVH and mortality in patients with CKD, but whether these risks represent causal effects of FGF23 is unknown. Here, we report that elevated FGF23 levels are independently associated with LVH in a large, racially diverse CKD cohort. FGF23 caused pathological hypertrophy of isolated rat cardiomyocytes via FGF receptor–dependent activation of the calcineurin-NFAT signaling pathway, but this effect was independent of klotho, the coreceptor for FGF23 in the kidney and parathyroid glands. Intramyocardial or intravenous injection of FGF23 in wild-type mice resulted in LVH, and klotho-deficient mice demonstrated elevated FGF23 levels and LVH. In an established animal model of CKD, treatment with an FGF–receptor blocker attenuated LVH, although no change in blood pressure was observed. These results unveil a klotho-independent, causal role for FGF23 in the pathogenesis of LVH and suggest that chronically elevated FGF23 levels contribute directly to high rates of LVH and mortality in individuals with CKD.

Background

The epidemiology of atrial fibrillation (AF) has been mainly investigated in patients with end-stage renal disease (ESRD), with limited data on less advanced chronic kidney disease (CKD) stages.

Methods

A total of 3267 adult participants (50% non-Hispanic blacks, 46% females) with CKD from the Chronic Renal Insufficiency Cohort (CRIC) were included in this study. None of the study participants had been on dialysis. Those with self-identified race/ethnicity other than non-Hispanic black or white (N=323) or those without ECG data (N=22) were excluded. AF was ascertained by a 12-lead electrocardiogram (ECG) and self-report. Age- sex- race/ethnicity-specific prevalence rates of AF were estimated and compared between subgroups. Cross sectional associations and correlates with prevalent AF were examined using unadjusted and multivariable adjusted logistic regression analysis.

Results

The mean estimated glomerular filtration rate (GFR) was 43.6 (±13.0) ml/min/1.73 m2. AF was present in 18% of the study population and in more than 25% of those 70 years or older. In multivariable adjusted models, 1-SD increase in age (11 years) [odds ratio (OR) and CI 95%: 1.27 (1.13, 1.43), P<0.0001], female sex [0.80 (0.65, 0.98), P=0.0303], smoking (former vs. never) [1.34 (1.08, 1.66), P= 0.0081], history of heart failure [3.28 (2.47, 4.36), P<0.001], and history of cardiovascular disease [1.94 (1.56, 2.43), P<0.0001] were significantly associated with AF. Race/ethnicity, hypertension, diabetes, body mass index, physical activity, education, high sensitivity C-reactive protein, total cholesterol, and alcohol intake were not significantly associated with AF. An estimated GFR <45 ml/min/1.73 m2 was associated with AF in an unadjusted model [1.35 (1.13–1.62)); P=0.0010)], but not after multivariable adjustment [1.12 (0.92– 1.35), P=0.2710].

Conclusions

Nearly one in five participants in CRIC, a national study of CKD, had evidence for AF at study entry, a prevalence similar to that reported among patients with ESRD and 2–3 times of that reported in the general population. Risk factors for AF in this CKD population do not mirror those reported in the general population.

Objectives

To investigate cognitive impairment in older, ethnically diverse individuals with a broad range of kidney function, to evaluate a spectrum of cognitive domains and to determine whether the relationship between CKD and cognitive function is independent of demographic and clinical factors.

Design

Cross sectional.

Setting

Chronic Renal Insufficiency Cohort Study.

Participants

825 adults ≥55 years with CKD.

Measurements

We estimated glomerular filtration rate (eGFR, ml/min/1.73 m2) using the four-variable Modification of Diet in Renal Disease equation. We compared cognitive scores on six cognitive tests across eGFR strata using linear regression; multivariable logistic regression was used to examine level of CKD and clinically significant cognitive impairment (score ≤1 sd from mean).

Results

Mean age of the participants was 64.9 years, 50% were male and 45% were Black. After multi-variable adjustment, participants with lower eGFR had lower cognitive scores on most cognitive domains (P<0.05). In addition, compared with persons who had mild or moderate CKD (eGFR 45-59), participants with advanced CKD (eGFR <30) were more likely to have clinically significant cognitive impairment on global cognition (adjusted odds ratio [OR] 2.0, 95% CI 1.1-3.9), naming (OR 1.9, 95% CI 1.0-3.3), attention (OR 2.4, 95%CI 1.3-4.5), executive function (OR 2.5, 95%CI 1.9- 4.4) and delayed memory, (OR=1.5, 95%CI 0.9-2.6) but not on category fluency (OR=1.1, 95% CI 0.6-2.0).

Conclusions

Among older adults with CKD, lower level of kidney function was associated with lower cognitive function on most domains. Our results suggest that older patients with advanced CKD should be screened for cognitive impairment.

Steroid-free regimen is increasingly employed in kidney transplant recipients across transplant centers. However, concern remains because of unknown impact of such approach on long-term graft and patient survival. We studied outcomes of steroid-free immunosuppression in a population-based U.S. cohort of kidney transplant recipients.

All adult solitary kidney transplant recipients engrafted between January 1, 2000 and December 31, 2006 was stratified according to whether they were selected for steroid-free or steroid-containing regimen at discharge. Multivariate Cox regression models were used to estimate graft and patient survival. The impact of practice pattern on steroid use at individual transplant centers was analyzed.

Among 95,755 kidney transplant recipients, 17.2 % of them were steroid-free at discharge (n=16,491). Selection for steroid-free regimen was associated with reduced risks for graft failure and death at 1 year (HR 0.78, 95% CI 0.72-0.85, and 0.73, 95% CI 0.65-0.82, respectively, p<0.0001) and 4 years (HR 0.83, 95% CI 0.78-0.87, and 0.76, 95% CI 0.71-0.83, respectively, p<0.0001). This association was mostly observed at individual centers where less than 65% of recipients were discharged on steroid-containing regimen.

De novo steroid-free immunosuppression as currently practiced in the US appears to carry no increased risk of adverse clinical outcomes in the intermediate term.