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1.  Blood pressure and chronic kidney disease progression in a multi-racial cohort: the Multi-Ethnic Study of Atherosclerosis 
Journal of human hypertension  2013;27(7):10.1038/jhh.2013.1.
The relationship between blood pressure (BP) and kidney function among individuals with chronic kidney disease (CKD) remains controversial. This study evaluated the association between BP and estimated glomerular filtration rate (eGFR) decline among adults with nondiabetic stage 3 CKD. The Multi-Ethnic Study of Atherosclerosis participants with an eGFR 30–59 ml min–1 per 1.73 m2 at baseline without diabetes were included. Participants were followed over a 5-year period. Kidney function change was determined by annualizing the change in eGFR using cystatin C, creatinine and a combined equation. Risk factors for progression of CKD (defined as a decrease in annualized eGFR >2.5 ml min–1 per 1.73 m2) were identified using univariate analyses and sequential logistic regression models. There were 220 participants with stage 3 CKD at baseline using cystatin C, 483 participants using creatinine and 381 participants using the combined equation. The median (interquartile range) age of the sample was 74 (68–79) years. The incidence of progression of CKD was 16.8% using cystatin C and 8.9% using creatinine (P = 0.002). Systolic BP >140 mm Hg or diastolic BP >90 mm Hg was significantly associated with progression using a cystatin C-based (odds ratio (OR), 2.49; 95% confidence interval (CI), 1.12–5.52) or the combined equation (OR, 2.07; 95% CI, 1.16–3.69), but not when using creatinine after adjustment for covariates. In conclusion, with the inclusion of cystatin C in the eGFR assessment hypertension was an important predictor of CKD progression in a multi-ethnic cohort with stage 3 CKD.
doi:10.1038/jhh.2013.1
PMCID: PMC3830562  PMID: 23407373
blood pressure; glomerular filtration rate; renal disease; cystatin C; creatinine; ethnicity
2.  Rate of Kidney Function Decline in Older Adults: A Comparison Using Creatinine and Cystatin C 
American Journal of Nephrology  2009;30(3):171-178.
Background/Aims
The aim of this study was to determine the decline in the estimated glomerular filtration rate (eGFR) in elderly persons and to compare estimates based on creatinine and cystatin C.
Methods
In the Cardiovascular Health Study, GFR changes in an elderly cohort were estimated from serum creatinine and cystatin C measured at baseline, year 3 and year 7 in 4,380 participants (age 72 ± 5 years at entry). Outcomes were mean eGFR decline, incident chronic kidney disease (CKD) and rapid decline in eGFR (annual loss >3 ml/min/1.73 m2).
Results
Mean annual eGFR loss as estimated from creatinine was 0.4 ± 3.6 ml/min/1.73 m2, with 16% of the participants experiencing a rapid decline. Mean eGFR loss as estimated from cystatin C was 1.8 ± 2.6, with 25% of the participants experiencing a rapid decline (p < 0.001 for both). Among participants without baseline CKD, incident CKD was detected at year 7 in 10% (n = 263) using creatinine and 19% (n = 544) using cystatin C (p < 0.001). Increasing age was the strongest predictor of rapid decline; adjusted odds ratios were 1.38 (1.16–1.65), 1.62 (1.31–1.99) and 2.96 (2.28–3.84) for participants aged 70–74, 75–79 and 80+ at baseline, compared with those aged 65–69.
Conclusion
In elderly persons, cystatin C estimated substantially larger declines in kidney function than creatinine did. Defining the optimal measurement of kidney function in elderly persons should be a high priority for future research.
doi:10.1159/000212381
PMCID: PMC2820322  PMID: 19349699
Glomerular filtration rate; Creatinine; Cystatin C; Chronic kidney disease
3.  Association of Tenofovir Exposure with Kidney Disease Risk in HIV Infection 
AIDS (London, England)  2012;26(7):867-875.
Objective
Despite widespread highly active antiretroviral therapy use, HIV disease remains associated with increased risk of kidney disease. Whether tenofovir use is associated with higher risk of kidney disease is controversial.
Design
We evaluated the association of cumulative and ever exposure to tenofovir on kidney outcomes in 10,841 HIV-infected patients from the Veterans Health Administration who initiated antiretroviral therapy from 1997-2007.
Methods
Cox proportional hazards and marginal structural models evaluated associations between tenofovir and time to first occurrence of 1) proteinuria (two consecutive urine dipstick measurements ≥30mg/dL), 2) rapid decline in kidney function (≥3ml/min/1.73m2 annual decline), and 3) CKD (estimated glomerular filtration rate <60ml/min/1.73m2).
Results
Median follow-up ranged from 3.9 years (proteinuria) to 5.5 years (CKD), during which 3400 proteinuria, 3078 rapid decline, and 533 CKD events occurred. After multivariable adjustment, each year of exposure to tenofovir was associated with 34% increased risk of proteinuria (95%CI 25-45%, p<0.0001), 11% increased risk of rapid decline (3-18%, p=0.0033), and 33% increased risk of CKD (18-51%; p<0.0001). Pre-existing renal risk factors did not appear to worsen the effects of tenofovir. Other ARVs showed weaker or inconsistent associations with kidney disease events. Among those who discontinued tenofovir use, risk of kidney disease events did not appear to decrease during follow-up.
Conclusions
Tenofovir exposure was independently associated with increased risk for three types of kidney disease events, and did not appear to be reversible. Because subtle kidney function decline affects long-term morbidity and mortality, the balance between efficacy and probable adverse effects requires further study.
doi:10.1097/QAD.0b013e328351f68f
PMCID: PMC3736566  PMID: 22313955
HIV; antiretroviral therapy; kidney disease; tenofovir
4.  Risk factors for chronic kidney disease in a large cohort of HIV-1 infected individuals initiating antiretroviral therapy in routine care 
AIDS (London, England)  2012;26(15):1907-1915.
Objective
To examine long-term effects of antiretroviral therapy (ART) on kidney function, we evaluated the incidence and risk factors for chronic kidney disease (CKD) among ART-naive, HIV-infected adults and compared changes in estimated glomerular filtration rates (eGFR) before and after starting ART.
Methods
Multicenter observational cohort study of patients with at least one serum creatinine measurement before and after initiating ART. Cox proportional hazard models, and marginal structure models examined CKD risk factors; mixed-effects linear models examined eGFR slopes.
Results
Three thousand, three hundred and twenty-nine patients met entry criteria, contributing 10 099 person-years of observation on ART. ART was associated with a significantly slower rate of eGFR decline (from −2.18 to −1.37 ml/min per 1.73 m2 per year; P = 0.02). The incidence of CKD defined by eGFR thresholds of 60, 45 and 30 ml/min per 1.73 m2 was 10.5, 3.4 and 1.6 per 1000 person-years, respectively. In adjusted analyses black race, hepatitis C coinfection, lower time-varying CD4 cell count and higher time-varying viral load on ART were associated with higher CKD risk, and the magnitude of these risks increased with more severe CKD. Tenofovir and a ritonavir-boosted protease inhibitor (rPI) was also associated with higher CKD risk [hazard odds ratio for an eGFR threshold <60 ml/min per 1.73 m2: 3.35 (95% confidence interval (CI) = 1.40–8.02)], which developed in 5.7% of patients after 4 years of exposure to this regimen-type.
Conclusion
ART was associated with reduced CKD risk in association with CD4 cell restoration and plasma viral load suppression, despite an increased CKD risk that was associated with initial regimens that included tenofovir and rPI.
doi:10.1097/QAD.0b013e328357f5ed
PMCID: PMC3531628  PMID: 22824630
antiretroviral therapy; chronic kidney disease; tenofovir
5.  Kidney function is associated with the rate of cognitive decline in the elderly 
Neurology  2009;73(12):920-927.
Objective:
We tested the hypothesis that impaired kidney function in the elderly is associated with a more rapid rate of cognitive decline.
Methods:
Baseline serum was used to calculate estimated glomerular filtration rate (eGFR), using the Modification of Diet in Renal Disease formula, for 886 elderly without dementia participating in the Rush Memory and Aging Project, a prospective, observational cohort study. Kidney function was also dichotomized into impairment or no impairment based on eGFR < or ≥60 mL/min/1.73 m2. Structured cognitive testing was performed at baseline and at annual evaluations, using a battery of 19 cognitive tests summarized into global cognition and 5 cognitive domains.
Results:
In mixed-effects models adjusted for age, sex, and education, a lower eGFR at baseline was associated with a more rapid rate of cognitive decline (estimate 0.0008, SE <0.001, p = 0.017). The increased rate of cognitive decline associated with a 15-mL/min/1.73 m2 lower eGFR at baseline (approximately 1 SD) was similar to the effect of being 3 years older at baseline. Impaired kidney function at baseline was associated with a more rapid rate of cognitive decline (estimate −0.028, SE <0.009, p = 0.003). The increased rate of cognitive decline associated with impaired kidney function at baseline was approximately 75% the effect of ApoE4 allele on the rate of cognitive decline. Baseline kidney function was associated with declines in semantic memory, episodic memory, and working memory but not visuospatial abilities or perceptual speed.
Conclusion:
Impaired kidney function is associated with a more rapid rate of cognitive decline in old age.
GLOSSARY
= Alzheimer disease;
= body mass index;
= creatinine;
= estimated glomerular filtration rate.
doi:10.1212/WNL.0b013e3181b72629
PMCID: PMC2754333  PMID: 19657107
6.  Clinical and Subclinical Cardiovascular Disease and Kidney Function Decline in the Elderly 
Atherosclerosis  2008;204(1):298-303.
Objective
Kidney function decline in elderly persons may be the result of microvascular atherosclerosis. As a proxy for the renovascular system, we evaluated the association of clinical and subclinical cardiovascular disease (CVD) with kidney function decline.
Methods
This study included 4,380 subjects from the Cardiovascular Health Study, a longitudinal, community-based cohort of persons aged ≥ 65 from 4 U.S. communities. Creatinine and cystatin C were measured at baseline, year 3, and year 7; eligible subjects had at least two measures. Creatinine-based estimated glomerular filtration rate (eGFRcreat) was calculated using the MDRD equation. Rapid kidney function decline was defined as an annual eGFR loss >3 mL/min/1.73m2. Predictors of rapid kidney decline included prevalent and subclinical measures of CVD.
Results
Mean decline in eGFRcreat was 0.4 ± 2.6/year; 714 (16%) had rapid progression. In multivariate models adjusted for demographics, cardiovascular risk factors, and inflammation, prevalent stroke (OR, 95% CI; 1.55, 1.16–2.08) and heart failure (OR, 95% CI: 1.80, 1.40–2.31) were independent predictors of rapid kidney decline. Among persons without clinical CV, the subclinical disease measures ankle arm index < 0.9 (OR, 95% CI: 1.67, 1.25–2.24), common carotid intima-media thickness (≥ 1.14mm) (OR, 95% CI: 1.52, 1.12–2.06) and internal carotid intima-media thickness (>1.82mm) (OR, 95% CI: 1.50, 1.12–2.02) had independent associations with rapid kidney function decline. Results were similar using cystatin C.
Conclusion
Clinical atherosclerosis and heart failure and subclinical measures of CVD have independent associations with kidney function decline progression in the elderly, suggesting an underlying role of renal atherosclerosis.
doi:10.1016/j.atherosclerosis.2008.08.016
PMCID: PMC2696894  PMID: 18848325
Cystatin C; kidney disease; atherosclerosis
7.  Rapid Kidney Function Decline and Mortality Risk in Older Adults 
Archives of internal medicine  2008;168(20):2212-2218.
Background
Impaired kidney function is associated with increased mortality risk in older adults. It remains unknown, however, whether longitudinal declines in kidney function are independently associated with increased cardiovascular and all-cause mortality in older adults.
Methods
The Cardiovascular Health Study evaluated a cohort of community-dwelling older adults enrolled from 1989 to 1993 in 4 US communities with follow-up through 2005. Among 4380 participants, the slope of annual decline in estimated glomerular filtration rate (eGFR) was estimated using both serum creatinine (eGFRcreat) and cystatin C (eGFRcys) rates, which were measured at baseline, year 3, and year 7 of follow-up. Rapid decline in eGFR was defined as a loss greater than 3 mL/min/1.73 m2 per year, and cardiovascular and all-cause mortality were assessed over a mean of 9.9 years of follow-up.
Results
Mean (SD) levels of creatinine and cystatin C were 0.93 (0.30) mg/dL and 1.03 (0.25) mg/L, respectively; mean (SD) eGFRcreat and eGFRcys were 79 (23) mL/min/1.73 m2 and 79 (19) mL/min/1.73 m2, respectively. Individuals with rapid decline measured by eGFRcreat (n=714; 16%) had increased risk of cardiovascular (adjusted hazard ratio [AHR], 1.70; 95% confidence interval [CI], 1.40–2.06) and all-cause (AHR, 1.73; 95% CI, 1.54–1.94) mortality. Individuals with rapid decline measured by eGFRcys (n=1083; 25%) also had increased risk of cardiovascular (AHR, 1.53; 95% CI, 1.29–1.80) and all-cause (AHR, 1.53; 95% CI, 1.38–1.69) mortality. The association of rapid decline in eGFR with elevated mortality risk did not differ across subgroups based on baseline kidney function, age, sex, race, or prevalent coronary heart disease.
Conclusion
Rapid decline in eGFR is associated with an increased risk of cardiovascular and all-cause mortality in older adults, independent of baseline eGFR and other demographic variables.
doi:10.1001/archinte.168.20.2212
PMCID: PMC2879064  PMID: 19001197
8.  Association of Pulse Pressure, Arterial Elasticity, and Endothelial Function With Kidney Function Decline Among Adults With Estimated GFR > 60 mL/min/1.73 m2: The Multi-Ethnic Study of Atherosclerosis 
Background
The association of subclinical vascular disease and early declines in kidney function has not been well studied.
Study Design
Prospective cohort study
Setting & Participants
MESA participants with eGFR ≥60 ml/min/1.73m2 with follow-up of 5 years
Predictors
Pulse pressure (pulse pressure), small and large arterial elasticity (SAE, LAE), and flow mediated dilation.
Outcomes
kidney function decline
Measurements
SAE and LAE were measured by pulse contour analysis of the radial artery. Kidney function was measured by serum creatinine- and cystatin C-based eGFR.
Results
Among 4,853 adults, higher pulse pressure and lower SAE and LAE had independent and linear associations with faster rates of kidney function decline. Compared to persons with pulse pressure 40–50mmHg, eGFRSCysC decline was 0.29 (p=0.006), 0.56 (p<0.001), and 0.91 (p<0.001) ml/min/1.73m2/year faster among persons with pulse pressure 50–60, 60–70, and >70mmHg, respectively. Compared to the highest quartile of SAE (most elastic), eGFRSCysC decline was 0.26 (p=0.009), 0.35 (p=0.001), and 0.70 (p<0.001) ml/min/1.73m2/year faster for the second, third and fourth quartiles respectively. For LAE, compared to the highest quartile, eGFRSCysC decline was 0.28 (p=0.004), 0.58 (p<0.001), and 0.83 (p<0.001) ml/min/1.73m2/year faster for each decreasing quartile of LAE. Findings were similar with creatinine-based eGFR. In contrast, among 2,997 adults with flow-mediated dilation and kidney function measures, flow-mediated dilation was not significantly associated with kidney function decline. For every 1-SD greater flow-mediated dilation, eGFRSCysC and eGFRSCr changed by 0.05 ml/min/1.73m2/year (p=0.3) and 0.06 ml/min/1.73m2/year (p=0.04), respectively.
Limitations
We had no direct measure of GFR, in common with nearly all large population based studies.
Conclusions
Higher pulse pressure and lower arterial elasticity, but not flow-mediated dilation, were linearly and independently associated with faster kidney function decline among persons with eGFR ≥60 ml/min/1.73m2. Future studies investigate whether treatments to lower stiffness of large and small arteries may slow the rate of kidney function loss.
doi:10.1053/j.ajkd.2011.08.015
PMCID: PMC3242889  PMID: 22000727
kidney function; arterial elasticity; chronic kidney disease; atherosclerosis
9.  Baseline Predictors of Renal Disease Progression in the African American Study of Hypertension and Kidney Disease 
Journal of the American Society of Nephrology : JASN  2006;17(10):10.1681/ASN.2005101101.
Patients with chronic kidney disease have an increased risk for progression to ESRD. The purpose of this study was to examine factors that predict increased risk for adverse renal outcomes. Cox regression was performed to assess the potential of 38 baseline risk factors to predict the clinical renal composite outcome of 50% or 25-ml/min per 1.73 m2 GFR decline or ESRD among 1094 black patients with hypertensive nephrosclerosis (GFR 20 to 65 ml/min per 1.73 m2). Patients were trial participants who had been randomly assigned to one of two BP goals and to one of three antihypertensive regimens and followed for a range of 3 to 6.4 yr. In unadjusted and adjusted analyses, baseline proteinuria was consistently associated with an increased risk for adverse renal outcomes, even at low levels of proteinuria. The relationship of proteinuria with adverse renal outcomes also was evident in analyses that were stratified by level of GFR, which itself was associated with adverse renal outcomes but only at levels <40 ml/min. Other factors that were significantly associated with increased renal events after adjustment for baseline GFR, age, and gender, both with and without adjustment for baseline proteinuria, included serum creatinine, urea nitrogen, and phosphorus. In black patients with hypertensive nephrosclerosis, increased proteinuria, reduced GFR, and elevated levels of serum creatinine, urea nitrogen and phosphorus were directly associated with adverse clinical renal events. These findings identify a subset of this high-risk population that might benefit from even more aggressive treatment.
doi:10.1681/ASN.2005101101
PMCID: PMC3833081  PMID: 16959828
10.  Clinical Implications of the Change in Glomerular Filtration Rate with Adrenergic Blockers in Patients with Morning Hypertension: The Japan Morning Surge-1 Study 
Background. The aim of this study was to clarify the relationship between the change in estimated glomerular filtration rate (eGFR) and urinary albumin by antihypertensive treatment. Methods. We randomized 611 treated patients with morning hypertension into either an added treatment group, for whom doxazosin was added to the current medication, or a control group, who continued their current medications. We compared the change in eGFR and urinary albumin creatinine ratio (UACR) between the groups. Results. The extent of the reduction in eGFR was significantly greater in the added treatment group than in the control group (−3.83  versus −1.08 mL/min/1.73 m2, P = 0.001). In multivariable analyses, the change in eGFR was positively associated with the change in UACR in the added treatment group (β = 0.20, P = 0.001), but not in the control group (β = −0.002, P = 0.97). When the changes in eGFR were divided by each CKD stage, eGFR was significantly more decreased in stage 1 than in the other stages in the added treatment group (P < 0.001), but no differences were seen in the control group (P = 0.44). Conclusion. The reduction of eGFR could be seen only in the early stage of CKD, and this treatment appeared to have no negative effect on renal function.
doi:10.1155/2013/413469
PMCID: PMC3864142  PMID: 24363933
11.  Progression of Kidney Disease in Moderately Hypercholesterolemic, Hypertensive Patients Randomized to Pravastatin Versus Usual Care: A Report From the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) 
Background
Dyslipidemia is common in patients with chronic kidney disease. The role of statin therapy on the progression of kidney disease is unclear.
Study Design
Prospective randomized clinical trial, post hoc analyses.
Setting and participants
10,060 participants in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) (lipid-lowering component) stratified by baseline eGFR: <60, 60–89, ≥90 mL/min/1.73 m2. Mean follow-up was 4.8 years.
Intervention
Randomized, pravastatin 40 mg/day or usual care.
Outcomes and measurements
Total cholesterol, HDL- and LDL-cholesterol; end stage renal disease (ESRD), estimated glomerular filtration rate (eGFR).
Results
Through year six, total cholesterol declined in the pravastatin (−20.7%) and usual care groups (−11.2%). No significant differences were seen between the groups for rates of ESRD (1.36 vs 1.45/100 patient years, P=0.9), composite endpoints of ESRD and 50% or 25% decline in eGFR, or rate of change of eGFR. Findings were consistent across eGFR strata. In patients with eGFR≥90 mL/min/1.73 m2, the pravastatin arm tended to have a higher eGFR.
Limitations
Proteinuria data unavailable, post hoc analyses, unconfirmed validity of the Modification of Diet in Renal Disease Study equation in normal eGFR range, statin drop-in rate in usual care group with small cholesterol differential between groups.
Conclusions
In hypertensive patients with moderate dyslipidemia and reduced eGFR, pravastatin was not superior to usual care in preventing clinical renal outcomes. This was consistent across the strata of baseline eGFR. However, benefit from statin therapy may depend on degree of cholesterol reduction achieved.
doi:10.1053/j.ajkd.2008.05.027
PMCID: PMC2897819  PMID: 18676075
hyperlipidemia; glomerular filtration rate; pravastatin
12.  Albuminuria, impaired kidney function and cardiovascular outcomes or mortality in the elderly 
Nephrology Dialysis Transplantation  2009;25(5):1560-1567.
Background. Kidney disease is a risk factor for mortality and cardiovascular disease in older adults, but the separate and combined effects of albuminuria and cystatin C, a novel marker of glomerular filtration, are not known.
Methods. We examined associations of these markers with mortality and cardiovascular outcomes during a median follow-up of 8.3 years in 3291 older adults in the Cardiovascular Health Study. Kidney disease was assessed using urinary albumin/creatinine ratio (ACR), cystatin C and Modification of Diet in Renal Disease estimated glomerular filtration rate (eGFR). We defined subgroups based on presence of microalbuminuria (MA, ACR > 30 mg/g) and categories of normal kidney function (cystatin C < 1.0 mg/L and eGFR > 60 mL/min/1.73 m2); preclinical kidney disease (cystatin C level > 1.0 mg/l but eGFR > 60 mL/min/1.73 m2); and chronic kidney disease (CKD) (eGFR < 60 mL/min/1.73 m2). Cox proportional hazards models were used to examine associations between these six subgroups and all-cause or cardiovascular mortality, myocardial infarction and heart failure.
Results. One thousand one hundred fifty (34.9%) had normal kidney function (12.2% with MA), 1518 (46.1%) had preclinical kidney disease (17.9% with MA) and 622 (18.9%) had CKD (47% with MA). After adjustment, the presence of either preclinical kidney disease or MA was associated with an over 50% increase in mortality risk; the presence of both was associated with a 2.4-fold mortality risk. Those with CKD and MA were at highest risk, with a nearly 4-fold mortality risk.
Conclusion. Elevated cystatin C and albuminuria are common, identify different subsets of the older population, and are independent, graded risk factors for cardiovascular disease and mortality.
doi:10.1093/ndt/gfp646
PMCID: PMC3307251  PMID: 20008829
albuminuria; aging; cardiovascular diseases; kidney function; mortality
13.  Associations of Urinary Levels of Kidney Injury Molecule-1 (KIM-1) and Neutrophil Gelatinase-Associated Lipocalin (NGAL) With Kidney Function Decline in the Multi-Ethnic Study of Atherosclerosis (MESA) 
Background
Whether elevations of urinary biomarkers of tubular injury (urine neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1)) are associated with future risk of kidney disease has not been investigated.
Study Design
1:1 nested case-control study
Setting & Participants
686 participants in the Multi-Ethnic Study of Atherosclerosis (MESA).
Predictor
NGAL and KIM-1 were measured at baseline and expressed as log-transformed continuous variables and categorized into deciles.
Outcomes
Kidney function was estimated by cystatin C using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. Incident CKD Stage 3 was defined as eGFR <60 ml/min/1.73m2 and a eGFR decline >1 ml/min/1.73m2 per year, and rapid kidney function decline (RKFD) was defined as decline of ≥3 ml/min/1.73m2 per year.
Measurements
Cases were defined as persons with eGFR >60 ml/min/1.73m2 who subsequently developed incident CKD Stage 3 and/or had RKFD by MESA year 5 visit. Controls were matched for age, gender, race, diabetes, and baseline eGFR. We adjusted for age, hypertension and presence of albuminuria (ACR ≥30 mg/g).
Results
Of the 343 cases, 145 had incident CKD Stage 3, 141 had RKFD and 57 had both. Mean eGFR for controls was 81 (±10) ml/min/1.73m2 at baseline and 80 (±10) at follow-up, compared with 82 (±13) and 58 (±10) for cases. Each doubling of KIM-1 (pg/ml) was associated with an OR of 1.15 (95% CI, 1.02-1.29) for incident CKD Stage 3 and/or RKFD. Compared to the lowest 90%, the highest decile of KIM-1 was associated with an OR of 2.02 (95% CI, 1.15-3.56) for the outcome; these associations were independent of albuminuria. NGAL levels (ng/ml) were not associated with incident CKD Stage 3 and/or RKFD (OR, 1.04; 95% CI, 0.99-1.10). Results were similar when KIM-1 and NGAL were standardized for urine creatinine.
Limitations
The case-control design limits ability to account for persons who died or were not available for follow-up.
Conclusions
Urinary KIM-1 is associated with future risk of kidney disease independent of albuminuria. Urinary biomarkers of tubular injury are a promising tool for identifying persons at risk for CKD.
doi:10.1053/j.ajkd.2012.05.014
PMCID: PMC3690926  PMID: 22749388
KIM-1; NGAL; kidney function decline
14.  Long-term graft function changes in kidney transplant recipients 
NDT Plus  2010;3(Suppl 2):ii2-ii8.
Background. Monitoring changes in glomerular filtration rate (GFR) is the recommended method for assessing the progression of kidney disease. The aim of this study was to assess the decline of graft function defined by the annualized change in GFR and the factors which affect it.
Methods. Four thousand four hundred and eighty-eight patients, transplanted during the years 1990, 1994, 1998 and 2002 in 34 centres in Spain with allograft survival of at least 1 year, were included in the study. GFR was estimated using the four-variable equation of the Modification of Diet in Renal Diseases (MDRD) study. Linear mixed effects model was applied to determine the relation between the covariates and the annualized change in GFR after transplantation.
Results. The average GFR at 12 months was 51.4 ± 18.9 mL/min/1.73 m2; most patients were in stage 3 of chronic kidney disease classification. The average patient slope, calculated in a linear model with varying-intercept and varying-slope without covariates, was −1.12 ± 0.05 mL/min/year (slope ± standard error). Some variables were related to both the 12-month GFR (intercept) and the slope: recipient gender, hepatitis C virus (HCV) status, estimated GFR (eGFR) at 3 months and proteinuria at 12 months. Some variables were only related to the slope of eGFR: time on dialysis, primary renal disease and immunosuppression. Others affected only the 12-month GFR: donor age, delayed graft function, acute rejection and systolic blood pressure at 12 months. Higher graft function at 3 months had a negative impact on the GFR slope. Cyclosporine-based immunosuppression had a less favourable effect on the rates of change in allograft function.
Conclusions. There was a slow decline in GFR. Poor graft function was not associated with an increased rate of decline of allograft function. Immunosuppression with cyclosporine displayed the worst declining GFR rate.
doi:10.1093/ndtplus/sfq063
PMCID: PMC2875040  PMID: 20508857
glomerular filtration rate; immunosuppression; kidney transplantation
15.  Reduced cystatin C-estimated GFR and increased creatinine-estimated GFR in comparison with iohexol-estimated GFR in a hyperthyroid patient: A case report 
Introduction
Estimation of the glomerular filtration rate (GFR) is essential for the evaluation of patients with kidney disease, and for treating patients with drugs that are eliminated from the circulation by the kidneys. Cystatin C has been shown to be superior to creatinine for estimating GFR in several studies. However, studies showing that thyroid function has an impact on cystatin C have not addressed the question of whether the changes in cystatin C levels are due to changes in GFR or in cystatin C synthesis.
Case presentation
We report an account of a hyperthyroid patient with a discrepancy between the GFR estimates from cystatin C and creatinine. The cystatin C concentration (1.36 mg/L) was higher and gave an estimated GFR which was lower (51 mL/min/1.73 m2), while the creatinine concentration was lower (36 μmol/L) and gave a corresponding creatinine-estimated GFR that was higher (145 mL/min/1.73 m2) than the iohexol-estimated GFR (121 mL/min/1.73 m2) during the hyperthyroid period. After thyroidectomy, the creatinine concentration was 36 μmol/L and creatinine-estimated GFR was calculated as 73 mL/min/1.73 m2, while the cystatin C concentration and cystatin C-calculated GFR was 0.78 mg/L and 114 mL/min/1.73 m2, respectively.
Conclusion
In contrast to creatinine, cystatin C levels rose in the hyperthyroid state as compared to the euthyroid state. The cystatin C-estimated GFR was reduced compared to the iohexol-estimated GFR. This patient case shows that the hyperthyroid-associated changes in cystatin C levels are not due to changes in GFR. Thyroid function should thus be considered when both cystatin C and creatinine are used as markers of kidney function.
doi:10.1186/1752-1947-2-66
PMCID: PMC2268947  PMID: 18307770
16.  Kidney Function and Mortality in Octogenarians: Cardiovascular Health Study All Stars 
OBJECTIVES:
To examine the association between kidney function and all-cause mortality in octogenarians.
DESIGN:
Retrospective analysis of prospectively collected data.
SETTING:
Community.
PARTICIPANTS:
Serum creatinine and cystatin C were measured in 1,053 Cardiovascular Health Study (CHS) All Stars participants.
MEASUREMENTS:
Estimated glomerular filtration rate (eGFR) was determined using the Chronic Kidney Disease Epidemiology Collaboration creatinine (eGFRCR) and cystatin C one-variable (eGFRCYS) equations. The association between quintiles of kidney function and all-cause mortality was analyzed using unadjusted and adjusted Cox proportional hazards models.
RESULTS:
Mean age of the participants was 85, 64% were female, 66% had hypertension, 14% had diabetes mellitus, and 39% had prevalent cardiovascular disease. There were 154 deaths over a median follow-up of 2.6 years. The association between eGFRCR and all-cause mortality was U-shaped. In comparison with the reference quintile (64–75 mL/min per 1.73 m2), the highest (≥75 mL/min per 1.73 m2) and lowest (≤43 mL/min per 1.73 m2) quintiles of eGFRCR were independently associated with mortality (hazard ratio (HR) = 2.49, 95% confidence interval (CI) = 1.36–4.55; HR = 2.28, 95% CI = 1.26–4.10, respectively). The association between eGFRCYS and all-cause mortality was linear in those with eGFRCYS of less than 60 mL/min per 1.73 m2, and in the multivariate analyses, the lowest quintile of eGFRCYS (<52 mL/min per 1.73 m2) was significantly associated with mortality (HR = 2.04, 95% CI = 1.12–3.71) compared with the highest quintile (>0.88 mL/min per 1.73 m2).
CONCLUSION:
Moderate reduction in kidney function is a risk factor for all-cause mortality in octogenarians. The association between eGFRCR and all-cause mortality differed from that observed with eGFRCYS; the relationship was U-shaped for eGFRCR, whereas the risk was primarily present in the lowest quintile for eGFRCYS. J Am Geriatr Soc 2012.
doi:10.1111/j.1532-5415.2012.04046.x
PMCID: PMC3902776  PMID: 22724391
octogenarians; kidney function; mortality
17.  Prediction of mortality and functional decline by changes in eGFR in the very elderly: the Leiden 85-plus study 
BMC Geriatrics  2013;13:61.
Background
The prevalence of chronic kidney disease is high in the elderly, but the effects of a decrease in the eGFR on mortality and functioning are still unclear. The aim of this study was to determine whether the combination of the eGFR and the eGFR slope is a predictor of mortality and functional decline.
Methods
The eGFR (MDRD equation) and the eGFR slope were calculated. The slope was calculated using four annual eGFR measurements taken from 85 to 88 years of age. Mortality and changes in the Mini-Mental State Examination (MMSE), the Geriatric Depression Scale (GDS-15) and the Activities of Daily Living (ADL) scores were analysed as outcomes from 88 years onwards.
Results
378 persons aged 88 years participating to the Leiden 85 plus study, an observational prospective cohort study in the general population, were included. A combined analysis of the baseline eGFR and the eGFR slope showed that an eGFR of >60 ml/min combined with an eGFR decrease of ≥ 3 ml/min/year and an eGFR of <60 ml/min combined with an of eGFR decrease ≥5 ml/min/year were independent predictors of increased mortality. The baseline eGFR, the eGFR slope and a combination of both factors did not predict changes in the MMSE, GDS or ADL scores between 88 and 90 years.
Conclusion
The combination of the eGFR and the eGFR decrease allows the identification of subgroups of very elderly with increased mortality risks and of subgroups of very elderly with an eGFR of <60 ml/min without an increased risk of mortality.
doi:10.1186/1471-2318-13-61
PMCID: PMC3689623  PMID: 23777458
Very elderly; Population-based study; eGFR; Decrease in eGFR; Mortality; Functional decline
18.  Detection of Renal Function Decline in Patients with Diabetes and Normal or Elevated GFR by Serial Measurements of Serum Cystatin C Concentration: Results of a 4-Year Follow-Up Study 
Research on early renal function decline in diabetes is hampered by lack of simple tools for detecting trends (particularly systematic decreases) in renal function over time when GFR is normal or elevated. This study sought to assess how well serum cystatin C meets that need. Thirty participants with type 2 diabetes in the Diabetic Renal Disease Study met these three eligibility criteria: GFR >20 ml/min per 1.73 m2 at baseline (based on cold iothalamate clearance), 4 yr of follow-up, and yearly measurements of iothalamate clearance and serum cystatin C. With the use of linear regression, each individual’s trend in renal function over time, expressed as annual percentage change in iothalamate clearance, was determined. Serum cystatin C in mg/L was transformed to its reciprocal (100/cystatin C), and linear regression was used to determine each individual’s trend over time, expressed as annual percentage change. In paired comparisons of 100/cystatin C with iothalamate clearance at each examination, the two measures were numerically similar. More important, the trends in 100/cystatin C and iothalamate clearance were strongly correlated (Spearman r = 0.77). All 20 participants with negative trends in iothalamate clearance (declining renal function) also had negative trends for 100/cystatin C. Results were discordant for only three participants. In contrast, the trends for three commonly used creatinine-based estimates of GFR compared poorly with trends in iothalamate clearance (Spearman r < 0.35). Serial measures of serum cystatin C accurately detect trends in renal function in patients with normal or elevated GFR and provide means for studying early renal function decline in diabetes.
doi:10.1681/ASN.2004100854
PMCID: PMC2429917  PMID: 15788478
19.  Association of kidney function with inflammatory and procoagulant markers in a diverse cohort: A cross-sectional analysis from the Multi-Ethnic Study of Atherosclerosis (MESA) 
BMC Nephrology  2008;9:9.
Background
Prior studies using creatinine-based estimated glomerular filtration rate (eGFR) have found limited associations between kidney function and markers of inflammation. Using eGFR and cystatin C, a novel marker of kidney function, the authors investigated the association of kidney function with multiple biomarkers in a diverse cohort.
Methods
The Multi-Ethnic Study of Atherosclerosis consists of 6,814 participants of white, African-American, Hispanic, and Chinese descent, enrolled from 2000–2002 from six U.S. communities. Measurements at the enrollment visit included serum creatinine, cystatin C, and six inflammatory and procoagulant biomarkers. Creatinine-based eGFR was estimated using the four-variable Modification of Diet in Renal Disease equation, and chronic kidney disease was defined by an eGFR < 60 mL/min/1.73 m2.
Results
Adjusted partial correlations between cystatin C and all biomarkers were statistically significant: C-reactive protein (r = 0.08), interleukin-6 (r = 0.16), tumor necrosis factor-α soluble receptor 1 (TNF-αR1; r = 0.75), intercellular adhesion molecule-1 (r = 0.21), fibrinogen (r = 0.14), and factor VIII (r = 0.11; two-sided p < 0.01 for all). In participants without chronic kidney disease, higher creatinine-based eGFR was associated only with higher TNF-αR1 levels.
Conclusion
In a cohort characterized by ethnic diversity, cystatin C was directly associated with multiple procoagulant and inflammatory markers. Creatinine-based eGFR had similar associations with these biomarkers among subjects with chronic kidney disease.
doi:10.1186/1471-2369-9-9
PMCID: PMC2533297  PMID: 18681974
20.  Comparison of Measured GFR, Serum Creatinine, Cystatin C, and Beta-Trace Protein to Predict ESRD in African Americans With Hypertensive CKD 
Background
Identification of persons with chronic kidney disease (CKD) who are at highest risk to progress to end stage renal disease (ESRD) is necessary to reduce the burden of kidney failure. The relative utility of traditional markers of kidney function, including estimated glomerular filtration rate (GFR) and serum creatinine, and emerging markers of kidney function, including cystatin C and beta-trace protein (BTP), to predict ESRD and mortality has yet to be established.
Study Design
Randomized clinical trial followed by an observational cohort study.
Setting & Participants
865 African American individuals with hypertensive CKD enrolled in a clinical trial of two levels of blood pressure control and three different antihypertensive drugs as initial therapy and subsequently followed by an observational cohort study.
Predictors
Quintile of measured GFR (mGFR) by iothalamate clearance, serum creatinine, serum creatinine-based estimated GFR (eGFRSCr), cystatin C, and BTP.
Outcomes and Measurements
Incidence of ESRD and mortality.
Results
A total of 246 participants reached ESRD over a median follow-up of 102 months. The incidence rate of ESRD was higher with higher quintiles of each marker. The association between higher BTP and ESRD was stronger than those for the other markers, including mGFR. All the markers remained significantly associated with ESRD after adjustment for mGFR and relevant covariates (all p<0.05), with BTP retaining the strongest association (HR for highest versus lowest quintile, 5.7; 95% CI, 2.2-14.9). Associations with the combined endpoint of ESRD or mortality (n=390) were weaker, but remained significant for cystatin C (p=0.05) and BTP (p=0.004).
Limitations
The ability of these markers to predict ESRD and mortality in other racial and ethnic groups and among individuals with CKD due to other causes is unknown.
Conclusions
Plasma BTP and cystatin C may be useful adjuncts to serum creatinine and mGFR in evaluating risk for progression of kidney disease.
doi:10.1053/j.ajkd.2011.07.018
PMCID: PMC3221777  PMID: 21944667
End-stage renal disease; beta trace protein; cystatin C; serum creatinine; iothalamate glomerular filtration rate
21.  Prevalence of kidney disease in anaemia differs by GFR-estimating method: The Third National Health and Nutrition Examination Survey (1988–94) 
Nephrology Dialysis Transplantation  2010;25(8):2542-2548.
Background. Anaemia worsens as kidney function declines. Both conditions are associated with increased mortality. Serum cystatin C is purportedly a more sensitive marker of kidney disease and a better predictor of mortality than serum creatinine. However, studies suggest that extrarenal factors also influence cystatin C levels.
Methods. We determined whether estimates of glomerular filtration rate [estimated glomerular filtration rate (eGFR)] based on serum cystatin C alone or in combination with serum creatinine were superior to those based on serum creatinine in recognizing impaired kidney function in the setting of anaemia in a sub-sample of the Third National Health and Nutrition Examination Survey of the USA consisting of 6734 participants, 20 years or older.
Results. The prevalence of moderate to severe kidney disease (eGFR 15–59 mL/min/1.73 m2) among anaemic persons was 15–16% when based on serum creatinine alone (eGFRSCR) or combined with cystatin C (eGFRSCR + CYSC); this estimate increased to nearly 25% when kidney function was estimated by cystatin C (eGFRCYSC). The adjusted odds ratios of kidney disease in anaemic versus non-anaemic persons were slightly higher with eGFRCYSC than eGFRSCR and eGFRSCR + CYSC in younger adults [odds ratio (OR) = 5.22, 95% confidence interval (CI): 2.23, 12.17], women (OR = 5.34, 95% CI: 2.36, 12.06) and those with elevated C-reactive protein (CRP) (OR = 7.36, 95% CI: 1.98–27.36).
Conclusions. Impaired kidney function was common in individuals with anaemia. Among anaemic individuals, the prevalence estimate for kidney disease was notably higher when kidney function was estimated by cystatin C alone compared with the estimations by serum creatinine alone or in combination with serum cystatin C. eGFRCYSC may be particularly helpful in identifying kidney disease in the setting of anaemia among younger persons, women and those with elevated CRP. Regardless of which renal biomarker is used, our study suggests that an evaluation for underlying kidney disease should be considered in the standard workup of anaemia.
doi:10.1093/ndt/gfq040
PMCID: PMC2910334  PMID: 20176612
anaemia; chronic kidney failure; creatinine; cystatin C; glomerular filtration rate
22.  Chronic kidney disease and venous thromboembolism: a prospective study 
Nephrology Dialysis Transplantation  2010;25(10):3296-3301.
Background. The incidence of venous thromboembolism (VTE) is increased with severe kidney disease, but whether less-severe chronic kidney disease (CKD) increases the risk of VTE is less certain.
Methods. We studied this in a prospective cohort of 10 700 whites and African Americans, aged 53–75 years, attending Visit 4 (1996–98) of the Atherosclerosis Risk in Communities Study. Estimated glomerular filtration rate (eGFR) values were estimated from prediction equations based on serum creatinine (eGFRcreat) or cystatin C (eGFRcys). Normal kidney function was defined as eGFR ≥90 ml/min/1.73 m2, mildly decreased kidney function as eGFR between 60 and 89 ml/min/1.73 m2 and Stage 3 to 4 CKD as eGFR between 15 and 59 ml/min/1.73 m2. VTE occurrence (n = 228) was ascertained over a median of 8.3 years.
Results. For eGFRcys, the age-, race- and sex-adjusted hazard ratios of total VTE were 1.0, 1.40 and 1.94 (P trend = 0.003) for normal kidney function, mildly impaired kidney function and Stage 3 to 4 CKD, respectively. These respective hazard ratios were moderately attenuated to 1.0, 1.26 and 1.60 (P trend = 0.04) with adjustment for hormone replacement therapy, diabetes and body mass index. Associations between CKD based on eGFRcys and VTE were slightly stronger for idiopathic VTE than for secondary VTE. In contrast, CKD based on eGFRcreat was not associated with total VTE occurrence.
Conclusions. Stage 3 to 4 CKD, based on eGFRcys but not eGFRcreat, was associated with an approximately 1.6-fold increased risk of VTE.
doi:10.1093/ndt/gfq179
PMCID: PMC2948836  PMID: 20353958
chronic kidney disease; prospective study; pulmonary embolism; venous thromboembolism
23.  Electronically-measured adherence to immunosuppressive medications and kidney function after deceased donor kidney transplantation* 
Clinical transplantation  2010;25(2):E124-E131.
Background
Non-adherence with immunosuppressive medications can result in allograft rejection and eventually allograft loss.
Methods
In a racially diverse population, we utilized microelectronic cap monitors to determine the association of adherence with a single immunosuppressive medication and kidney allograft outcomes post-transplantation. This prospective cohort study enrolled 243 patients from eight transplant centers to provide adherence and kidney allograft outcomes data. To determine the association of adherence with change in estimated glomerular filtration rate (eGFR), we fit mixed effects models with the outcome being change in eGFR over time. We also fit Cox proportional hazards models to determine the association of adherence with time to persistent 25% and 50% decline in eGFR.
Results
The distribution of adherence post-transplant was as follows: 164 (68%), 49 (20%) and 30 (12%) had >85–100%, 50–85% and <50% adherence, respectively. 79 (33%) and 36 (15%) of the subjects experienced a persistent 25% decline in eGFR or allograft loss and 50% decline in eGFR or allograft loss during follow-up. Adherence was not associated with acute rejection or 25% decline or 50% decline in eGFR. In the adjusted and unadjusted model, adherence and black race were not associated with change in eGFR over time.
Conclusions
Non-adherence with a single immunosuppressive medication, was not associated with kidney allograft outcomes.
doi:10.1111/j.1399-0012.2010.01340.x
PMCID: PMC3566245  PMID: 20977496
kidney transplant; adherence; renal function
24.  Influence of albuminuria and glomerular filtration rate on blood pressure response to antihypertensive drug therapy 
Vascular Health and Risk Management  2007;3(6):1029-1037.
Background
Albuminuria and glomerular filtration rate (GFR), two factors linked to kidney and vascular function, may influence longitudinal blood pressure (BP) responses to complex antihypertensive drug regimens.
Methods
We reviewed the clinic records of 459 patients with hypertension in an urban, academic practice.
Results
Mean patient age was 57-years, 89% of patients were African American, and 69% were women. Mean patient systolic/diastolic BP (SBP/DBP) at baseline was 171/98 mmHg while taking an average of 3.3 antihypertensive medications. At baseline, 27% of patients had estimated (e)GFR <60 ml/min/1.732, 28% had micro-albuminuria (30–300 mg/g) and 16% had macro-albuminuria (>300 mg/g). The average longitudinal BP decline over the observation period (mean 7.2 visits) was 25/12 mmHg. In adjusted regression models, macro-albuminuria predicted a 10.3 mmHg lesser longitudinal SBP reduction (p < 0.001) and a 7.9 mmHg lesser longitudinal DBP reduction (p < 0.001); similarly eGFR <60 ml/min/1.732 predicted an 8.4 mmHg lesser longitudinal SBP reduction (p < 0.001) and a 4.5 lesser longitudinal DBP reduction (p < 0.001). Presence of either micro- or macro-albuminuria, or lower eGFR, also significantly delayed the time to attainment of goal BP.
Conclusions
These data suggest that an attenuated decline in BP in drug-treated hypertensives, resulting in higher average BP levels over the long-term, may mediate a portion of the increased risk of cardiovascular-renal disease linked to elevated urinary albumin excretion and reduced eGFR.
PMCID: PMC2350134  PMID: 18200821
albuminuria; glomerular filtration rate; blood pressure; antihypertensive drug therapy
25.  Kidney Function Decline in the Elderly: Impact of Lipoprotein-Associated Phospholipase A2 
American Journal of Nephrology  2011;34(6):512-518.
Background: Whether lipoprotein-associated phospholipase A2 (Lp-PLA2) levels are associated with kidney function decline has not been well studied. Methods: We investigated associations of Lp-PLA2 antigen and activity with kidney function decline and rapid decline over 5.7 years in the Cardiovascular Health Study (n = 4,359). We estimated kidney function by cystatin C (eGFRcys) in repeated measures, and defined rapid decline as ≥3 ml/min/1.73 m2 per year. We stratified by baseline preserved GFR (≥60 ml/min/1.73 m2). Results: Mean age was 72 ± 5 years. Average eGFRcys decline was −1.79 ml/min/1.73 m2 (SD = 2.60) per year. Among persons with preserved GFR, compared to the lowest quartile of Lp-PLA2 antigen, eGFRcys decline was faster among persons in the second, β −0.31 (95% CI −0.52, −0.10), third −0.19 (–0.41, 0.02) and fourth quartiles −0.26 (–0.48, −0.04) after full adjustment. Persons in the highest quartile of Lp-PLA2 antigen had increased odds of rapid decline 1.34 (1.03, 1.75), compared to the lowest. There was no significant association between levels of Lp-PLA2 activity and eGFRcys decline or rapid decline. Associations were not statistically significant among persons with low eGFR (<60 ml/min/1.73 m2) at baseline. Conclusion: Higher levels of Lp-PLA2 antigen but not activity were significantly associated with faster rates of kidney function decline. These findings may suggest a novel vascular pathway for kidney disease progression.
doi:10.1159/000333045
PMCID: PMC3225232  PMID: 22056971
Chronic kidney disease; Elderly; Estimated GFR; Kidney decline; Lipoprotein-associated phospholipase A2

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