Association of kidney disease index with all-cause and cardiovascular mortality among individuals with hypertension

BACKGROUND

This study aimed to investigate the association between a novel kidney disease index (KDI), which combines information from both estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (uACR), and all-cause and cardiovascular disease (CVD) mortality among individuals with hypertension.

METHODS

We analyzed data from 19 988 adults with hypertension who participated in the National Health and Nutrition Examination Survey from 1999 to 2018. Mortality outcomes were determined by linking to National Death Index records through December 31, 2019. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for all-cause and CVD mortality.

RESULTS

Baseline KDI levels were positively associated with glucose, insulin resistance, hemoglobin A1c, triglycerides, and C-reactive protein (p value for trend <.05). During a follow-up period of 179 859 person-years, a total of 5069 deaths were documented, including 1741 from cardiovascular causes. After multivariable adjustment, each standard deviation increment in KDI level was associated with a 27% increased risk of all-cause mortality and a 31% increased risk of cardiovascular deaths (both p < .05). Further analysis showed a J-shaped association between KDI and mortality, with the risk increasing dramatically when KDI exceeded 0.27.

CONCLUSION

Elevated KDI levels were significantly associated with increased mortality from all causes and CVD among individuals with hypertension. We recommend routine testing of eGFR and uACR in hypertensive patients, and using KDI as a tool to identify individuals who are most likely to benefit from preventive therapies.

Podocyte-Related Mechanisms Underlying Survival Benefit of Long-Term Angiotensin Receptor Blocker

We previously found that short-term treatment (week 8 to 12 after injury) with high-dose angiotensin receptor blocker (ARB) induced the regression of existing glomerulosclerosis in 5/6 nephrectomy rats. We therefore assessed the effects of long-term intervention with ARB vs. nonspecific antihypertensives in this study. Adult rats underwent 5/6 nephrectomy and renal biopsy 8 weeks later. The rats were then divided into three groups with equivalent renal function and glomerular sclerosis and treated with high-dose losartan (ARB), nonspecific antihypertensive triple-therapy (TRX), or left untreated (Control) until week 30. We found that blood pressure, serum creatinine levels, and glomerulosclerosis were lower at sacrifice in ARB and TRX vs. Control. Only ARB reduced proteinuria and maintained the density of WT-1-positive podocytes. Glomerular tufts showed more double-positive cells for CD44, a marker of activated parietal epithelial cells, and synaptopodin after ARB vs. TRX or Control. ARB treatment reduced aldosterone levels. ARB-treated rats had significantly improved survival when compared with TRX or Control. We conclude that both long-term ARB and triple-therapy ameliorate progression, but do not sustain the regression of glomerulosclerosis. ARB resulted in the superior preservation of podocyte integrity and decreased proteinuria and aldosterone, linked to increased survival in the uremic environment.

Kidney disease parameters, metabolic goal achievement, and arterial stiffness risk in Chinese adult people with type 2 diabetes

BACKGROUND

To investigate the arterial stiffness (AS) risk within urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) categories and the joint effect between kidney disease parameters and metabolic goal achievement on AS risk in adult people with type 2 diabetes (T2D).

METHODS

A total of 27 439 Chinese participants with T2D from 10 National Metabolic Management Centers (MMC) were categorized into four albuminuria/decreased eGFR groups. The criteria for decreased eGFR and AS were eGFR <90 ml/min/1.73 m² and brachial-ankle pulse wave velocity value >the 75th percentile (1770.0 cm/s). Three metabolic goals were defined as glycated hemoglobin <7%, BP <130/80 mmHg, andlow-density lipoprotein cholesterol <2.6 mmol/L.

RESULTS

After full adjustment, odds ratios (ORs) for AS were highest for albuminuria and decreased eGFR (2.23 [1.98-2.52]) and were higher for albuminuria and normal eGFR (1.52 [1.39-1.67]) than for those with nonalbuminuria and decreased eGFR (1.17 [1.04-1.32]). Both UACR and eGFR in the subgroup or overall population independently correlated with AS risk. The achievement of ≥2 metabolic goals counteracted the association between albuminuria and AS risk (OR: 0.93; 95% CI: 0.80-1.07; p = .311). When the metabolic goals added up to ≥2 for patients with decreased eGFR, they showed significantly lower AS risk (OR: 0.65; 95% CI: 0.56-0.74; p < .001).

CONCLUSIONS

Both higher UACR and lower eGFR are determinants of AS risk, with UACR more strongly related to AS than eGFR in adults with T2D. The correlation between albuminuria/decreased eGFR and AS was modified by the achievement of multiple metabolic elements.

Albuminuria predicts worsening renal function after transcatheter aortic valve replacement

BACKGROUND

The impact of albuminuria on worsening renal function (WRF) and clinical outcomes after transcatheter aortic valve replacement (TAVR) is unknown.

METHODS

Overall, 142 patients who underwent TAVR for severe aortic stenosis were divided into two groups based on the preoperative urinary albumin-to-creatinine ratio (ACR): high (ACR ≥30 mg/g) and low (ACR <30 mg/g). The incidence of WRF (an absolute increase in serum creatinine level of ≥0.3 mg/dL or ≥1.5-fold from baseline or dialysis initiation) at 6 months after TAVR and the incidence of all-cause death and heart failure readmission during follow-up were investigated.

RESULTS

Half of the examined patients [n=71/142 (50.0%)] had a high ACR. Patients with a high ACR more frequently had WRF at 6 months than those with a low ACR (17.6% vs. 2.9%, p=0.004). Multivariate analysis showed a high ACR was independently associated with WRF (odds ratio, 7.76; 95% confidence interval, 1.62-37.30; p=0.01), whereas baseline estimated glomerular filtration rate <60 mL/min/1.73m² was not (odds ratio, 0.34; 95% confidence interval, 0.08-1.50; p=0.15). Patients with a high ACR had a higher risk of composite outcomes of all-cause death and heart failure readmission (p=0.002).

CONCLUSIONS

Preoperative albuminuria (ACR ≥30 mg/g) was independently associated with WRF at 6 months after TAVR. Furthermore, patients with an ACR ≥30 mg/g had higher risks of all-cause death and heart failure readmission than those with an ACR <30 mg/g.

Smoking tobacco is associated with renal hyperfiltration

Tobacco consumption is a renal risk factor, but the effects on the estimated glomerular filtration rate (eGFR) remain unclear. We aimed to evaluate the possible impact of using tobacco products (smoking and snus) on eGFR based on creatinine or cystatin C. We used a first cohort with 949 participants and a second cohort with 995 participants; none had pre-existing renal disease. All subjects donated a blood sample and completed a questionnaire, including questions about tobacco use. To assess the effect on eGFR, hierarchical multiple linear regression models were used. Active smoking associated independently with a higher eGFRcreatinine in all subjects (p < 0.001; β = 0.11). Further analyses stratified for sex, showed similar findings for men (p < 0.001; β = 0.14) and for women (p = 0.026; β = 0.10). eGFRcystatin C was significantly associated with active smoking in all subjects (p = 0.040; β = -0.05), but no association was seen after stratification for sex. Snus did not associate with eGFR. In conclusion, smoking associated significantly with a higher eGFRcreatinine. The mechanism may be renal hyperfiltration of smaller molecules such as creatinine. This is probably caused by substances from smoked tobacco other than nicotine, as no effect was seen for snus.

Association between renal function and cardiovascular mortality: a retrospective cohort study of elderly from health check-up

OBJECTIVES

This study aimed to investigate the relationship between cardiovascular mortality in elderly Asians and decline in renal function.

DESIGN

A retrospective cohort study.

SETTING

Community-based health examination database from Taipei city.

PARTICIPANTS

At the beginning, the database included 315 045 health check-up visits of 97 803 elderly persons aged ≥65 years old from 2005 to 2012. After excluding missing values and outliers, there were 64 732 elderly persons with at least two visits retained for further analyses.

PRIMARY OUTCOME MEASURES

Kidney function indicators include estimated glomerular filtration rate (eGFR) and urine protein, and rapid decline in eGFR was defined as slope ≤ -5 mL/min/1.73 m² per year. The endpoint outcome was defined as the cardiovascular deaths registered in the death registry encoded by the International Classification of Diseases. We applied a Cox proportional hazards model to analyse the association between renal function and cardiovascular mortality.

RESULTS

In this study, we found 1264 elderly persons died from cardiovascular diseases, for whom the data included 4055 previous health check-up visits. We observed significant and independent associations of eGFR <60 mL/min/1.73 m² (HR (95% CI) of 60>eGFR≥45 and eGFR<45 in males: 2.85 (1.33 to 6.09) and 3.98 (1.84 to 8.61); in females: 3.66 (1.32 to 10.15) and 6.77 (2.41 to 18.99)), positive proteinuria (HR (95% CI) of +/-, +,++ and +++, ++++ in males: 1.51 (1.29 to 1.78) and 2.31 (1.51 to 3.53); in females: 1.93 (1.54 to 2.42) and 4.23 (2.34 to 7.65)) and rapid decline in eGFR (HR (95% CI) in males: 3.24 (2.73 to 3.85); in females: 2.83 (2.20 to 3.64) with higher risk of cardiovascular mortality. The joint effect of increased concentration of urine protein and reduced eGFR was associated with a higher risk of cardiovascular mortality.

CONCLUSIONS

Renal function and rapid decline in renal function are independent risk factors for cardiovascular mortality in the elderly.

Mild impairment of renal function (shrunken pore syndrome) is associated with increased risk of a future first-ever myocardial infarction in women

Impaired renal function is associated both with the development of cardiovascular disease and its prognosis. A new syndrome called 'Shrunken Pore Syndrome' has been suggested, as the estimated glomerular filtration rate for cystatin C (eGFR_{cystatin C}) is affected earlier due to differences in molecular size compared to eGFR_creatinine. The aim was to investigate if a lower eGFR_{cystatin C}/eGFR_creatinine ratio in a prospective setting increases the risk of later developing a first-ever myocardial infarction (MI) independently of other cardiovascular risk factors. We used a nested case-referent study design within the Northern Sweden Health and Disease Study, and 545 subjects (29.0% women) were identified who prospectively developed a first-ever MI, and their 1054 matched referents. For women, but not for men, one standard deviation (SD) increase of ln z-scores of eGFR_{cystatin C}/eGFR_creatinine ratio was associated with a lower risk of a future MI: odds ratio [95% confidence interval] 0.58 [0.34-0.99], adjusted for apolipoprotein B/A1 ratio, CRP, homocysteine, systolic blood pressure, body mass index, and diabetes. Furthermore, a high eGFR_creatinine associated independently with an increased risk of future MI in men only: OR 1.25 [1.05-1.48]. Thus, for women, a lower eGFR_{cystatin C}/eGFR_creatinine ratio is associated with a higher risk of having a future first-ever MI, and it may be a valuable, easily implemented biomarker for risk of cardiovascular disease.

Costs and Healthcare Resource Use Associated with Risk of Cardiovascular Morbidity in Patients with Chronic Kidney Disease: Evidence from a Systematic Literature Review

Introduction

The management of chronic kidney disease (CKD) costs in excess of $114 billion in the USA and £1.45 billion in the UK annually and is projected to increase alongside the increasing disease prevalence. The aim of this review was to evaluate the risks of cardiovascular (CV) morbidity, CV mortality or all-cause mortality based on KDIGO (Kidney Disease: Improving Global Outcomes) 2012 categorisations and estimate the additional costs and healthcare resource utilisation associated with CV morbidity linked to CKD severity in US and UK settings.

Methods

A systematic literature review was conducted of studies reporting on the risk of CV morbidity, CV mortality or all-cause mortality characterised by CKD severity (published between January 2000 and September 2018). Additional costs and bed days associated with CKD severity in the USA and UK were estimated on the basis of median hazard ratios for CV morbidity risk at each CKD and albuminuria stage.

Results

Twenty-nine studies reported risk of adverse clinical outcomes based on KDIGO categorisations. Compared to stage 1 (or without) CKD, patients with stage 5 CKD and macroalbuminuria experienced a relative risk increase of 11.77–12.46 across all outcomes. Additional costs and bed days associated with stage 5 CKD and macroalbuminuria (versus stage 1 (or without) CKD) per 1000 patient years were US$3.93 million and 803 bed days and £435,000 and 1017 bed days, in the USA and UK, respectively.

Conclusion

Risks of adverse clinical outcomes increase with CKD and albuminuria severity and are associated with substantial additional costs and resource utilisation. Thus, early diagnosis and proactive management of CKD and its complications should be a priority for healthcare providers to alleviate the burden of CV morbidity and its management on healthcare resources.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-020-01607-4.

Kidney Function as Risk Factor and Predictor of Cardiovascular Outcomes and Mortality Among Older Adults

RATIONALE & OBJECTIVE

Estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) are associated with cardiovascular events in the general population but their utility among older adults is unclear. We investigated the associations of eGFR and UACR with stroke, myocardial infarction (MI), and death among older adults.

STUDY DESIGN

Population-based cohort study.

SETTING & PARTICIPANTS

1,581 participants (aged≥70 years) in the Berlin Initiative Study (BIS) without prior stroke or MI.

EXPOSURES & PREDICTORS

Serum creatinine- and cystatin C-based eGFR, UACR categories, and measured GFR (n=436).

OUTCOMES

Stroke, MI, and all-cause mortality.

ANALYTICAL APPROACH

HRs and 95% CIs derived from multivariable-adjusted Cox proportional hazards models for association analyses. Net reclassification improvement (NRI) and C statistic differences comparing the predictive benefit of kidney measures with a traditional cardiovascular risk model.

RESULTS

During a median follow-up of 8.2 years, 193 strokes, 125 MIs, and 531 deaths occurred. Independent of UACR, when GFR was estimated using the creatinine- and cystatin C-based BIS equation, eGFR of 45 to 59mL/min/1.73m² (vs eGFR>60mL/min/1.73m²) was associated with stroke (HR, 2.23; 95% CI, 1.55-3.21) but not MI or all-cause mortality. For those with eGFR<45mL/min/1.73m², the HRs were 1.99 (95% CI, 1.23-3.20) for stroke, 1.38 (95% CI, 0.81-2.36) for MI, and 1.57 (95% CI, 1.20-2.06) for mortality. Compared with UACR<30mg/g, UACR of 30 to 300mg/g was not associated with stroke (HR, 0.91; 95% CI, 0.63-1.33) but was associated with MI (HR, 1.65; 95% CI, 1.09-2.51) and all-cause mortality (HR, 1.63; 95% CI, 1.34-1.98). Prediction analysis for stroke showed significant positive NRI for eGFR calculated using the cystatin C-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and the creatinine- and cystatin C-based BIS and Full Age Spectrum equations. UACR demonstrated significant positive NRIs for MI and mortality.

LIMITATIONS

eGFR and UACR categorization based on single assessments; lack of cause-specific death data.

CONCLUSIONS

eGFR of 45 to 59mL/min/1.73m² without albuminuria was associated with stroke but not MI or all-cause mortality in older adults. In contrast, UACR of 30 to 300mg/g was associated with MI and all-cause mortality but not with stroke. Furthermore, cystatin C-based eGFR improved risk prediction for stroke in this cohort of older adults.

Associations Between Kidney Disease Measures and Regional Pulse Wave Velocity in a Large Community-Based Cohort: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Arterial stiffness is suggested as a mediator of cardiorenal interaction. However, previous studies reported inconsistent associations between chronic kidney disease (CKD) and arterial stiffness and were limited by using either estimated glomerular filtration rate (eGFR) or albumin-creatinine ratio (ACR) and examining arterial stiffness at limited segments.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

3,424 Atherosclerosis in Communities (ARIC) Study participants aged 66 to 90 years during 2011 to 2013.

PREDICTORS

eGFR and ACR.

OUTCOME

Pulse wave velocity (PWV) at 6 segments: carotid-femoral (cfPWV), heart-carotid (hcPWV), and heart-femoral (hfPWV), reflecting central stiffness; heart-ankle (haPWV) and brachial-ankle (baPWV), representing both central and peripheral stiffness; and femoral-ankle (faPWV), indicating peripheral stiffness.

ANALYTICAL APPROACH

Multiple linear and logistic regression models to quantify the associations of eGFR and ACR with continuous PWV and elevated PWV (in the highest quartile), respectively.

RESULTS

After adjusting for age, sex, and race, higher cfPWV and hfPWV were consistently associated with lower eGFR and higher ACR. Higher haPWV and baPWV were also observed with higher ACR. The independent association of both CKD measures with elevated cfPWV remained consistent after adjusting for additional confounders (ORs of elevated cfPWV were 1.09 [95% CI, 1.01-1.18] per 15-mL/min/1.73m² lower eGFR and 1.20 [95% CI, 1.07-1.33] per 4-fold higher ACR). Higher ACR was also associated with elevated hfPWV and haPWV (ORs per 4-fold higher ACR were 1.25 [95% CI, 1.12-1.39] for elevated hfPWV and 1.19 [95% CI, 1.06-1.33] for elevated haPWV). Lower eGFR was associated with lower odds of elevated baPWV and faPWV (ORs per 15-mL/min/1.73m² lower eGFR were 0.92 [95% CI, 0.84-0.99] and 0.91 [95% CI, 0.85-0.99], respectively).

LIMITATION

Unable to address temporality between CKD measures and arterial stiffness.

CONCLUSIONS

Both lower eGFR and higher ACR are independently associated with measures of central arterial stiffness, with stronger associations for ACR over eGFR. Our findings suggest that central arterial stiffness may be an important pathophysiologic phenotype of vascular disease in CKD.

Post-Discharge Worsening Renal Function in Patients with Type 2 Diabetes and Recent Acute Coronary Syndrome

BACKGROUND

Worsening renal function during hospitalization for an acute coronary syndrome is strongly predictive of in-hospital and long-term outcome. However, the role of post-discharge worsening renal function has never been investigated in this setting.

METHODS

We considered the placebo cohort of the AleCardio trial comparing aleglitazar with standard medical therapy among patients with type 2 diabetes mellitus and a recent acute coronary syndrome. Patients who had died or had been admitted to hospital for heart failure before the 6-month follow-up, as well as patients without complete renal function data, were excluded, leaving 2776 patients for the analysis. Worsening renal function was defined as a >20% reduction in estimated glomerular filtration rate from discharge to 6 months, or progression to macroalbuminuria. The Cox regression analysis was used to determine the prognostic impact of 6-month renal deterioration on the composite of all-cause death and hospitalization for heart failure.

RESULTS

Worsening renal function occurred in 204 patients (7.34%). At a median follow-up of 2 years the estimated rates of death and hospitalization for heart failure per 100 person-years were 3.45 (95% confidence interval [CI], 2.46-6.36) for those with worsening renal function, versus 1.43 (95% CI, 1.14-1.79) for patients with stable renal function. At the adjusted analysis worsening renal function was associated with the composite endpoint (hazard ratio 2.65; 95% CI, 1.57-4.49; P <.001).

CONCLUSIONS

Post-discharge worsening renal function is not infrequent among patients with type 2 diabetes and acute coronary syndromes with normal or mildly depressed renal function, and is a strong predictor of adverse cardiovascular events.

Serum uromodulin predicts graft failure in renal transplant recipients

OBJECTIVE AND METHODS

Test the ability of serum uromodulin concentrations 1-3 months after renal transplantation to predict all-cause mortality (ACM) and graft loss (GL) in 91 patients.

RESULTS

uromodulin predicted GL equivalently to the other markers studied: the risk for GL was reduced by 0.21 per one standard deviation (SD) increase (cystatin C: hazard ratio [HR] 4.57, creatinine: HR 4.53, blood-urea-nitrogen [BUN]: HR 2.50, estimated glomerular filtration rate [eGFR]: HR 0.10). In receiver-operating-characteristic (ROC) analysis, uromodulin predicted GL with an area-under-the curve of 0.782 at an optimal cut-off (OCO) of 24.0 ng/ml with a sensitivity of 90.0% and a specificity of 70.2%.

CONCLUSION

Serum uromodulin predicted GL equivalently compared to conventional biomarkers of glomerular filtration.

Cardiovascular risk prediction in people with chronic kidney disease

PURPOSE OF REVIEW

Clinical guidelines are not consistent regarding whether or how to utilize information on measures of chronic kidney disease (CKD) for predicting the risk of cardiovascular disease (CVD). This review summarizes recent literature regarding CVD prediction in the context of CKD.

RECENT FINDINGS

Previous studies used different definitions of CKD measures and CVD outcomes, and applied distinct statistical approaches. A recent individual-level meta-analysis from the CKD Prognosis Consortium is of value as it has uniformly investigated creatinine-based estimated glomerular filtration rate (eGFR) and albuminuria as CKD measures and applied the same statistical approach across 24 cohorts with more than 630 000 participants. In this meta-analysis, eGFR and albuminuria improve CVD risk prediction beyond traditional CVD risk factors, particularly for CVD mortality and heart failure. Albuminuria demonstrates more evident improvement than eGFR. Moreover, several recent studies have shown that other filtration markers, for example, cystatin C and β2-microglobulin, and measures of atherosclerosis or cardiac damage (e.g., coronary artery calcium and cardiac troponins) can further improve CVD prediction in the CKD population.

SUMMARY

Future clinical guidelines may require updates regarding whether/how to incorporate CKD measures and other biomarkers in CVD prediction, depending on the CVD outcomes of interest, target population, and availability of those measures/biomarkers in that population.

Associations between urinary kidney injury biomarkers and cardiovascular mortality risk in elderly men with diabetes

AIM

Three urinary biomarkers, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and cystatin C, have been suggested as clinically relevant highly specific biomarkers of acute kidney tubular damage. Yet, the utility of these biomarkers in the prognostication of diabetic nephropathy has been less studied. Therefore, we aimed to investigate the longitudinal association between these urinary biomarkers and cardiovascular mortality in patients with diabetes.

METHODS

The study sample consisted of participants with diabetes in the community-based Uppsala Longitudinal Study of Adult Men (n = 91; mean age 77.8 years). During follow-up (median 8.3 years, interval 0.7-13.4 years), 33 participants died of cardiovascular causes.

RESULTS

In a multivariable Cox regression model adjusting for age, glomerular filtration rate, and urinary albumin/creatinine ratio, higher urinary KIM-1/creatinine was associated with an increased risk for cardiovascular mortality (HR per SD increase 1.51, 95% confidence intervals 1.03-2.24, P = 0.03). Neither urinary NGAL/creatinine nor urinary cystatin C/creatinine were independently associated with an increased cardiovascular mortality risk.

CONCLUSION

In elderly men with diabetes, higher urinary KIM-1/creatinine was associated with an increased long-term risk of cardiovascular mortality independently of established markers of diabetic nephropathy. Our data provide support for kidney tubular damage as an important aspect of diabetic nephropathy that merits further investigation.

Cystatin C estimated glomerular filtration rate and all-cause and cardiovascular disease mortality risk in the general population: AusDiab study

AIMS

Uncertainties about the role of cystatin C-based estimated glomerular filtration rate (eGFR) in the prediction of cardiovascular disease (CVD) beyond traditional CVD risk factors remain. We assessed contributions of eGFR to CVD and mortality in the general population.

METHODS

Using 14 year follow-up data on 9353 adults without a reported history of CVD from the Australian Diabetes, Obesity and Lifestyle study, we assessed the contributions of eGFR (assessed by cystatin C (eGFR_cysC ) and serum creatinine (eGFR_cr ) and albuminuria (uACR) to total and CVD mortality.

RESULTS

After adjusting for age, sex, CVD risk factors and uACR, compared with an eGFR_cysC >90 mL/min per 1.73 m² , eGFR_cysC <60 mL/min per 1.73 m² was associated with 56% and 73% increases in the risks for all-cause and CVD mortality, respectively. The respective changes for the c-statistic when eGFR_cysC was added to a risk prediction model were 0.003 (95% confidence interval: 0.001 to 0.005) and 0.002 (95% confidence interval: -0.001 to 0.006). The net proportion of non-events assigned a lower-risk category significantly improved with the addition of eGFR (non-event net reclassification index eGFR_cr : 1.0% and eGFR_cysC : 1.5%) for all-cause mortality, but for CVD mortality, improvements were only significant when eGFR was combined with uACR. The net proportion of events assigned a higher-risk category was not significantly improved.

CONCLUSION

In our community-based cohort, reduced eGFR_cysC was associated with all-cause and CVD mortality. The addition of chronic kidney disease measures to risk prediction models improved overall risk stratification among those at low risk as opposed to those at high baseline risk of mortality.

Comparison between Cystatin C- and Creatinine-Estimated Glomerular Filtration Rate in Cardiology Patients

OBJECTIVE

Estimation of the glomerular filtration rate (GFR) is essential for identification, evaluation and risk prediction in patients with kidney disease. Estimated GFR (eGFR) is also needed for the correct dosing of drugs eliminated by the kidneys and to identify high-risk individuals in whom coronary angiography or other procedures may lead to kidney failure. Both cystatin C and creatinine are used for the determination of GFR, and we aimed to investigate if eGFR by the two methods differ in cardiology patients.

METHODS

We compared cystatin C and creatinine (CKD-EPI) eGFR calculated from the same request from a cardiology outpatient unit (n = 2,716), a cardiology ward (n = 980), a coronary care unit (n = 1,464), and an advanced coronary care unit (n = 518) in an observational, cross-sectional study.

RESULTS

The median creatinine eGFR results are approximately 10 ml/min/1.73 m(2) higher than the median cystatin C eGFR that is up to 90 ml/min/1.73 m(2), irrespective of the level of care. Creatinine eGFR resulted in a less advanced eGFR category in the majority of patients with a cystatin C eGFR <60 ml/min/1.73 m(2).

CONCLUSIONS

Our study demonstrates a difference between creatinine and cystatin C eGFR in cardiology patients. It is important to be aware of which marker is used for the reported eGFR to minimize erroneous interpretations of the test results, as this could lead to under- or overmedication. Further studies are needed to determine the best method of estimating the GFR in cardiology units.

Estimated glomerular filtration rate and albuminuria for prediction of cardiovascular outcomes: a collaborative meta-analysis of individual participant data

BACKGROUND

The usefulness of estimated glomerular filtration rate (eGFR) and albuminuria for prediction of cardiovascular outcomes is controversial. We aimed to assess the addition of creatinine-based eGFR and albuminuria to traditional risk factors for prediction of cardiovascular risk with a meta-analytic approach.

METHODS

We meta-analysed individual-level data for 637 315 individuals without a history of cardiovascular disease from 24 cohorts (median follow-up 4·2-19·0 years) included in the Chronic Kidney Disease Prognosis Consortium. We assessed C statistic difference and reclassification improvement for cardiovascular mortality and fatal and non-fatal cases of coronary heart disease, stroke, and heart failure in a 5 year timeframe, contrasting prediction models for traditional risk factors with and without creatinine-based eGFR, albuminuria (either albumin-to-creatinine ratio [ACR] or semi-quantitative dipstick proteinuria), or both.

FINDINGS

The addition of eGFR and ACR significantly improved the discrimination of cardiovascular outcomes beyond traditional risk factors in general populations, but the improvement was greater with ACR than with eGFR, and more evident for cardiovascular mortality (C statistic difference 0·0139 [95% CI 0·0105-0·0174] for ACR and 0·0065 [0·0042-0·0088] for eGFR) and heart failure (0·0196 [0·0108-0·0284] and 0·0109 [0·0059-0·0159]) than for coronary disease (0·0048 [0·0029-0·0067] and 0·0036 [0·0019-0·0054]) and stroke (0·0105 [0·0058-0·0151] and 0·0036 [0·0004-0·0069]). Dipstick proteinuria showed smaller improvement than ACR. The discrimination improvement with eGFR or ACR was especially evident in individuals with diabetes or hypertension, but remained significant with ACR for cardiovascular mortality and heart failure in those without either of these disorders. In individuals with chronic kidney disease, the combination of eGFR and ACR for risk discrimination outperformed most single traditional predictors; the C statistic for cardiovascular mortality fell by 0·0227 (0·0158-0·0296) after omission of eGFR and ACR compared with less than 0·007 for any single modifiable traditional predictor.

INTERPRETATION

Creatinine-based eGFR and albuminuria should be taken into account for cardiovascular prediction, especially when these measures are already assessed for clinical purpose or if cardiovascular mortality and heart failure are outcomes of interest. ACR could have particularly broad implications for cardiovascular prediction. In populations with chronic kidney disease, the simultaneous assessment of eGFR and ACR could facilitate improved classification of cardiovascular risk, supporting current guidelines for chronic kidney disease. Our results lend some support to also incorporating eGFR and ACR into assessments of cardiovascular risk in the general population.

FUNDING

US National Kidney Foundation, National Institute of Diabetes and Digestive and Kidney Diseases.

Nonesterified fatty acids and cardiovascular mortality in elderly men with CKD

BACKGROUND AND OBJECTIVES

Although nonesterified fatty acids (NEFAs) are essential as energy substrate for the myocardium, an excess of circulating NEFAs can be harmful. This study aimed to assess plausible relationships between serum NEFA and mortality due to cardiovascular disease (CVD) in individuals with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective cohort study from the third examination cycle of the Uppsala Longitudinal Study of Adult Men, a population-based survey of 1221 elderly men aged 70-71 years residing in Uppsala, Sweden. Data collection took place during 1991-1995. All participants had measures of kidney function; this study investigated 623 (51.7%) of these patients with manifest CKD (defined as either eGFR<60 ml/min per 1.73 m(2) or urine albumin excretion rate ≥20 µg/min). Follow-up for mortality was done from examination date until death or December 31, 2007. After a median follow-up of 14 years (interquartile range, 8-16.8), associations of NEFAs with mortality (related to all causes, CVD, ischemic heart disease [IHD], or acute myocardial infarction) were ascertained.

RESULTS

The median serum NEFA was 14.1 mg/dl (interquartile range, 11.3-17.8). No association was found with measures of kidney function. Diabetes and serum triglycerides were the only multivariate correlates of NEFA. During follow-up, 453 participants died, of which 209 deaths were due to CVD, including 88 IHD deaths, with 41 attributed to acute myocardial infarction (AMI). In fully adjusted covariates, serum NEFA was an independent risk factor for all-cause mortality (hazard ratio [HR] per log2 increase, 1.22; 95% confidence interval [95% CI], 1.00 to 1.48) and CVD-related death (HR, 1.51; 95% CI, 1.15 to 1.99), including both IHD (HR, 1.51; 95% CI, 1.00 to 2.32) and AMI mortality (HR, 2.08; 95% CI, 1.09 to 3.98).

CONCLUSIONS

Elevated serum NEFA associated with CVD mortality, and particularly with mortality due to AMI, in a homogeneous population of older men with moderate CKD.

Urinary kidney injury molecule-1 and the risk of cardiovascular mortality in elderly men

BACKGROUND AND OBJECTIVES

Kidney injury molecule-1 (KIM-1) has been suggested as a clinically relevant highly specific biomarker of acute kidney tubular damage. However, community-based data on the association between urinary levels of KIM-1 and the risk for cardiovascular mortality are lacking. This study aimed to investigate the association between urinary KIM-1 and cardiovascular mortality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective study, using the community-based Uppsala Longitudinal Study of Adult Men (N=590; mean age 77 years; baseline period, 1997-2001; median follow-up 8.1 years; end of follow-up, 2008).

RESULTS

During follow-up, 89 participants died of cardiovascular causes (incidence rate, 2.07 per 100 person-years at risk). Models were adjusted for cardiovascular risk factors (age, systolic BP, diabetes, smoking, body mass index, total cholesterol, HDL cholesterol, antihypertensive treatment, lipid-lowering treatment, aspirin treatment, and history of cardiovascular disease) and for markers of kidney dysfunction and damage (cystatin C-based eGFR and urinary albumin/creatinine ratio). Higher urinary KIM-1/creatinine (from 24-hour urine collections) was associated with a higher risk for cardiovascular mortality (hazard ratio per SD increase, 1.27; 95% confidence interval [95% CI], 1.05 to 1.54; P=0.01). Participants with a combination of high KIM-1/creatinine (upper quintile, ≥175 ng/mmol), low eGFR (≤60 ml/min per 1.73 m(2)), and microalbuminuria/macroalbuminuria (albumin/creatinine ratio≥3 g/mol) had a >8-fold increased risk compared with participants with low KIM-1/creatinine (<175 ng/mmol), normal eGFR (>60 ml/min per 1.73 m(2)), and normoalbuminuria (albumin/creatinine ratio<3 g/mol) (hazard ratio, 8.56; 95% CI, 4.17 to 17.56; P<0.001).

CONCLUSIONS

These findings suggest that higher urinary KIM-1 may predispose to a higher risk of cardiovascular mortality independently of established cardiovascular risk factors, eGFR, and albuminuria. Additional studies are needed to further assess the utility of measuring KIM-1 in the clinical setting.

Glomerular filtration rate and proteinuria: association with mortality and renal progression in a prospective cohort of a community-based elderly population

Limited prospective data are available on the importance of estimated glomerular filtration rate (GFR) and proteinuria in the prediction of all-cause mortality (ACM) in community-based elderly populations. We examined the relationship between GFR or proteinuria and ACM in 949 randomly selected community-dwelling elderly subjects (aged ≥65 years) over a 5-year period. A spot urine sample was used to measure proteinuria by the dipstick test, and GFR was estimated using the chronic kidney disease-epidemiology collaboration (CKD-EPI) equation. Information about mortality and causes of death was collected by direct enquiry with the subjects and from the national mortality data. Compared to subjects without proteinuria, those with proteinuria of grade ≥1+ had a 1.725-fold (1.134–2.625) higher risk of ACM. Compared to subjects with GFR ≥90 ml/min/1.73 m², those with GFR<45 ml/min/1.73 m² had a 2.357 -fold (1.170–4.750) higher risk for ACM. Among the 403 subjects included in the analysis of renal progression, the annual rate of GFR change during follow-up period was −0.52±2.35 ml/min/1.73 m²/year. The renal progression rate was 7.315-fold (1.841–29.071) higher in subjects with GFR<60 ml/min/1.73 m² than in those with GFR ≥60 ml/min/1.73 m². Among a community-dwelling elderly Korean population, decreased GFR of <45 ml/min/1.73 m² and proteinuria were independent risk factors for ACM.

CKD and cardiovascular disease in the Atherosclerosis Risk in Communities (ARIC) study: interactions with age, sex, and race

BACKGROUND

Estimated glomerular filtration rate (eGFR) and albuminuria are central for diagnosis, staging, and risk evaluation in chronic kidney disease (CKD). Universal thresholds regardless of age, sex, and race are recommended, but relatively little is known about how these demographic factors alter the relationship of eGFR and albuminuria to cardiovascular outcomes.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

11,060 whites and blacks aged 52-75 years in the Atherosclerosis Risk in Communities (ARIC) Study with median follow-up of 11.2 years.

PREDICTORS

eGFR by the CKD-EPI (CKD Epidemiology Collaboration) creatinine equation (reference, 95 mL/min/1.73 m(2)) and urinary albumin-creatinine ratio (ACR; reference, 5 mg/g).

OUTCOMES

Cardiovascular events (coronary disease, stroke, and heart failure) and all-cause mortality.

MEASUREMENTS

Adjusted HRs associated with eGFR and ACR in subgroups according to age, sex, and race.

RESULTS

Cardiovascular risk significantly increased at eGFR <70 mL/min/1.73 m(2) in all subgroups according to age (<65 vs ≥65 years), sex, and race (P for interaction >0.2 for these subgroups; eg, at eGFR of 30 mL/min/1.73 m(2), the adjusted HR was 2.19 [95% CI, 1.10-4.35] at age 52-64 years vs 2.23 [95% CI, 1.33-3.72] at age 65-75 years). Results were similar for mortality. Log(ACR) was associated linearly with cardiovascular risk without threshold effects in all subgroups, with some quantitative interactions. HRs according to ACR tended to be lower in men versus women (eg, at ACR of 40 mg/g, 1.18 [95% CI, 0.98-1.41] vs 1.77 [95% CI, 1.45-2.15]) and in the older versus younger population (1.24 [95% CI, 1.04-1.49] vs 1.73 [95% CI, 1.42-2.12]; P for interaction <0.01 for sex and age). Less evident interactions were observed for mortality.

LIMITATIONS

Single measurement of eGFR with creatinine and ACR and relatively narrow age range.

CONCLUSIONS

The associations of eGFR and ACR with cardiovascular events were largely similar, with some quantitative interactions, in age, sex, and racial subgroups, generally supporting universal thresholds of GFR and ACR for CKD definition/staging.

Urinary neutrophil gelatinase-associated lipocalin (NGAL) is associated with mortality in a community-based cohort of older Swedish men

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) indicates tubular kidney damage, neutrophil activation and possibly atherogenesis, however the prospective association between urinary NGAL (u-NGAL) and cardiovascular death in the community is not known.

METHODS

This study evaluates the association between urinary and serum NGAL and mortality in a Swedish population of 597 men aged 78 years. During the study (median follow-up 8.1 years) 261 men died, 90 of cardiovascular causes.

RESULTS

U-NGAL was associated with increased all-cause and cardiovascular mortality (HR 2.0 for quartile 4 vs. quartile 1, 95% CI 1.0-4.0, P < 0.05) in Cox regression models independently of cardiovascular risk factors, CRP and cystatin C estimated glomerular filtration rate (eGFRCysC) but not urinary Albumin (u-Alb). A combination of low eGFRCysC (≤60 mL/min), high u-Alb (≥3 mg/mmol Cr) and high u-NGAL (≥1.19 μg/mmol Cr) was associated with a 9-fold increased cardiovascular mortality (P < 0.001) and a 3-fold increased all-cause mortality (P < 0.001). Serum NGAL was associated with increased all-cause mortality risk independent of other cardiovascular risk factors (HR 1.4 for quartile 4 vs.1, 95% CI 1.0-1.9, P < 0.05) but not after adjustment with CRP, eGFRCysC or u-Alb.

CONCLUSION

This community study is the first to show that the tubular kidney biomarker u-NGAL associated with increased cardiovascular and all-cause mortality independent of cardiovascular risk factors and glomerular filtration. Additional research is needed to evaluate the utility of NGAL in clinical practice.

Combined association of creatinine, albuminuria, and cystatin C with all-cause mortality and cardiovascular and kidney outcomes

BACKGROUND

Estimated GFR by serum creatinine (eGFRcreatinine) is a pivotal measure of kidney function in clinical practice but can be affected by several non-GFR determinants, resulting in misclassification. Combining multiple kidney markers to predict risk is an area of substantial interest.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study followed 9489 adults from visit 4 (1996-1998) of the Atherosclerosis Risk in Communities Study for a median of 11.2 years, and assessed joint association of eGFRcreatinine, eGFRcystatin, and urinary albumin/creatinine ratio (ACR) with mortality, coronary heart disease, heart failure, AKI, and ESRD using Cox proportional hazards models. The predictive ability of ACR and eGFRcystatin beyond eGFRcreatinine was also investigated.

RESULTS

Lower eGFRcreatinine and eGFRcystatin as well as elevated ACR were independently associated with risk for all outcomes. eGFRcreatinine <60 was not associated with risk of mortality, coronary heart disease, or heart failure if eGFRcystatin ≥60 with ACR <30 mg/g compared with those with all three markers above CKD cutoffs (i.e., eGFRcystatin ≥60, eGFRcreatinine ≥60, and ACR<30), whereas risk association with kidney outcomes remained: Hazard ratio (95% confidence interval), 0.96 (0.66, 1.39) for mortality, 0.85 (0.55, 1.31) for coronary heart disease, 0.99 (0.60, 1.63) for heart failure, 1.61 (0.92, 2.82) for AKI, and 3.53 (1.06, 11.68) for ESRD. Adding ACR to the fully adjusted model with eGFRcreatinine or adding eGFRcystatin to both eGFRcreatinine and ACR improved risk classification for all outcomes (P ≤ 0.01).

CONCLUSIONS

eGFRcystatin can be a useful confirmatory marker in those with eGFRcreatinine <60 and whose ACR is <30 mg/g. This approach improves risk classification, and provides reassurance to a large group of individuals with eGFRcreatinine <60.

The predictive value of albuminuria for renal and nonrenal natural deaths over 14 years follow-up in a remote aboriginal community

BACKGROUND

Australian aboriginal people living in remote regions have extraordinary higher rates of mortality compared with other Australian ethnicities. Albuminuria marks the underlying renal disease. This study assessed the predictive value of albuminuria for nonrenal and renal deaths in a remote Australian aboriginal community over a follow-up period of >14 years.

METHODS

From 1992 to 1997, 85% of community members participated in a health screen, which included measurement of urine albumin/creatinine (ACR) levels. Deaths and dialysis initiations were recorded until 30 November 2010. The rates of natural nonrenal and renal deaths were assessed over a mean of 14 years in the 956 participants aged 18 years and over at baseline, and mortality associated with baseline levels of albuminuria (ACR ≥ 2.7 mg/mmol) was estimated.

RESULTS

There were 203 natural deaths; 70 were renal deaths and 133 were nonrenal deaths, including 60 cardiovascular disease (CVD) deaths. Higher baseline ACR predicted all categories of natural death, with no apparent lower threshold for effect. Baseline ACR ≥ 2.7 mg/mmol predicted a 3.3-fold increase in all natural deaths, a 2-fold increase in nonrenal deaths and a 1.7-fold increase in CVD deaths, after adjustment for other factors. Eighty-nine percent (62 out of 70) of renal deaths occurred in those with ACR ≥ 34 at baseline, with a 24-fold increase in risk. Albuminuria (ACR ≥ 2.7 mg/mmol) contributed to 66% of risk for all natural deaths over the interval.

CONCLUSIONS

Albuminuria was still a remarkable predictor for all-cause natural death over an average of 14 years follow-up interval in this aboriginal community.

Estimated glomerular filtration rate as an independent predictor of atherosclerotic vascular disease in older women

BACKGROUND

Estimated glomerular filtration rate (eGFR) levels have been shown to predict atherosclerotic vascular disease hospitalization and mortality. We sought to investigate the role of renal function in the prediction of 10-year atherosclerotic vascular hospitalization and deaths in an unselected population of elderly women and compared these predictions to Framingham equations.

METHODS

Complete 10-year verified mortality and hospitalization discharge records for atherosclerotic vascular disease were collected for a prospective study of 1,239 unselected female subject's ≥ 70 from the Calcium Intake Fracture Outcome Study (CAIFOS) with 10 years of follow-up. eGFR was compared to the current Framingham risk scores.

RESULTS

The eGFR at baseline using the Modification of Diet in Renal Disease Study (MDRD) equation was 65.2 ± 14.5 mL/min/1.73 m(2) and 66.3 ± 13.5 mL/min/1.73 m(2) using the Chronic Kidney Disease EPIdemiology (CKD-EPI) equation. Over 10 years 30% of participants sustained an ASVD hospitalization or death. For every standard deviation (SD) reduction in eGFR using MDRD the odds ratio (OR) for ASVD hospitalization and deaths increased by 1.34 (1.18-1.53), P < 0.00 and 1.31 (1.14-1.50), P < 0.001 in a model adjusted for Framingham 10-year general cardiovascular risk. Addition of eGFR by the MDRD equation to Framingham risk factors improved the net reclassification index by 5.9%, P = 0.018 and the integrated discrimination improvement by 0.010 ± 0.003, P < 0.001 Similar results were seen using the CKD-EPI equation.

CONCLUSION

Estimated glomerular filtration rate predicts ASVD outcomes independently of Framingham risk score predictions in elderly women and improves clinical prediction particularly of early ASVD.

The implications of anatomical and functional changes of the aging kidney: with an emphasis on the glomeruli

Aging is both a natural and inevitable biological process. With advancing age, the kidneys undergo anatomical and physiological changes that are not only the consequences of normal organ senescence but also of specific diseases (such as atherosclerosis or diabetes) that occur with greater frequency in older individuals. Disentangling these two processes, one pathologic and the other physiologic, is difficult. In this review we concentrate on the glomerular structural and functional alterations that accompany natural aging. We also analyze how these changes affect the identification of individuals of advancing age as having chronic kidney disease (CKD) and how these changes can influence prognosis for adverse outcomes, including all-cause mortality, end-stage renal disease, cardiovascular events and mortality, and acute kidney injury. This review describes important shortcomings and deficiencies with our current approach and understanding of CKD in the older and elderly adult.

The contribution of chronic kidney disease to the global burden of major noncommunicable diseases

Noncommunicable diseases (NCDs) are the most common causes of premature death and morbidity and have a major impact on health-care costs, productivity, and growth. Cardiovascular disease, cancer, diabetes, and chronic respiratory disease have been prioritized in the Global NCD Action Plan endorsed by the World Health Assembly, because they share behavioral risk factors amenable to public-health action and represent a major portion of the global NCD burden. Chronic kidney disease (CKD) is a key determinant of the poor health outcomes of major NCDs. CKD is associated with an eight- to tenfold increase in cardiovascular mortality and is a risk multiplier in patients with diabetes and hypertension. Milder CKD (often due to diabetes and hypertension) affects 5-7% of the world population and is more common in developing countries and disadvantaged and minority populations. Early detection and treatment of CKD using readily available, inexpensive therapies can slow or prevent progression to end-stage renal disease (ESRD). Interventions targeting CKD, particularly to reduce urine protein excretion, are efficacious, cost-effective methods of improving cardiovascular and renal outcomes, especially when applied to high-risk groups. Integration of these approaches within NCD programs could minimize the need for renal replacement therapy. Early detection and treatment of CKD can be implemented at minimal cost and will reduce the burden of ESRD, improve outcomes of diabetes and cardiovascular disease (including hypertension), and substantially reduce morbidity and mortality from NCDs. Prevention of CKD should be considered in planning and implementation of national NCD policy in the developed and developing world.