Relationships among renal function loss within the normal to mildly impaired range, arterial stiffness, inflammation, and oxidative stress

A cost-effective, machine learning-driven approach for screening arterial functional aging in a large-scale Chinese population

Introduction

An easily accessible and cost-free machine learning model based on prior probabilities of vascular aging enables an application to pinpoint high-risk populations before physical checks and optimize healthcare investment.

Methods

A dataset containing questionnaire responses and physical measurement parameters from 77,134 adults was extracted from the electronic records of the Health Management Center at the Third Xiangya Hospital. The least absolute shrinkage and selection operator and recursive feature elimination-Lightweight Gradient Elevator were employed to select features from a pool of potential covariates. The participants were randomly divided into training (70%) and test cohorts (30%). Four machine learning algorithms were applied to build the screening models for elevated arterial stiffness (EAS), and the performance of models was evaluated by calculating the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy.

Results

Fourteen easily accessible features were selected to construct the model, including "systolic blood pressure" (SBP), "age," "waist circumference," "history of hypertension," "sex," "exercise," "awareness of normal blood pressure," "eat fruit," "work intensity," "drink milk," "eat bean products," "smoking," "alcohol consumption," and "Irritableness." The extreme gradient boosting (XGBoost) model outperformed the other three models, achieving AUC values of 0.8722 and 0.8710 in the training and test sets, respectively. The most important five features are SBP, age, waist, history of hypertension, and sex.

Conclusion

The XGBoost model ideally assesses the prior probability of the current EAS in the general population. The integration of the model into primary care facilities has the potential to lower medical expenses and enhance the management of arterial aging.

Glycemia is associated with subclinical atherosclerosis through renal function in nondiabetic apparently healthy adults: a mediation analysis

The causative associations between glycemia and early alterations in renal and vascular function remain unclear. To examine the interplay among glycemia, renal function, and markers of subclinical atherosclerosis in apparently healthy subjects. Nondiabetic (30-60 years old) individuals (n = 205) without chronic kidney disease or cardiovascular disease were consecutively recruited from a cardiovascular prevention clinic. All subjects underwent arterial stiffness assessment by measuring the carotid-femoral pulse wave velocity (cfPWV). Glomerular filtration rate (GFR) was estimated by CKD-EPI equation. Study procedures were identical in the two visits (median follow-up 66 months). We employed structural equation modeling (SEM) analysis to investigate the directionality of associations. Baseline fasting plasma glucose (FPG) was independently and inversely associated with GFR (p = 0.008). GFR was significantly associated with cfPWV (p < 0.001) at baseline. By SEM analysis decreasing baseline GFR directly correlated with increasing cfPWV (p = 0.003) whereas FPG correlated with cfPWV indirectly through GFR (mediation) (P = 0.032). FPG did not mediate the effect of GFR on cfPWV (P = 0.768). SEM analysis of longitudinal data revealed bidirectional correlations between changes in FPG and GFR (P < 0.001). Alterations in GFR were directly related to changes in cfPWV (p < 0.001) whereas FPG only indirectly correlated with cfPWV through GFR changes (P = 0.002). In apparently healthy nondiabetic subjects, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status. These findings provide the first clinical evidence supporting the directionality between kidney function and glycemia in nondiabetic subjects leading to vascular dysfunction. In apparently healthy nondiabetic subjects, without cardiovascular disease or chronic kidney disease, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status.

The relationship of endothelial function and arterial stiffness with subclinical target organ damage in essential hypertension

This study aimed to explore whether brachial‐ankle pulse wave velocity (baPWV) and brachial artery flow‐mediated dilation (FMD) or the interaction of both parameters are associated with subclinical target organ damage (STOD) indices in patients with essential hypertension. A total of 4618 patients registered from January 2015 to October 2020 were included. baPWV and FMD were measured to evaluate arterial stiffness and endothelial dysfunction. Whereas left ventricular hypertrophy (LVH), urine albumin‐creatinine ratio (UACR), and carotid intima‐media thickness (CIMT) were obtained as STOD indicators. On multivariable logistic regression analysis with potential confounders, higher quartiles of baPWV and FMD were significantly associated with an increased risk of STOD. In patients <65 years of age, the odds ratio (OR) of LVH, UACR, and CIMT ≥.9 mm for the fourth versus the first quartile of baPWV were 1.765 (1.390–2.240), 2.832 (2.014–3.813), and 3.075 (2.315–4.084), respectively. In interaction analysis, an increase in baPWV shows a progressively higher risk of STOD across the quartiles of FMD. Also, the estimated absolute risks of LVH, UACR, and CIMT ≥.9 mm for the first to fourth quartile of baPWV increased from 1.88 to 2.75, 2.35 to 4.44, and 3.10 to 6.10, respectively, in patients grouped by FMD quartiles. The addition of baPWV to FMD slightly improved risk prediction for STOD. BaPWV and FMD were independently associated with an increased risk of STOD in patients with essential hypertension especially among patients <65 years of age. Patients with elevated baPWV and decreased FMD parameters are at increased risk of STOD.

Kidney Function and Aortic Stiffness, Pulsatility, and Endothelial Function in African Americans: The Jackson Heart Study

Rationale & Objective

The relation of vascular stiffness, endothelial function, and kidney function is incompletely elucidated in African Americans. Our hypothesis was that increased vascular stiffness and endothelial dysfunction are associated with low estimated glomerular filtration rate (eGFR) and albuminuria in African Americans.

Study Design

Cross-sectional cohort analysis of data from the Jackson Heart Study.

Settings & Patients

2,244 Jackson Heart Study participants (2012-2017 after Exam 3) who had undergone noninvasive hemodynamic assessment using arterial tonometry.

Predictors

Baseline carotid-femoral pulse wave velocity, pulsatile hemodynamics forward wave amplitude, and hyperemic brachial artery flow were measured. Reduced eGFR was defined as eGFR between 15 and 60 mL/min/1.73 m².

Outcomes

Prevalent albuminuria, urinary albumin-creatinine ratio.

Analytical Approach

2-sample t test for continuous variables and χ² test for categorical variables in addition to logistic and linear regression models to assess the risk for chronic kidney disease with each proposed hemodynamic variable.

Results

Among 2,244 participants, mean age was 66 ± 11 years and 64% were women. Reduced eGFR was present in 233 (10.4%), and elevated urinary albumin-creatinine ratio, in 232 (10.4%). In multivariable-adjusted analyses, higher carotid-femoral pulse wave velocity was associated with the presence of reduced eGFR (OR, 1.37 [95% CI, 1.08-1.75] per SD; P = 0.01) and with prevalent albuminuria (OR, 1.66 [95% CI, 1.32-2.11]; P < 0.001). Higher forward wave amplitude was significantly associated with prevalent albuminuria (OR, 1.37 [95% CI, 1.14-1.65]; P = 0.001).

Limitations

Cross-sectional analyses cannot inform causality.

Conclusions

Higher arterial stiffness and pulsatility are associated with higher odds of reduced eGFR in African Americans. Future studies should focus on whether improving arterial stiffness contributes to kidney protection in African Americans.

High Pulse Wave Velocity Is Associated With Decreased Macular Vessel Density in Normal-Tension Glaucoma

Purpose

To investigate the relationship between pulse wave velocity (PWV) and retinal vessel density (VD) measured by optical coherence tomography angiography (OCTA) in patients with normal-tension glaucoma (NTG).

Methods

This retrospective study included 103 patients with NTG and 109 healthy controls who underwent glaucoma examination and PWV measurements. Each group was classified into two subgroups according to a brachial-ankle PWV of 1400 cm/s. NTG was diagnosed when the maximum untreated intraocular pressure was < 21 mmHg on three repeated measurements obtained at different times in the presence of glaucomatous optic discs (neuroretinal rim thinning and excavation), peripapillary retinal nerve fiber layer defects, and glaucomatous visual field defects. Healthy controls did not have glaucomatous optic discs or visual field defects and exhibited normal retinal nerve fiber layer thickness. The interval between glaucoma examination and PWV measurements did not exceed six months. Univariate and multivariate logistic regression analyses were performed to identify factors associated with high PWV.

Results

PWV was higher in the NTG group than in the control group, while peripapillary VD and macular VD (mVD) were lower (all P < 0.05). Stepwise logistic regression analysis revealed that high PWV was significantly associated with age, mean arterial pressure (MAP), and mVD in the NTG group. Meanwhile, high PWV was significantly associated with age, MAP, and low-density lipoprotein cholesterol levels in healthy controls.

Conclusions

High PWV is associated with decreased mVD in NTG patients, suggesting that systemic arterial stiffness might be involved in the pathogenesis of NTG.

Metabolic healthy obesity is associated with higher incidence of mild decrease estimate glomerular rate in rural northeast Chinese

BACKGROUND

Metabolic healthy obesity (MHO), a phenotype of obesity, seems to be associated with a lower risk of cardiovascular disease. However, MHO has a close relationship with a higher incidence of metabolic syndrome and diabetes. This study aimed to investigate the prevalence of MHO at baseline, the changes in the obese metabolic phenotype at follow-up and the relationship of this phenotype with the incidence of mildly reduced estimated glomerular filtration rate (eGFR) in rural Northeast Chinese.

METHODS

The Chronic Kidney Disease Epidemiology (CKD-EPI) equation was used to calculate eGFR. A total of 4903 participants aged ≥35 years with eGFR > 90 ml/min/1.73 m² at baseline were enrolled and successfully followed. All participants completed the questionnaires, anthropometric measurements, and blood tests during baseline and follow-up. Mild renal dysfunction was defined as mildly reduced eGFR between 60 and 90 ml/min/1.73 m².

RESULTS

The prevalence of MHO was 20.0% at baseline (19.0% for women and 21.1% for men), which was secondary to metabolic abnormal obesity (MAO) (24.4, 27.2% for women and 21.5% for men). A total of 38.4% of women and 38.9% of men experienced phenotypic changes during follow-up. The cumulative incidence of mildly reduced eGFR in the MHO group was 20.1% (17.7% for women and 22.3% for men), which was also secondary to the incidence in the MAO group (20.8, 18.6% for women and 23.5% for men). After adjusting for age, current smoking, current drinking, chronic diseases, LDL-C, ALT, and AST, MHO was associated with a higher incidence of mildly reduced eGFR among women [OR (95% CI) =1.6 (1.2, 2.3)] and men [OR (95% CI) =1.6(1.2, 2.1)], whereas MAO was related to a higher incidence of mildly reduced eGFR among men only [OR (95% CI) =1.7 (1.3, 2.3)].

CONCLUSION

MHO was associated with a higher incidence of mildly reduced eGFR in both sexes; however, there was a specific relationship between MAO and mildly reduced eGFR in men only. Therefore, it is necessary to monitor kidney function among participants with both MHO and MAO.

State of the Art Review: Brachial-Ankle PWV

The brachial-ankle pulse wave velocity (brachial-ankle PWV), which is measured simply by wrapping pressure cuffs around the four extremities, is a simple marker to assess the stiffness of the medium- to large- sized arteries. The accuracy and reproducibility of its measurement have been confirmed to be acceptable. Risk factors for cardiovascular disease, especially advanced age and high blood pressure, are reported to be associated with an increase of the arterial stiffness. Furthermore, arterial stiffness might be involved in a vicious cycle with the development/progression of hypertension, diabetes mellitus and chronic kidney disease. Increase in the arterial stiffness is thought to contribute to the development of cardiovascular disease via pathophysiological abnormalities induced in the heart, brain, kidney, and also the arteries themselves. A recent independent participant data meta-analysis conducted in Japan demonstrated that the brachial-ankle PWV is a useful marker to predict future cardiovascular events in Japanese subjects without a previous history of cardiovascular disease, independent of the conventional model for the risk assessment. The cutoff point may be 16.0 m/s in individuals with a low risk of cardiovascular disease (CVD), and 18.0 m/s in individuals with a high risk of CVD and subjects with hypertension. In addition, the method of measurement of the brachial-ankle PWV can also be used to calculate the inter-arm systolic blood pressure difference and ankle-brachial pressure index, which are also useful markers for cardiovascular risk assessment.

Arterial stiffness evaluated by carotid-femoral pulse wave velocity increases the risk of chronic kidney disease in a Chinese population-based cohort

AIM

Chronic kidney disease (CKD) is an independent risk factor for cardiovascular disease. Although pulse wave velocity (PWV), which reflects arterial stiffness, was increased in subjects with CKD, little is known regarding whether arterial stiffness can increase the risk of CKD. To help clarify this we conducted a prospective cohort study to measure the association of arterial stiffness with CKD.

METHODS

A total of 7154 adults aged 54.8 ± 10.6 years undergoing physical examinations without CKD at baseline were enrolled. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cfPWV). CKD was defined as decreased estimated glomerular filtration rate (eGFR < 60 mL/min per 1.73 m² ) or presence of proteinuria (urine protein ≥ 1+) assessed using a repeated dipstick method.

RESULTS

During 3 years of follow-up, 167 (2.3%) patients developed CKD, 101 (1.4%) patients with proteinuria and 68 (1.0%) patients with decreased eGFR. After adjusted for potential confounders, either cfPWV (per 1 m/s increase) or the highest quartile of cfPWV (increased cfPWV) was independently associated with increased risk of proteinuria, with a fully adjusted OR of 1.15 (95% CI, 1.07 to 1.23) and 1.93 (95% CI, 1.15 to 3.25), respectively. By contrast, neither cfPWV (per 1 m/s increase) nor increased cfPWV was associated with decreased eGFR in the multivariable logistic regression analysis.

CONCLUSIONS

The study revealed that arterial stiffness increases the risk of proteinuria. This suggests that vascular stiffness could be considered as a target for delaying the development of CKD.

High Ambulatory Arterial Stiffness Index Is an Independent Risk Factor for Rapid Age-Related Glomerular Filtration Rate Decline in the General Middle-Aged Population

Arterial stiffness is a risk factor for cardiovascular and chronic kidney disease. However, the role of arterial stiffness as a predictor of the age-related glomerular filtration rate (GFR) decline in the general population remains unresolved because of difficulty in measuring GFR with sufficient precision in epidemiological studies. The ambulatory arterial stiffness index (AASI) is a proposed indicator of arterial stiffness easily calculated from ambulatory blood pressure. We investigated whether AASI could predict GFR decline measured as iohexol clearance in the general population. We calculated AASI from baseline ambulatory blood pressure and measured the iohexol clearance at baseline and follow-up in the RENIS-FU study (Renal Iohexol Clearance Survey Follow-Up). AASI was defined as 1 minus the regression slope of the diastolic blood pressure measurement over the systolic blood pressure measurement for each patient. The RENIS cohort included a representative sample of the general middle-aged population without baseline diabetes mellitus, cardiovascular disease, or kidney disease (n=1608). The participant age was 50 to 62 years old at baseline, and the median observation time was 5.6 years. The mean (SD) of the GFR decline rate was 0.95 mL/min per year (2.23) and that of the AASI was 0.38 mL/min per year (0.13). Baseline ambulatory blood pressure or the night/day systolic or diastolic ambulatory blood pressure ratios were not associated with GFR decline. In multivariable-adjusted linear mixed regression analysis, 1 SD of increase in the baseline AASI was associated with a 0.14 mL/min per year (95% confidence interval, -0.26 to -0.02) steeper GFR decline. We conclude that the AASI is an independent risk factor for accelerated age-related GFR decline in the general middle-aged population.

Diagnostic and therapeutic problems of isolated systolic hypertension

Prevalence of isolated systolic hypertension increases with age, due to progressive elevation of SBP, and is a major risk factor for cardiovascular morbidity and mortality. Extensive research has shown that lowering SBP improves cardiovascular outcomes in patients with isolated systolic hypertension, yet SBP control rates remain largely inadequate regardless of antihypertensive treatment. Arterial stiffness is a major determinant of elevated SBP resulting from structural changes in the vascular system, mediated by neurohormonal alterations that occur with vascular ageing. Clinical data have demonstrated an independent association between arterial stiffness and cardiovascular outcomes. Therefore, arterial stiffness has the potential to be an important therapeutic target in the management of isolated systolic hypertension. Current antihypertensive treatments have limited effects on arterial stiffness, so the development of new treatments addressing neurohormonal alterations central to vascular ageing is important. Such therapies may represent effective strategies in the future management of SBP.

Aortic stiffness and kidney disease in an elderly population

BACKGROUND/AIMS

The causes of chronic kidney disease (CKD) in older people are not well understood. Aortic stiffness increases with age and results in the transmission of increased pulsatility into the kidney microvasculature, potentially contributing to CKD in older populations.

METHODS

We utilized data from the Age, Gene/Environment, Susceptibility-Reykjavik Study, a community-based prospective cohort study of cardiovascular disease (CVD) in Iceland. The relationship of carotid pulse pressure (CPP) and carotid-femoral pulse wave velocity (CFPWV) with estimated glomerular filtration rate (eGFR) based on creatinine and cystatin C and urine albumin-creatinine ratio (ACR) was assessed using linear regression, adjusting for demographics and CVD risk factors.

RESULTS

940 participants (mean (SD) age 75.8 (4.7) years, mean (SD) CFPWV 12.9 (4.2) m/s, mean (SD) CPP 69 (21) mm Hg, mean (SD) eGFR 68 (16) ml/min/1.73 m(2), and median (IQR) ACR 3 (2-6) mg/g) were included in this study. At CPP greater than 85 mm Hg, a higher CPP was associated with a lower eGFR in unadjusted analyses but not after adjustment. CPP was significantly associated with a higher ACR in fully adjusted models (β (95% CI) = 0.14 (0.03, 0.24) ln mg/g per SD). Higher CFPWV was associated with lower eGFR and higher ACR in unadjusted analyses but not after adjustment.

CONCLUSION

Greater aortic stiffness may be associated with modestly higher levels of albuminuria in the elderly. The association between aortic stiffness and lower eGFR may be confounded by age and CVD risk factors.

Arterial stiffness and increased cardiovascular risk in chronic kidney disease

Chronic kidney disease (CKD) is a global public health problem. Cardiovascular disease (CVD) is a common comorbidity and a major cause of mortality in CKD population. While CVD-related mortality is relatively uncommon in young population, it accounts for most deaths in young CKD adults. There are numerous risk factors for CVD in CKD patients including conventional (hypertension, diabetes, dyslipidemia) and nonconventional (oxidative stress, inflammation, anemia, mineral metabolism disorder) factors. Recent studies have placed great emphasis on the association of arterial stiffness (AS) and CVD. AS is traditionally known as an aging marker of the artery; however, increased AS is observed in young and even in pediatric CKD patients; it is also shown that AS progresses in consistent with kidney function decline. Unparallel AS in young CKD population and excessive risk of CVD in young CKD adults show an indication that AS probably offers one of the underlying mechanisms for linking CKD and CVD. AS in CKD patients has multifactorial causes. Comorbidities such as hypertension, diabetes, dyslipidemia, and mineral metabolism disorder which are risk factors for CVD also show great contribution to AS in CKD patients. Increased systolic blood pressure and decreased diastolic blood pressure resulting from AS cause elevated ventricular afterload, lead to impaired coronary perfusion, myocardial ischemia, and ventricular hypertrophy, and consequently develop into CVD event. In this review, we summarized the role of AS in CKD and CVD, aiming to explore the linkage of AS between CKD and CVD.

Clinical Considerations for the Association between Vascular Damage and Chronic Kidney Disease

Chronic kidney disease (CKD) is an independent risk factor for cardiovascular disease. Recently, noninvasive and simple morphological and functional methods have been introduced to assess atherosclerotic vascular damage. This review describes the association of CKD with vascular damage as assessed by these methods. Carotid intima-media thickness (IMT) and coronary artery calcium score (CACS) are morphological parameters of vascular damage, and an ankle-brachial index (ABI) <0.90 suggests the presence of peripheral arterial disease (i.e., it represents advanced atherosclerosis). Several prospective studies have demonstrated that CKD is a risk factor for an increased IMT, an increased CACS and a decreased ABI. While it has not been clarified whether measuring the IMT or CACS might be useful to predict the progression of renal function decline, a reduced ABI has been demonstrated as a predictor of accelerated renal function decline. On the other hand, pulse wave velocity (PWV) is a marker of arterial stiffness rather than atherosclerosis, reflecting functional abnormalities caused by vascular damage, and moderate-to-severe CKD may be a risk factor for the progression of arterial stiffness. The measurement of functional markers, especially of PWV or pulse pressure, has been demonstrated to be useful to predict the rate of progression of renal function decline. Thus, renal dysfunction and atherogenic states may be components of a vicious cycle, and vascular function abnormalities associated with atherosclerosis may accelerate this cycle. As the next step, we propose to examine whether improvement of vascular function abnormalities can interrupt this vicious cycle.

Relationship between red blood cell distribution width and early-stage renal function damage in patients with essential hypertension

BACKGROUND

Red cell distribution (RDW) has been suggested to be associated with cardiovascular mortality and mortality. However, few studies have yet investigated the possible association between RDW and early-stage renal function damage in patients with primary hypertension without receiving drug treatment. Accordingly, the aim of the present study was to evaluate early-stage renal function status in patients with RDW levels.

RESULTS

The study included 513 primary hypertension patients (319 men and 194 women) without receiving drug treatment. Significant positive correlation was observed between albumin-to-creatinine ratio (ACR) and RDW in hypertensive patients (r = 0.531, P < 0.001). In multivariate line regression analysis, night-time SBP (B = 0.042, P < 0.001), ACR (B = 0.005, P < 0.001), and uric acid (B = 0.001, P = 0.022) were positive predictors of RDW independent of age, sex, hemoglobin, and other indexes, whereas daytime SBP (B = -0.019, P < 0.001) was inversely associated with RDW. The receiver operating characteristics curves (ROC) explored the relationship between renal function status and RDW, estimated glomerular filtration rate (eGFR), serum creatinine, and high-sensitivity C-reactive protein. The area under the curve was 0.81 (95% CI: 0.77-0.85; P < 0.001), 0.45 (95% CI: 0.39-0.50; P = 0.049), 0.49 (95% CI: 0.43-0.54; P = 0.583), and 0.49 (95% CI: 0.44-0.55; P = 0.811), respectively. Using a cutoff point of 12.8, the RDW predicted renal function status (ACR) with a sensitivity of 76% and a specificity of 70%.

CONCLUSION

RDW, as an easy and quick measurable index, can predict early-stage renal function damage in essential hypertensive patients without receiving drug treatment.

Association of renal function with vascular stiffness in older adults: the Rotterdam study

BACKGROUND

arterial stiffening is a marker of vascular ageing and an independent risk factor for cardiovascular disease. A potential mechanism linking cardiovascular disease to chronic kidney disease might be the change in arterial elasticity. We aim to determine the association between renal function and arterial stiffness in older subjects.

DESIGN

cross-sectional study.

SETTING

Rotterdam study, a population-based cohort study.

SUBJECTS

we included 3,279 subjects from 1997 to 1999 with a mean age of 71.9 years.

METHODS

estimation of glomerular filtration rate (eGFR) was used to assess renal function. Aortic pulse wave velocity (PWV) and carotid distensibility coefficient were used as measures of arterial stiffness.

RESULTS

each standard deviation increase in eGFR, adjusting for age and sex, was associated with 0.14 m/s lower PWV [95% confidence interval (CI): -0.23, -0.05]. Further adjustments for socio-demographic and cardiovascular risk factors did not change the association (β: -0.16 m/s; 95% CI: -0.26, -0.06). There was a linear association between mean values of PWV and quartiles of glomerular filtration rate (P for trend = 0.006). There was no association between decreased renal function and carotid distensibility. There was no statistical difference in the strength of the association between renal function and PWV in subgroups of participants with and without cardiovascular risk factors.

CONCLUSIONS

in this large population-based study of elderly subjects, our findings suggest that renal impairment is associated with aortic stiffness. This association is independent of cardiovascular risk factors.

Circulating bilirubin and defense against kidney disease and cardiovascular mortality: mechanisms contributing to protection in clinical investigations

Unconjugated bilirubin is an endogenous circulating antioxidant, bound to albumin, and therefore is retained in the vascular compartment. Bilirubin has well-documented neurotoxic effects in infants; however, current evidence indicates mildly elevated bilirubin is associated with protection from cardiovascular disease and all-cause mortality in adults. Recent clinical studies show mildly elevated bilirubin is associated with protection from kidney damage and dysfunction, in addition to cardiovascular events and all-cause mortality in patients undergoing hemodialysis. This is the first review to examine the clinical evidence and summarize the potential mechanisms of action that link bilirubin to protection from kidney damage, subsequent kidney failure, and dialysis-related mortality. With this understanding, it is hoped that new therapies will be developed to prevent renal dysfunction and mortality from cardiovascular disease in at-risk individuals.

Association of glomerular filtration rate with arterial stiffness in Chinese women with normal to mildly impaired renal function

Objective

Both decreased glomerular filtration rate (GFR) and arterial stiffness were considered as risk factors for atherosclerosis. Previous studies have suggested the association between central arterial stiffness and the degree of GFR loss. Whether decreased GFR contributes to peripheral artery stiffness remains controversial. Moreover, data analyzed from a cohort of Chinese women are rare. Our aim was to explore the relationship between GFR and regional arterial stiffness in Chinese women.

Methods

In this cross-sectional study, we randomly recruited 1131 adult women residents with GFR ≥ 60 mL/min per 1.73 m² estimated by the Chinese Modification of Diet in Renal Disease equation from three large communities. Central and peripheral arterial stiffness were estimated simultaneously by measuring carotid-femoral pulse wave velocity (PWVcf) and carotid-radial PWV (PWVcr) using a validated automatic device. Augmentation Index at heart rate 75 beats/minutes (AIx-75) was measured by pulse wave analysis as a composite parameter reflecting both large and distal arterial properties.

Results

The mean estimated GFR (eGFR) of the study group was 100.05 ± 23.26 mL/minute per 1.73 m². Subjects were grouped by tertiles of eGFR level. PWVcf and AIx-75 increased ongoing from the top to the bottom eGFR tertile, while the values of PWVcr were comparable. Both univariate Pearson correlations and multiple stepwise regression analyses showed that eGFR significantly correlated to PWVcf, but not to PWVcr and AIx-75.

Conclusions

In Chinese women with normal to mildly impaired renal function, decreased eGFR affected carotid-to-femoral rather than carotid-to-radial stiffening. This provides rational to conduct future prospective studies to investigate predictors of atherosclerosis in this population.

Arterial stiffness is associated with incident albuminuria and decreased glomerular filtration rate in type 2 diabetic patients

OBJECTIVE

To investigate the association between aortic stiffness and incident albuminuria and the decline in estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We investigated 461 Japanese type 2 diabetic patients, comprising 199 women and 262 men, with a mean age of 59 ± 11 years. Patients were divided into two groups according to the median value of carotid-femoral pulse wave velocity (cf-PWV), which was used to evaluate aortic stiffness. The end point was defined as the transition from normo- to microalbuminuria or micro- to macroalbuminuria. The Cox proportional hazard model was used to calculate the hazard ratio (HR) and 95% CI. The correlation between cf-PWV and rate of change in eGFR was also determined by linear regression analysis.

RESULTS

The baseline mean (± SD) cf-PWV was 9.6 ± 2.4 m/s. During a median follow-up period of 5.9 years (range 0.3-8.6), progression of albuminuria was observed in 85 patients. The 5-year cumulative incidence of the end point in patients with cf-PWV below and above the median was 8.5 and 19.4%, respectively (P = 0.002, log-rank test). cf-PWV was significantly associated with incident albuminuria (HR 1.23, 95% CI 1.13-1.33, P < 0.001) by multivariate Cox regression analysis. A significant association between cf-PWV and annual change in eGFR was also suggested by multiple linear regression analysis (standardized estimate -0.095, P = 0.031).

CONCLUSIONS

Aortic stiffness is associated with incident albuminuria and the rate of decline in glomerular filtration rate in type 2 diabetic patients.

Association of pulse pressure, arterial elasticity, and endothelial function with kidney function decline among adults with estimated GFR >60 mL/min/1.73 m(2): the Multi-Ethnic Study of Atherosclerosis (MESA)

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

Multi-Ethnic Study of Atherosclerosis (MESA) participants with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) with follow-up of 5 years.

PREDICTORS

Pulse pressure, small (SAE) and large arterial elasticity (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 assessed by eGFR based on serum creatinine (eGFR(SCr)) and cystatin C (eGFR(SCysC)).

RESULTS

For 4,853 adults, higher pulse pressure and lower SAE and LAE had independent and linear associations with faster rates of kidney function decline. Compared with persons with pulse pressure of 40-50 mm Hg, eGFR(SCysC) declines were 0.29 (P = 0.006), 0.56 (P < 0.001), and 0.91 (P < 0.001) mL/min/1.73 m(2)/y faster in persons with pulse pressure of 50-60, 60-70, and >70 mm Hg, respectively. Compared with the highest quartile of SAE (most elastic), eGFR(SCysC) declines were 0.26 (P = 0.009), 0.35 (P = 0.001), and 0.70 (P < 0.001) mL/min/1.73 m(2)/y faster for the second, third, and fourth quartiles, respectively. For LAE, compared with the highest quartile, eGFR(SCysC) declines were 0.28 (P = 0.004), 0.58 (P < 0.001), and 0.83 (P < 0.001) mL/min/1.73 m(2)/y faster for each decreasing quartile of LAE. Findings were similar for eGFR(SCr). In contrast, for 2,997 adults with flow-mediated dilation and kidney function measures, flow-mediated dilation was not associated significantly with kidney function decline. For every 1-standard deviation greater flow-mediated dilation, eGFR(SCysC) and eGFR(SCr) changed by 0.05 (P = 0.3) and 0.06 mL/min/1.73 m(2)/y (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 associated linearly and independently with faster kidney function decline in persons with eGFR ≥60 mL/min/1.73 m(2). Future studies should investigate whether treatments to decrease the stiffness of large and small arteries may slow the rate of kidney function loss.

Augmentation pressure and subendocardial viability ratio are associated with microalbuminuria and with poor renal function in type 1 diabetes

In this report we explore the hypothesis that arterial stiffness indices, which predict cardiovascular disease, might also correlate with microalbuminuria (MA) in type 1 diabetes (T1D), and thus have potential for risk assessment. Three pulse wave analysis (PWA) indices, measured using the SphygmoCor device, were evaluated on 144 participants with childhood-onset T1D. These variables, augmentation index (AIx), augmentation pressure (AP) and subendocardial viability ratio (SEVR, an estimate of myocardial perfusion) (an estimate of myocardial perfusion), were each analysed cross-sectionally in relation to both prevalent MA (defined as albuminuria excretion rate (AER) = 20-199 microg/min) and renal function (assessed by both eGFR and serum cystatin C). AP and SEVR were each univariately associated with AER, estimated glomerular filtration rate (eGFR) and cystatin C. Lower SEVR was also independently related to the presence of MA and degree of albuminuria within normo- and microalbuminuric participants. SEVR, not AP, was independently and negatively associated with both measures of renal function. SEVR is a better predictor of AER than brachial blood pressure measures in those without clinical proteinuria, indicating a potential use for PWA in the early detection of individuals at risk for cardiovascular and renal complications of T1D.

Arterial stiffness in mild-to-moderate CKD

Whether arterial stiffness correlates with mild-to-moderate CKD and albuminuria in the community is unclear. We studied the association between arterial stiffness and mild-to-moderate CKD and albuminuria in the Framingham Heart Study. CKD was present in 6.7% (181 of 2682) of participants and microalbuminuria was present in 8.2% (479 of 5818). The measures of arterial stiffness were the carotid femoral pulse wave velocity, forward pressure wave amplitude, central pulse pressure, augmentation pressure, augmentation index, and mean arterial pressure. In cross-sectional analyses, arterial stiffness did not associate with CKD (defined by estimated GFR <60 ml/min/1.73 m(2)) in either age- and gender-adjusted or multivariable-adjusted linear regression models. Carotid femoral pulse wave velocity associated with both urinary albumin-to-creatinine ratio and microalbuminuria (P < 0.0001 after multivariable adjustment). In longitudinal analyses, we used logistic regression models to examine the associations between baseline arterial stiffness measures (exposure variables) and incident CKD or microalbuminuria (n = 1675 for CKD analyses and n = 1252 for microalbuminuria analyses). Baseline arterial measures did not associate with incident CKD or incident microalbuminuria. In summary, arterial stiffness correlates with albuminuria but not with mild-to-moderate CKD.

Dietary protein safety and resistance exercise: what do we really know?

Resistance trainers continue to receive mixed messages about the safety of purposely seeking ample dietary protein in their quest for stimulating protein synthesis, improving performance, or maintaining health. Despite protein's lay popularity and the routinely high intakes exhibited by strength athletes, liberal and purposeful protein consumption is often maligned by "experts". University textbooks, instructors, and various forms of literature from personal training groups and athletic organizations continue to use dissuasive language surrounding dietary protein. Due to the widely known health benefits of dietary protein and a growing body of evidence on its safety profile, this is unfortunate. In response, researchers have critiqued unfounded educational messages. As a recent summarizing example, the International Society of Sports Nutrition (ISSN) Position Stand: Protein and Exercise reviewed general literature on renal and bone health. The concluding remark that "Concerns that protein intake within this range [1.4 – 2.0 g/kg body weight per day] is unhealthy are unfounded in healthy, exercising individuals." was based largely upon data from non-athletes due to "a lack of scientific evidence". Future studies were deemed necessary. This assessment is not unique in the scientific literature. Investigators continue to cite controversy, debate, and the lack of direct evidence that allows it. This review discusses the few existing safety studies done specific to athletes and calls for protein research specific to resistance trainers. Population-specific, long term data will be necessary for effective education in dietetics textbooks and from sports governing bodies.

Review: New techniques for assessment of vascular function

The noninvasive measurement of hemodynamic variables associated with hypertension and cardiovascular disease processes needs to be recognized as a viable adjunct to clinical practice. This review traces the history of the inception and development of noninvasive measurement of hemodynamic variable. It then identifies well established, useful, and available devices, and then notes clinical studies verifying the clinical relevance of these measurements. Given the need to intervene earlier in the course of cardiovascular disease processes, tools are needed to assist the medical team to evaluate, prognosticate, and guide their patient's therapy correctly. It is the goal of this review to heighten the awareness and enhance and encourage the implementation of these devices in our armamentarium for the betterment of our patient's health.