Association of kidney function and albuminuria with prevalent and incident hypertension: the Atherosclerosis Risk in Communities (ARIC) study

Combined and mediating effects of remnant cholesterol and renal function on hypertension risk in Chinese middle-aged and elderly people

Background

Emerging evidence indicates a potential correlation between remnant cholesterol (RC) and the development of vascular damage and hypertension. Nevertheless, the precise relationship between RC and hypertension in relation to renal function remains uncertain. The objective of this investigation was to employ a cohort design to evaluate the intricate correlation between RC and renal function in relation to hypertension.

Methods

The present investigation utilized data from the China Health and Retirement Longitudinal Study (CHARLS), encompassing a total of 5,109 participants, for comprehensive data analysis and examination. Cox regression analysis was employed to examine the interplay among RC, renal function, and hypertension within the context of this research study. This study utilized restricted cubic spline (RCS) analysis to elucidate the interaction between RC, renal function, and hypertension, specifically examining the mediating role of renal function in the RC-hypertension nexus. Furthermore, we employed mediation analysis to investigate the potential mediating role of renal function in the association between RC and hypertension.

Results

After a 9-year follow-up period, the incidence of hypertension in the population under investigation was observed to be 19.01%. The Kaplan-Meier curves demonstrated a notable and statistically significant elevation in the prevalence of hypertension within the subgroup characterized by higher RC and impaired renal function (P <0.001). However, in Cox regression analyses, the risk of developing hypertension was significantly higher (P <0.05) in those with high RC and high estimated glomerular filtration rate (eGFR), and those with high RC and low eGFR, compared with those with low RC and high eGFR, after adjusting for confounders. The analysis of RCS demonstrated a significant positive linear correlation between baseline RC and the prevalence of hypertension. Additionally, there was a notable negative linear correlation observed between eGFR levels and the prevalence of hypertension. RC and eGFR did not interact with any of the subgroup variables. eGFR lowering mediated 6% of the associations between RC and hypertension.

Conclusion

The findings of this study unveiled a substantial correlation between elevated RC, diminished eGFR levels, and the risk of developing hypertension. In addition, renal function may mediate the correlation between RC and hypertension risk.

Ultra-Processed Food Consumption and Risk of Incident Hypertension in US Middle-Aged Adults

BACKGROUND

Consumption of ultra-processed food, which is manufactured food that is high in additives and sparse in intact foods, is adversely associated with cardiovascular health, primarily in non-US study populations. We aimed to estimate the association between ultra-processed food consumption and incident hypertension in middle-aged adults in the United States.

METHODS AND RESULTS

We included 8923 ARIC (Atherosclerosis Risk in Communities) study participants who were hypertension free at baseline and had complete dietary, covariate, and hypertension data from visit 1 (1987-1989). Over a median (25th, 75th percentile) follow-up of 13 (6-21) years, 79% of participants developed hypertension. Participants in the highest quartile of ultra-processed food consumption had 15% higher risk of incident hypertension than those in the lowest quartile (hazard ratio [HR], 1.15 [95% CI, 1.08-1.23]). Participants in the highest quartile of consumption of sugar-sweetened beverages, red and processed meat, and margarine had 16% (HR, 1.16 [95% CI, 1.08-1.24]; p-trend <0.001), 10% (HR, 1.10 [95% CI, 1.03-1.19]; P trend = 0.005), and 6% (HR, 1.06 [95% CI, 0.99, 1.45]; P trend = 0.045) higher risk of incident hypertension, respectively, when compared with the lowest quartiles of consumption. Each additional serving of minimally or unprocessed food was associated with a 2% lower risk of incident hypertension (HR, 0.98 [95% CI, 0.98, 0.99], P<0.001).

CONCLUSIONS

High consumption of ultra-processed foods, specifically of sugar-sweetened beverages, red and processed meat, and margarine, was associated with a higher incidence of hypertension, whereas minimally or unprocessed food consumption was associated with lower hypertension risk.

Tumor necrosis factor-alpha mediates the negative association between telomere length and kidney dysfunction

Aim/hypothesis: The relationship between peripheral blood leukocyte telomere length (LTL) and kidney dysfunction, especially in people with hypertension, remains unclear. No clinical study has explored the role of inflammation and oxidative stress in the relationship between LTL and kidney dysfunction. Therefore, we examined the relationship between baseline LTL and albuminuria progression and/or rapid renal function decline in Chinese patients with or without hypertension and investigated whether inflammation and oxidative stress played a mediating role in this relationship. Methods: We conducted a prospective study including 262 patients in a 7-year follow-up period from 2014 to 2021. Data on LTL, inflammation, oxidative markers, renal function, and urine protein levels were assessed. Kidney dysfunction was defined as either albuminuria progression, rapid decline in renal function, or the composite endpoint (albuminuria progression and rapid decline in renal function). Logistic regression and simple mediation models were used for the analysis. Results: In this cohort (mean age, 54.3±9.7 years; follow-up period, 5.9±1.1 years), 42(16.0%), 21(8.0%), and 59(22.5%) patients developed albuminuria progression, rapid eGFR decline, and the composite endpoint of kidney dysfunction, respectively. Logistic regression analysis showed that each standard deviation decrease of baseline LTL and the lower quartile (Q) of baseline LTL were significantly correlated with an increased risk of rapid decline in renal function (OR=1.83 [95% CI 1.07, 3.27] per 1SD, P=0.03; OR=7.57 [95% CI 1.25, 145.88] for Q1 vs. Q4, P for trend=0.031); and the composite endpoint of kidney dysfunction (OR=1.37 [95% CI 0.97, 1.96] per 1SD, borderline positive P=0.072; OR=2.96[95% CI 1.15, 8.2] for Q1 vs. Q4, P for trend=0.036). The mediating analysis showed that tumor necrosis factor (TNF)-a partly mediated the relationship between LTL and rapid decline in renal function (direct effect: β=0.046 95%CI [0.006, 0.090],P=0.02; indirect effect: β=0.013 95%CI [0.003, 0.020]), and the mediating proportion was 22.4%.In subgroup analyses, LTL was inversely associated with rapid decline in renal function or the composite endpoint of kidney dysfunction only in patients with hypertension (OR=49.07[3.72,211.12] vs.1.32[0.69,2.58] per 1SD, P for interaction=0.045;OR=3.10 [1.48, 7.52] vs.1.08[0.92,1.63] per 1SD, P for interaction=0.036). Conclusion: Baseline LTL could independently predict kidney dysfunction at follow-up, especially in participants with hypertension. TNF-a partially mediated the negative association between LTL and kidney dysfunction.

Clonal Hematopoiesis of Indeterminate Potential and Kidney Function Decline in the General Population

RATIONALE & OBJECTIVE

Clonal hematopoiesis of indeterminate potential (CHIP), defined by the age-related ontogenesis of expanded leukemogenic variants indicative of a genetically distinct clonal leukocyte population, is associated with risk of hematologic malignancy and cardiovascular disease. In experimental models, recapitulation of CHIP promotes kidney interstitial fibrosis with direct tissue infiltration of donor macrophages. We tested the hypothesis that CHIP is associated with kidney function decline in the general population.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

12,004 individuals from 3 community-based cohorts in the TOPMed Consortium.

EXPOSURE

CHIP status from whole-genome sequences obtained from DNA extracted from peripheral blood.

OUTCOME

Risk of 30% decline in estimated glomerular filtration rate (eGFR) and percent eGFR decline per year during the follow-up period.

ANALYTICAL APPROACH

Cox proportional hazards models for 30% eGFR decline end point and generalized estimating equations for annualized relative change in eGFR with meta-analysis. Study-specific estimates were combined using fixed-effect meta-analysis.

RESULTS

The median baseline eGFR was 84mL/min/1.73m2. The prevalence of CHIP was 6.6%, 9.0%, and 12.2% in persons aged 50-60, 60-70, and>70 years, respectively. Over a median follow-up period of 8 years, for the 30% eGFR outcome 205 events occurred among 1,002 CHIP carriers (2.1 events per 100 person-years) and 2,041 events in persons without CHIP (1.7 events per 100 person-years). In meta-analysis, CHIP was associated with greater risk of a 30% eGFR decline (17% [95% CI, 1%-36%] higher; P=0.04). Differences were not observed between those with baseline eGFR above or below 60mL/min/1.73m2, of age above or below 60 years, or with or without diabetes.

LIMITATIONS

Small number of participants with moderate-to-advanced kidney disease and restricted set of CHIP driver variants.

CONCLUSIONS

We report an association between CHIP and eGFR decline in 3 general population cohorts without known kidney disease. Further studies are needed to investigate this novel condition and its potential impact among individuals with overt kidney disease.

Urine albumin-to-creatinine ratio within the normal range and risk of hypertension in the general population: A meta-analysis

Inconsistent findings on the association between urine albumin‐to‐creatinine ratio (UACR) and risk of hypertension have been reported. This meta‐analysis sought to evaluate the association between the elevated level of UACR within the normal range and incident hypertension in the general population. We comprehensively searched PubMed and Embase databases until July 31, 2020. All longitudinal observational studies that assessed the association of elevated baseline level of UACR within the normal range with incident hypertension in the general population were included. The predictive value was estimated by pooling risk ratio (RR) with 95% confidence intervals (CI) for the highest versus the lowest category of UACR level. Nine articles (10 studies) involving 27 771 individuals were identified and analyzed. When compared with the lowest category of UACR, individuals with the highest UACR had a 1.75‐fold (RR 1.75; 95% CI 1.47–2.09; p < .001) higher risk of hypertension in a random effect model. Gender‐specific analysis indicated that the impact of UACR on the development of hypertension seemed to be stronger in women (RR 2.47; 95% CI 1.10–5.55; p = .029) than in men (RR 1.88; 95% CI 1.35–2.61; p < .001). An increased UACR within the normal range is independently associated with a higher risk of hypertension in the general population. Baseline UACR can be served as a predictor of incident hypertension in the general population.

A bidirectional Mendelian randomization study supports causal effects of kidney function on blood pressure

Blood pressure and kidney function have a bidirectional relation. Hypertension has long been considered as a risk factor for kidney function decline. However, whether intensive blood pressure control could promote kidney health has been uncertain. The kidney is known to have a major role in affecting blood pressure through sodium extraction and regulating electrolyte balance. This bidirectional relation makes causal inference between these two traits difficult. Therefore, to examine the causal relations between these two traits, we performed two-sample Mendelian randomization analyses using summary statistics of large-scale genome-wide association studies. We selected genetic instruments more likely to be specific for kidney function using meta-analyses of complementary kidney function biomarkers (glomerular filtration rate estimated from serum creatinine [eGFRcr], and blood urea nitrogen from the CKDGen Consortium). Systolic and diastolic blood pressure summary statistics were from the International Consortium for Blood Pressure and UK Biobank. Significant evidence supported the causal effects of higher kidney function on lower blood pressure. Based on the mode-based Mendelian randomization method, the effect estimates for one standard deviation (SD) higher in log-transformed eGFRcr was -0.17 SD unit (95 % confidence interval: -0.09 to -0.24) in systolic blood pressure and -0.15 SD unit (95% confidence interval: -0.07 to -0.22) in diastolic blood pressure. In contrast, the causal effects of blood pressure on kidney function were not statistically significant. Thus, our results support causal effects of higher kidney function on lower blood pressure and suggest preventing kidney function decline can reduce the public health burden of hypertension.

Evidence for a Causal Role of the SH2B3-β2M Axis in Blood Pressure Regulation

Genetic variants at SH2B3 are associated with blood pressure and circulating β₂M (β-2 microglobulin), a well-characterized kidney filtration biomarker. We hypothesize that circulating β₂M is an independent risk predictor of hypertension and may causally contribute to its development. The study sample consisted of 7 065 Framingham Heart Study participants with measurements of plasma β₂M. Generalized estimating equations were used to test the association of β₂M with prevalent and new-onset hypertension. There were 2 145 (30%) cases of prevalent hypertension at baseline and 886 (21%) cases of incident hypertension during 6 years of follow-up. A 1-SD increase in baseline plasma β₂M was associated with a greater risk of prevalent (odds ratio 1.14, 95% CI 1.05-1.24) and new-onset (odds ratio 1.18, 95% CI 1.07-1.32) hypertension. Individuals within the top β₂M quartile had a greater risk than the bottom quartile for prevalent (odds ratio 1.29, 95% CI 1.05-1.57) and new-onset (odds ratio 1.59, 95% CI 1.20-2.11) hypertension. These associations remained essentially unchanged in analyses restricted to participants free of albuminuria and chronic kidney disease. Mendelian randomization demonstrated that lower SH2B3 expression is causal for increased circulating β₂M levels, and in a hypertensive mouse model, knockout of Sh2b3 increased β ₂ M gene expression. In a community-based study of healthy individuals, higher plasma β₂M levels are associated with increased risk of prevalent and incident hypertension independent of chronic kidney disease status. Overlapping genetic signals for hypertension and β₂M, in conjunction with mouse knockout experiments, suggest that the SH2B3-β₂M axis plays a causal role in hypertension.

Effect of SGLT2 inhibitor on renal function in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study summarizes the evidence from randomized controlled trials (RCTs) to assess the effects of SGLT2 inhibitors on renal function and albuminuria in patients with type 2 diabetes.

MATERIALS/METHODS

We searched PubMed, Web of Science, Cochrane Library and EMBASE for reports published up to March 2018 and included RCTs reporting estimated glomerular filtration rate (eGFR) and/or urine albumin/creatinine ratio (UACR) changes. Data extraction and assessment of research quality based on Cochrane risk biasing tools. Data were calculated to represent the standardized mean difference (SMD) for each study, and the SMDs with 95% confidence intervals (CIs) were pooled using a random effects model.

RESULTS

Fifty-one studies were included that evaluated eGFR levels, and 17 studies were included that evaluated UACR levels. A meta-analysis showed that SGLT2 inhibitors had no significant effect on eGFR levels (SMD - 0.02, 95% CI - 0.06, 0.03, p = 0.45), and eGFR reduction was observed in the subsets of the duration of the trial 12 < duration ≤ 26 weeks (SMD - 0.08, 95% CI - 0.13, - 0.02, p = 0.005) and mean baseline eGFR < 60 ml/min per 1.73 square meters (SMD - 0.22, 95% CI - 0.37, - 0.07, p = 0.004). We found that SGLT2 inhibitors reduced UACR levels in patients with type 2 diabetes (SMD - 0.11, 95% CI - 0.17, - 0.05, p = 0.0001). Compared with monotherapy, the combination with other hypoglycemic agents can reduce albuminuria levels (SMD - 0.13, 95% CI - 0.19, - 0.06, p < 0.0001).

CONCLUSIONS

The effect of SGLT2 inhibitor on eGFR in patients with T2DM was not statistically significant, but it was effective in reducing albuminuria levels.

Genome-wide mapping of plasma protein QTLs identifies putatively causal genes and pathways for cardiovascular disease

Identifying genetic variants associated with circulating protein concentrations (protein quantitative trait loci; pQTLs) and integrating them with variants from genome-wide association studies (GWAS) may illuminate the proteome's causal role in disease and bridge a knowledge gap regarding SNP-disease associations. We provide the results of GWAS of 71 high-value cardiovascular disease proteins in 6861 Framingham Heart Study participants and independent external replication. We report the mapping of over 16,000 pQTL variants and their functional relevance. We provide an integrated plasma protein-QTL database. Thirteen proteins harbor pQTL variants that match coronary disease-risk variants from GWAS or test causal for coronary disease by Mendelian randomization. Eight of these proteins predict new-onset cardiovascular disease events in Framingham participants. We demonstrate that identifying pQTLs, integrating them with GWAS results, employing Mendelian randomization, and prospectively testing protein-trait associations holds potential for elucidating causal genes, proteins, and pathways for cardiovascular disease and may identify targets for its prevention and treatment.

Albuminuria and kidney function as prognostic marker of left ventricular mass among South Asians with hypertension

We aimed to evaluate the association of albuminuria and estimated glomerular filtration rate (eGFR) at baseline and changes in these parameters with left ventricular mass index (LVMI) at 7 years in adults with hypertension from communities in Pakistan. A nested cohort of 539 hypertensives aged 40 years and older from a community-living population in Karachi, Pakistan, followed up for 7 years in the Control of Blood Pressure and Risk Attenuation trial. Urine spot albumin-to-creatinine ratio (UACR) and serum creatinine-based eGFR were assessed at baseline and 7 years, and echocardiography at 7 years. Mean age of participants was 50.9 ± 9.1 (standard deviation) years; 63% were female. Mean eGFR was 91.0 ± 15.9 (standard deviation) mL/min/1.73 m² and median (interquartile range) UACR 6.2 (3.9, 11.3) mg/g. In multivariate analysis, although baseline eGFR was marginally associated with LVMI, a strong association was found between higher LVMI with greater rate of decline in eGFR (β = -1.05; 95% confidence interval [CI]: [-1.94, -0.17]). Higher baseline UACR was significantly associated with higher follow-up LVMI (β = 2.26; 95% CI: [0.87, 3.65]), as was rate of UACR increase of ≥1.07 mg/g/y versus of <0.14 mg/g/y. (β = 4.19; 95% CI: [0.75, 7.63]). Associations with developing left ventricular hypertrophy were found for reduced baseline eGFR, higher baseline UACR, and greater rate of UACR increase, but not for rate of eGFR decline. Comparable results were observed for the outcomes of posterior wall thickness and septal wall thickness. Higher baseline albuminuria, lower baseline eGFR, and their longitudinal worsening were significantly associated with higher LVMI or the development of left ventricular hypertrophy among individuals with hypertension in Pakistan.

APOL1 genetic variants are not associated with longitudinal blood pressure in young black adults

Whether APOL1 polymorphisms contribute to the excess risk of hypertension among blacks is unknown. To assess this we evaluated whether self-reported race and, in blacks, APOL1 risk variants (high-risk [2 risk alleles] versus low-risk [0-1 risk allele]) were associated with longitudinal blood pressure. Blood pressure trajectories were determined using linear mixed-effects (slope) and latent class models (5 distinct groups) during 25 years of follow-up in the Coronary Artery Risk Development in Young Adults Study. Associations of race and APOL1 genotypes with blood pressure change, separately, using linear mixed-effects and multinomial logistic regression models, adjusting for demographic, socioeconomic, and traditional hypertension risk factors, anti-hypertensive medication use, and kidney function were evaluated. Among 1700 whites and 1330 blacks (13% APOL1 high-risk, mean age 25 years; 46% male) mean mid-, ([systolic + diastolic blood pressure]/2), systolic, and diastolic blood pressures were 89, 110, and 69 mm Hg, respectively. One percent of participants used anti-hypertensive medications at baseline. Compared to whites, blacks, regardless of APOL1 genotype, had significantly greater increases in mid-blood pressure and were more likely to experience significantly increasing mid-blood pressure trajectories with adjusted relative risk ratios of 5.21 and 7.27 for moderate-increasing and elevated-increasing versus low-stable blood pressure, respectively. Among blacks, longitudinal mid-blood pressure changes and mid-blood pressure trajectory classification were similar by APOL1 risk status. Modeling systolic and diastolic blood pressure as outcomes yielded similar findings. From young adulthood to mid-life, blacks have greater blood pressure increases versus whites that are not fully explained by traditional risk factors. Thus APOL1 variants are not associated with longitudinal blood pressure in blacks.

Prevalence and determinants of chronic kidney disease in northeast of Iran: Results of the Golestan cohort study

Background

The burden of chronic kidney disease (CKD) is increasing globally in particular in fast emerging economies such as Iran. Population-based studies on prevalence of CKD in Iran are scarce. The objective of the current study was to explore the prevalence and determinants of CKD in the setting of Golestan Cohort Study (GCS), the largest prospective cohort in the Middle East.

Methods

In this observational study, 11,409 participants enrolled in the second phase of GCS were included. Sex, age, literacy, residence, anthropometric measurements, smoking, opium use, self-reported history of cardiovascular diseases (heart disease and/or stroke), hypertension, diabetes, and lipid profile were the predictors of interest. The outcomes of interest were eGFR and CKD defined as eGFR< 60 ml/min/1.73m².

Results

Mean (SD) of GFR was 70.0 ± 14.7 ml/min/1.73m² among all participants, 68.2 ± 14.2 among women, and 72.0 ± 15.0 among men. Prevalence of CKD was 23.7% (26.6% in women, 20.6% in men). The prevalence of CKD stages 3a, 3b, 4, and 5 were 20.0%, 3.3%, 0.4% and 0.1%, respectively. Female sex, older age, urban residence, history of CVD, hypertension or diabetes, larger body mass and surrogates of body fat and opium use were all associated with CKD. Opium had a significant positive association with CKD in adjusted model. All anthropometric measurements had positive linear association with CKD. Being literate had inverse association. Sex had significant interaction with anthropometric indices, with higher odds ratios among men compared with women. A significantly high association was observed between the rate of change in waist circumference and systolic blood pressure with risk of CKD.

Conclusion

One in four people in this cohort had low eGFR. Obesity and overweight, diabetes, hypertension, and dyslipidemia are major risk factors for CKD. Halting the increase in waist circumference and blood pressure may be as important as reducing the current levels.

Beta-trace Protein as a new non-invasive immunological Marker for Quinolinic Acid-induced impaired Blood-Brain Barrier Integrity

Quinolinic acid, a macrophage/microglia-derived excitotoxin fulfills a plethora of functions such as neurotoxin, gliotoxin, and proinflammatory mediator, and it alters the integrity and cohesion of the blood-brain barrier in several pathophysiological states. Beta-trace protein (BTP), a monomeric glycoprotein, is known to indicate cerebrospinal fluid leakage. Thus, the prior aim of this study was to investigate whether BTP might non-invasively indicate quinolinic acid-induced impaired blood-brain barrier integrity. The research hypotheses were tested in three subsamples with different states of immune activation (patients with HCV-infection and interferon-α, patients with major depression, and healthy controls). BTP has also been described as a sensitive marker in detecting impaired renal function. Thus, the renal function has been considered. Our study results revealed highest quinolinic acid and highest BTP- levels in the subsample of patients with HCV in comparison with the other subsamples with lower or no immune activation (quinolinic acid: F = 21.027, p < 0.001 [ANOVA]; BTP: F = 6.792, p < 0.01 [ANOVA]). In addition, a two-step hierarchical linear regression model showed that significant predictors of BTP levels are quinolinic acid, glomerular filtration rate and age. The neurotoxin quinolinic acid may impair blood-brain barrier integrity. BTP might be a new non-invasive biomarker to indicate quinolinic acid-induced impaired blood-brain barrier integrity.

Association Between Serum β2 -Microglobulin Levels and Prevalent and Incident Physical Frailty in Community-Dwelling Older Women

OBJECTIVES

To investigate whether higher serum β₂ -microglobulin (B2M) levels, a kidney function marker, are associated with prevalent and incident frailty in community-dwelling older women.

DESIGN

Cross-sectional and longitudinal analyses of a prospective cohort.

SETTING

Population-based cohort study in Tokyo, Japan.

PARTICIPANTS

Community-dwelling women aged 75 and older with adequate data for assessing frailty status (N = 1,191) and a subset of participants without baseline frailty but with repeated frailty assessment at 2 and 4 years of follow-up.

MEASUREMENTS

The primary predictor was B2M level. Outcomes were prevalent and incident frailty during the 4-year follow-up period. Frailty was defined as presence of three of the five Fried criteria: weight loss, exhaustion, weakness, slowness, and low physical activity. Adjusted odds ratios for the main confounders were obtained using logistic regression. Discrete-time Cox proportional hazards models were used to determine the risk of developing frailty.

RESULTS

The study included 241 (20.2%) women with prevalent frailty at baseline and 139 (21.1%) with incident frailty during the 4-year follow-up. On multivariate analysis adjusted for multiple potential confounders, the odds of prevalent frailty were 2.5 times as great with B2M levels of 1.9 to 2.1 mg/L as with levels less than 1.6 mg/L and 2.0 times as great with B2M levels of 2.2 mg/L or more. In the unadjusted model, B2M levels of 1.9 to 2.1 mg/L were associated with a greater incidence of frailty than B2M levels of less than 1.6 mg/L (hazard ratio = 1.72, 95% confidence interval = 1.04-2.86). In the multivariate analysis adjusted for potential confounders, no significant association was noted between the highest B2M quartile and incident frailty.

CONCLUSION

Higher B2M levels were independently associated with greater frailty at baseline in older adults but only slightly associated with greater risk of incident frailty over 4 years of follow-up.

Association of Kidney Function and Early Kidney Injury With Incident Hypertension in HIV-Infected Women

Subclinical kidney disease is associated with developing hypertension in the general population, but data are lacking among HIV-infected people. We examined associations of kidney function and injury with incident hypertension in 823 HIV-infected and 267 HIV-uninfected women in the Women's Interagency HIV Study, a multicenter, prospective cohort of HIV-infected and uninfected women in the United States. Baseline kidney biomarkers included estimated glomerular filtration rate using cystatin C, urine albumin-to-creatinine ratio, and 7 urine biomarkers of tubular injury: α-1-microglobulin, interleukin-18, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, liver fatty acid-binding protein, N-acetyl-β-d-glucosaminidase, and α1-acid-glycoprotein. We used multivariable Poisson regression to evaluate associations of kidney biomarkers with incident hypertension, defined as 2 consecutive visits of antihypertensive medication use. During a median follow-up of 9.6 years, 288 HIV-infected women (35%) developed hypertension. Among the HIV-infected women, higher urine albumin-to-creatinine ratio was independently associated with incident hypertension (relative risk =1.13 per urine albumin-to-creatinine ratio doubling, 95% confidence interval, 1.07-1.20), as was lower estimated glomerular filtration rate (relative risk =1.10 per 10 mL/min/1.73 m² lower estimated glomerular filtration rate; 95% confidence interval, 1.04-1.17). No tubular injury and dysfunction biomarkers were independently associated with incident hypertension in HIV-infected women. In contrast, among the HIV-uninfected women, urine albumin-to-creatinine ratio was not associated with incident hypertension, whereas higher urine interleukin-18, α1-acid-glycoprotein, and N-acetyl-β-d-glucosaminidase levels were significantly associated with incident hypertension. These findings suggest that early glomerular injury and kidney dysfunction may be involved in the pathogenesis of hypertension in HIV-infected people. The associations of tubular markers with hypertension in HIV-uninfected women should be validated in other studies.

Associations between cystatin C-based eGFR, ambulatory blood pressure parameters, and in-clinic versus ambulatory blood pressure agreement in older community-living adults

OBJECTIVES

The objective of this study was to determine the relationship between chronic kidney disease [CKD; measured using cystatin C-based estimated glomerular filtration rate (eGFR)] and abnormal ambulatory blood pressure (including nocturnal dipping) in healthy older adults. Further, this study aimed to assess the agreement between clinic and ambulatory blood pressure monitoring.

METHODS

Serum cystatin C levels were measured to calculate eGFR. Participants underwent clinic and 24-h ambulatory blood pressure measurements. Multiple linear regression was performed to examine the association between reduced cystatin C-based eGFR (CKDcys) and blood pressure parameters. Bland-Altman analysis was carried out to evaluate the agreement between clinic and ambulatory measurements.

RESULTS

The average age was 72 years. There were 60 individuals with CKDcys (eGFR<60 ml/min/1.73 m). Compared with those without CKDcys, individuals with CKDcys were older, more likely to have hypertension, and less likely to have normal dipping patterns. On multivariate analysis, the presence of CKDcys was found to be significantly associated with a lower mean ambulatory diastolic blood pressure (-2 mmHg, P=0.048), but not with nocturnal dipping or other blood pressure parameters. Clinic systolic blood pressure (SBP) significantly overestimated the mean wake-time ambulatory SBP; the mean difference was 11 mmHg for those without CKDcys (95% limits of agreement -14 to 35 mmHg) and 14 mmHg for those with CKDcys (95% limits of agreement -13 to 41 mmHg); there was no statistically significant effect modification by CKD status.

CONCLUSION

In older, seemingly healthy adults, mild CKD was associated with lower ambulatory diastolic blood pressure. The presence of CKD did not affect interpretation of clinic versus ambulatory blood pressure monitoring, although the accuracy of clinic SBP was poor.

Serum Beta-Trace Protein as a Novel Predictor of Pregnancy-Induced Hypertension

Beta-trace protein (BTP) has emerged as a novel biomarker of cardiovascular risk. However, the level of circulating BTP in pregnancy-induced hypertension (PIH) is still unknown. The aim of this study was to determine the concentration of serum BTP in healthy pregnant women and patients with PIH. No significant difference was found in the serum concentration of BTP in patients with a normal pregnancy. In contrast, serum BTP levels in women with PIH (n=46) were significantly higher than those in women with normal pregnancy (n=57). Receiver operating characteristic analysis revealed that using a serum BTP value of 321.3 ng/mL as a cutoff produced a sensitivity of 91.3% and a specificity of 89.5%. Taken together, these findings suggest that a higher serum BTP concentration in PIH patients compared with those with normal pregnancy and serum BTP might be a novel biomarker in the diagnosis of PIH.

Race, APOL1 Risk, and eGFR Decline in the General Population

The APOL1 high-risk genotype, present in approximately 13% of blacks in the United States, is a risk factor for kidney function decline in populations with CKD. It is unknown whether genetic screening is indicated in the general population. We evaluated the prognosis of APOL1 high-risk status in participants in the population-based Atherosclerosis Risk in Communities (ARIC) study, including associations with eGFR decline, variability in eGFR decline, and related adverse health events (AKI, ESRD, hypertension, diabetes, cardiovascular disease, pre-ESRD and total hospitalization rate, and mortality). Among 15,140 ARIC participants followed from 1987-1989 (baseline) to 2011-2013, 75.3% were white, 21.5% were black/APOL1 low-risk, and 3.2% were black/APOL1 high-risk. In a demographic-adjusted analysis, blacks had a higher risk for all assessed adverse health events; however, in analyses adjusted for comorbid conditions and socioeconomic status, blacks had a higher risk for hypertension, diabetes, and ESRD only. Among blacks, the APOL1 high-risk genotype associated only with higher risk of ESRD in a fully adjusted analysis. Black race and APOL1 high-risk status were associated with faster eGFR decline (P<0.001 for each). However, we detected substantial overlap among the groups: median (10th-90th percentile) unadjusted eGFR decline was 1.5 (1.0-2.2) ml/min per 1.73 m(2) per year for whites, 2.1 (1.4-3.1) ml/min per 1.73 m(2) per year for blacks with APOL1 low-risk status, and 2.3 (1.5-3.5) ml/min per 1.73 m(2) per year for blacks with APOL1 high-risk status. The high variability in eGFR decline among blacks with and without the APOL1 high-risk genotype suggests that population-based screening is not yet justified.

Multiple biomarkers for mortality prediction in peripheral arterial disease

Few studies have assessed which biomarkers influence mortality risk among those with peripheral arterial disease (PAD). We analyzed data from 556 individuals identified to have PAD (i.e. ankle–brachial index ⩽0.9) with available measurements of C-reactive protein, the neutrophil-to-lymphocyte ratio (NLR), homocysteine, and the urinary albumin-to-creatinine ratio (UACR) in the 1999–2004 National Health and Nutrition Examination Survey. We investigated whether a combination of these biomarkers improved the prediction of all-cause and cardiovascular mortality beyond conventional risk factors. During follow-up (median, 8.1 years), 277 of 556 participants died; 63 deaths were attributed to cardiovascular disease. After adjusting for conventional risk factors, Cox proportional-hazards models showed the following to be most strongly associated with all-cause mortality (each is followed by the adjusted hazard ratio [HR] per 1 standard deviation increment in the log values): homocysteine (1.31), UACR (1.21), and NLR (1.20). UACR alone significantly predicted cardiovascular mortality (1.53). Persons in the highest quintile of multimarker scores derived from regression coefficients of significant biomarkers had elevated risks of all-cause mortality (adjusted HR, 2.45; 95% CI, 1.66–3.62; p for trend, <0.001) and cardiovascular mortality (adjusted HR, 2.20; 95% CI, 1.02–4.71; p for trend, 0.053) compared to those in the lowest two quintiles. The addition of continuous multimarker scores to conventional risk factors improved risk stratification of all-cause mortality (integrated discrimination improvement [IDI], 0.162; p<0.00001) and cardiovascular mortality (IDI, 0.058; p<0.00001). In conclusion, the addition of a continuous multimarker score to conventional risk factors improved mortality prediction among patients with PAD.

Documentation of renal glomerular and tubular impairment and glomerular hyperfiltration in multitransfused patients with beta thalassemia

Urinary albumin to creatinine (ACR) and beta2 microglobulin to creatinine ratios (BCR) are the surrogate and robust markers of renal glomerulopathy and tubulopathy, respectively. These markers predict short-term renal deterioration and mortality in various conditions. We aimed to assess the frequency and predictors of glomerular and tubular defects, renal impairment, and hyperfiltration in 96 adult patients with beta thalassemia intermedia and major. ACR > 300 mg/g creatinine and BCR > 300 μg/g creatinine were used to define the renal glomerular and tubular damages, respectively. Glomerular filtration rate (eGFRcreat) was estimated according to 2009 the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Decreased eGFRcreat was defined as less than 60 mL/min per 1.73 m(2). Renal glomerular and/or tubular defects were observed in about 68.8 % of all patients. Forty percent of patients had glomerular hyperfiltration. None of the patients had a decreased eGFRcreat. T2* value ≤20 msec on cardiac magnetic resonance (cMR) was the only independent predictor of glomerular damage (p = 0.013). Use of alendronate was associated with less renal tubular damage (p = 0.007). Female gender and previous history of splenectomy were the independent predictors of glomerular hyperfiltration in multivariate analysis (p < 0.001 and p = 0.040, respectively). Renal tubular and glomerular damage is frequent in adult patients with thalassemia intermedia and major. T2* value on cMR was the only independent predictor of glomerular damage. However, since we did not explore all the parameters of iron, it is not possible to draw a definite conclusion about the association of cMR and glomerular damage. There is no association with cardiac iron overload/accumulation and tubular damage or hyperfiltration.

Influence of chronic kidney disease on cardiac structure and function

Chronic kidney disease (CKD), the presence of kidney dysfunction and/or damage, is a worldwide public health issue. Although CKD is independently associated with various subtypes of cardiovascular diseases, a recent international collaborative meta-analysis demonstrates that CKD is particularly strongly associated with heart failure, suggesting its critical impact on cardiac structure and function. Although numerous studies have investigated the association of CKD and cardiac structure and function, these studies substantially vary regarding source populations and methodology (e.g., measures of CKD and/or parameters of cardiac structure and function), making it difficult to reach universal conclusions. Nevertheless, in this review, we comprehensively examine relevant studies, discuss potential mechanisms linking CKD to alteration of cardiac structure and function, and demonstrate clinical implications as well as potential future research directions. We exclusively focus on studies investigating both CKD measures, kidney function (i.e., glomerular filtration rate [GFR], creatinine clearance, or levels of filtration markers), and kidney damage represented by albuminuria, since current international clinical guidelines of CKD recommend staging CKD and assessing its clinical risk based on both GFR and albuminuria.

Elevated Serum Beta-Trace Protein Levels are Associated With the Presence of Atrial Fibrillation in Hypertension Patients

Beta-trace protein (BTP) has emerged as a novel biomarker of cardiovascular risk. In this study, the authors aimed to assess the relationship between BTP levels and presence of atrial fibrillation in patients who had controlled hypertension (HTN) and normal renal function. A total of 80 controlled HTN patients with paroxysmal atrial fibrillation (PAF) and 80 age- and sex-matched controls with controlled HTN were enrolled. Serum BTP levels were measured by enzyme-linked immunosorbent assay. BTP levels were found to be significantly higher in patients with PAF (P<.001). Other parameters including mean systolic and diastolic blood pressure values, serum creatinine levels, and glomerular filtration rate were similar between the two groups. Along with left atrial diameter (odds ratio, 1.504; P<.001), BTP levels (odds ratio, 1.015; P<.001) were independently associated with the presence of PAF. BTP levels were increased in controlled HTN patients with PAF compared with controls, and this association was observed within normal renal functions as reflected by normal glomerular filtration rate.

Albuminuria, renal dysfunction and circadian blood pressure rhythm in older men: a population-based longitudinal cohort study

Background

Both albuminuria and kidney dysfunction may affect circadian blood pressure (BP) rhythm, while exacerbating each other's effects. We investigated associations and interactions of these two risk factors with circadian BP rhythm variation and non-dipper pattern progression in community-dwelling older men.

Methods

This was a cross-sectional and longitudinal analyses in the third and fourth cycles of the Uppsala Longitudinal Study of Adult Men, including 1051 men (age 71 years) with assessments on urinary albumin excretion rate (UAER), 24-h ambulatory BP monitoring (ABPM) and cystatin-C-estimated glomerular filtration rate (eGFR). Of these, 574 men attended re-examination after 6 years. Study outcomes were ABMP changes and non-dipping BP pattern (prevalence and progression).

Results

UAER associated with circadian BP rhythm both cross-sectionally and longitudinally. Longitudinally, significant interactions were observed between UAER and kidney dysfunction (eGFR < 60 mL/min/1.73 m²) in its association with the changes of both night-time systolic BP (SBP) and night–day SBP ratio. After stratification, UAER strongly predicted night–day SBP ratio change only in those with concurrent kidney dysfunction. At re-examination, 221 new cases of non-dipper were identified. In multivariable logistic models, high UAER associated with increased likelihood of non-dipper progression, but more strongly so among individuals with concurrent kidney dysfunction. These associations were evident also in the subpopulation of non-diabetics and in participants with normal range UAER.

Conclusions

UAER associates with circadian BP rhythm variation and non-dipper progression in elderly men. Concurrent renal dysfunction modifies and exacerbates these associations.

Assessment of Serum Cystatin C Levels in Newly Diagnosed Acute Myocardial Infarction at the Onset and at the Time of Hospital Discharge

BACKGROUND

Cystatin C (Cys-C) is a marker of renal damage. Higher serum levels of Cys-C were observed in cardiovascular disease. This study aimed to test the null hypothesis that Cys-C levels in newly diagnosed acute myocardial infarction (AMI) may remain high in the survival and the impact of the cardiometabolic risk factors is small.

METHODS

Forty patients with AMI are enrolled in this study. The cardiometabolic factors including the anthropometric measurements, blood pressure and lipid profile were determined. The diagnosis of AMI is based on the electrocardiograph, cardiac enzymes and positive troponin-c (cTn) test. Quantitative determination of serum high sensitive C-reactive protein (hs-CRP) and Cys-C was carried out, at the time of admission and at the time of the discharge, using the enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

Serum Cys-C levels significantly increased at the time of the admission (1,296 ± 431.8 ng/mL) and at the time of the discharge (1,244.6 ± 482 ng/mL) compared with the reference levels (0.7 ± 0.2 ng/mL) of the healthy subjects. Non-significant differences were found between Cys-C levels in respect to the presence or absence of the cardiometabolic risk factors at the times of admission and discharge. Significant decrease of Cys-C levels was found in patients who have negative cTn at the time of discharge compared with corresponding levels at the time of admission.

CONCLUSIONS

We conclude that AMI patients have significant high serum levels of Cys-C at the time of admission and the levels significantly decreased in patients with negative cTn test within few days indicating an association between infarct size and the levels of Cys-C.