Blood pressure, atherosclerosis, and albuminuria in 10,113 participants in the atherosclerosis risk in communities study

Prevalence and Associated Factors of Atherosclerotic Plaque and Stenosis in Renal Arteries: A Community-Based Study

The epidemiology of renal artery atherosclerosis in community populations is poorly documented. This study aimed to determine the prevalence of renal artery plaque (RAP) and atherosclerotic renal artery stenosis (ARAS), and the association of plaque and stenosis with vascular risk factors and kidney disease markers among community-dwelling adults. We conducted a cross-sectional analysis of the Polyvascular Evaluation for Cognitive Impairment and Vascular Events (PRECISE) study. RAP and ARAS were evaluated by thoracoabdominal computed tomography angiography. A total of 3045 adults aged 50-75 years were included. The prevalence of RAP and ARAS was 28.7% and 4.8%, respectively. The prevalence of RAP and ARAS was 41.3% and 7.7% in individuals aged ≥60 years, 42.9% and 8.7% in hypertensives, and 45.4% and 8.5% in individuals with chronic kidney disease. Older age, hypertension, higher total cholesterol level, and lower high-density lipoprotein cholesterol level were independently associated with RAP and ARAS. A higher urinary albumin-creatinine ratio was independently associated with RAP, whereas a reduced estimated glomerular filtration rate was independently associated with ARAS. In conclusion, there was a non-negligible prevalence of RAP and ARAS among the older, community population in China.

Sex differences in impact of cumulative systolic blood pressure from childhood to adulthood on albuminuria in midlife: a 30-year prospective cohort study

BACKGROUND AND OBJECTIVES

Albuminuria is recognized as being a predictor of cardiovascular and renal disease. We aimed to identify the impact of the long-term burden and trends of systolic blood pressure on albuminuria in midlife, as well as to explore sex differences concerning this relationship.

METHODS

This longitudinal study consisted of 1,683 adults who had been examined 4 or more times for blood pressure starting in childhood, with a follow-up time period of 30 years. The cumulative effect and longitudinal trend of blood pressure were identified by using the area under the curve (AUC) of individual systolic blood pressure measurement with a growth curve random effects model.

RESULTS

Over 30 years of follow-up, 190 people developed albuminuria, including 53.2% males and 46.8% females (aged 43.39 ± 3.13 years in the latest follow-up). The urine albumin-to-creatinine ratio (uACR) values increased as the total and incremental AUC values increased. Additionally, women had a higher albuminuria incidence in the higher SBP AUC groups than men do (13.3% for men vs. 33.7% for women). Logistic regression showed that the ORs of albuminuria for males and females in the high total AUC group were 1.34 (0.70-2.60) and 2.94 (1.50-5.74), respectively. Similar associations were found in the incremental AUC groups.

CONCLUSIONS

Higher cumulative SBP was correlated with higher uACR levels and a risk of albuminuria in middle age, especially in women. The identification and control of cumulative SBP levels from an early age may assist in reducing the incidences of renal and cardiovascular disease for individuals in later life.

Comparing Multiple Linear Regression and Machine Learning in Predicting Diabetic Urine Albumin–Creatinine Ratio in a 4-Year Follow-Up Study

The urine albumin–creatinine ratio (uACR) is a warning for the deterioration of renal function in type 2 diabetes (T2D). The early detection of ACR has become an important issue. Multiple linear regression (MLR) has traditionally been used to explore the relationships between risk factors and endpoints. Recently, machine learning (ML) methods have been widely applied in medicine. In the present study, four ML methods were used to predict the uACR in a T2D cohort. We hypothesized that (1) ML outperforms traditional MLR and (2) different ranks of the importance of the risk factors will be obtained. A total of 1147 patients with T2D were followed up for four years. MLR, classification and regression tree, random forest, stochastic gradient boosting, and eXtreme gradient boosting methods were used. Our findings show that the prediction errors of the ML methods are smaller than those of MLR, which indicates that ML is more accurate. The first six most important factors were baseline creatinine level, systolic and diastolic blood pressure, glycated hemoglobin, and fasting plasma glucose. In conclusion, ML might be more accurate in predicting uACR in a T2D cohort than the traditional MLR, and the baseline creatinine level is the most important predictor, which is followed by systolic and diastolic blood pressure, glycated hemoglobin, and fasting plasma glucose in Chinese patients with T2D.

Association of the Atherogenic Index of Plasma with C-Reactive Protein and Urinary Albumin Excretion in a Normotensive Nondiabetic Population

Background: The atherogenic index of plasma (AIP) is an indicator of atherogenic dyslipidemia and is significantly associated with the development of atherosclerotic cardiovascular disease. Previous studies showing the association of AIP with C-reactive protein (CRP) and microalbuminuria included hypertensive and diabetic patients. We aimed to determine the association of AIP with CRP and albuminuria in a normotensive and nondiabetic population. Methods: The study was conducted retrospectively. Two hundred thirty-three individuals without hypertension, diabetes, cardiovascular disease, malignancy, systemic inflammatory disease, nephrological disease, and active infection were determined and included in the study. Urinary albumin excretion was calculated from the albumin-creatinine ratio in fresh spot urine [urinary albumin-creatinine ratio (UACR)]. AIP risk groups were compared in terms of clinical and laboratory findings, and the correlation between AIP and CRP and UACR was evaluated. Results: A total of 233 people, with a mean age of 45.4 years and 139 (69.7%) of whom were male, were included in the study. One hundred thirty-eight (59.2%) individuals were found to be in the low-risk group, 29 (12.5%) in the medium-risk group, and 66 (28.3%) in the high-risk group, according to the AIP value. CRP and UACR were not different between the AIP risk groups (P: 0.141 and 0.441, respectively). A mild correlation was found between AIP and CRP (r: 0.192; P: 0.003), but no correlation was found between AIP and UACR (r: 0.086; P: 0.193). The stepwise linear regression analysis with model adjusted for possible confounders and AIP revealed that only body mass index was a significant predictor of CRP (β: 0.308; P < 0.001), while only systolic blood pressure was a significant predictor of UACR (β: 0.19; P: 0.004), but AIP was not. Conclusions: AIP was not associated with CRP and UACR in normotensive and nondiabetic individuals. This finding suggests that the relationship found in previous studies is related to the presence of hypertension or diabetes rather than the AIP.

Prevalence of Albuminuria in Cardiology and Endocrinology Departments and Its Influencing Factors: A Multicenter, Real-World Evidence Study in China

AIMS

To evaluate the prevalence of albuminuria and compare its risk factors in diabetic and hypertensive patients.

METHODS

This was an observational, cross-sectional, multicenter registry across China. Consecutive patients were registered with the Cardiology and Endocrine departments in 40 centers. Clinical characteristics were collected, and urinary albumin-to-creatinine ratio (UACR) was measured using the immunochemical method.

RESULTS

Of the 2510 patients enrolled in the study, 1515 underwent UACR testing and were included in the present analysis. The prevalence of microalbuminuria was 13.0% and 16.1% while that of macroalbuminuria was 2.5% and 5.0%, in the Cardiology and Endocrinology departments, respectively. HbA1c and systolic blood pressure (SBP) were independent risk factors for albuminuria. The relationship of blood pressure (BP) and HbA1c with albuminuria was continuous and graded. Compared with the reference level of SBP 130-139 mm Hg, an SBP level of <130 mmHg was significantly associated with a lower risk of albuminuria in all subjects (OR = 0.60; 95% CI: 0.40-0.89; P < 0.001) and in subjects with concomitant hypertension and diabetes (OR = 0.48; 95% CI: 0.25-0.92; P < 0.001).

CONCLUSIONS

In China, nearly one-fifth of patients in the Cardiology and Endocrinology departments have albuminuria although ACEI/ARB were widely used. More effective therapy is needed in this population.

Natriuretic Peptide and High-Sensitivity Troponin for Cardiovascular Risk Prediction in Diabetes: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in diabetes; yet, heterogeneity in CVD risk has been suggested in diabetes, providing a compelling rationale for improving diabetes risk stratification. We hypothesized that N-terminal prohormone brain natriuretic peptide (NTproBNP) and high-sensitivity troponin T may enhance CVD risk stratification beyond commonly used markers of risk and that CVD risk is heterogeneous in diabetes.

RESEARCH DESIGN AND METHODS

Among 8,402 participants without prevalent CVD at visit 4 (1996-1998) of the Atherosclerosis Risk in Communities (ARIC) study there were 1,510 subjects with diabetes (mean age 63 years, 52% women, 31% African American, and 60% hypertensive).

RESULTS

Over a median follow-up of 13.1 years, there were 540 incident fatal/nonfatal CVD events (coronary heart disease, heart failure, and stroke). Both troponin T ≥14 ng/L (hazard ratio [HR] 1.96 [95% CI 1.57-2.46]) and NTproBNP >125 pg/mL (1.61 [1.29-1.99]) were independent predictors of incident CVD events at multivariable Cox proportional hazard models. Addition of circulating cardiac biomarkers to traditional risk factors, abnormal electrocardiogram (ECG), and conventional markers of diabetes complications including retinopathy, nephropathy, and peripheral arterial disease significantly improved CVD risk prediction (net reclassification index 0.16 [95% CI 0.07-0.22]). Compared with individuals without diabetes, subjects with diabetes had 1.6-fold higher adjusted risk of incident CVD. However, participants with diabetes with normal cardiac biomarkers and no conventional complications/abnormal ECG (n = 725 [48%]) were at low risk (HR 1.12 [95% CI 0.95-1.31]), while those with abnormal cardiac biomarkers, alone (n = 186 [12%]) or in combination with conventional complications/abnormal ECG (n = 243 [16%]), were at greater risk (1.99 [1.59-2.50] and 2.80 [2.34-3.35], respectively).

CONCLUSIONS

Abnormal levels of NTproBNP and troponin T may help to distinguish individuals with high diabetes risk from those with low diabetes risk, providing incremental risk prediction beyond commonly used markers of risk.

Subclinical Kidney Damage in Hypertensive Patients: A Renal Window Opened on the Cardiovascular System. Focus on Microalbuminuria

The kidney is one of the major target organs of hypertension.Kidney damage represents a frequent event in the course of hypertension and arterial hypertension is one of the leading causes of end-stage renal disease (ESRD).ESRD has long been recognized as a strong predictor of cardiovascular (CV) morbidity and mortality. However, over the past 20 years a large and consistent body of evidence has been produced suggesting that CV risk progressively increases as the estimated glomerular filtration rate (eGFR) declines and is already significantly elevated even in the earliest stages of renal damage. Data was supported by the very large collaborative meta-analysis of the Chronic Kidney Disease Prognosis Consortium, which provided undisputable evidence that there is an inverse association between eGFR and CV risk. It is important to remember that in evaluating CV disease using renal parameters, GFR should be assessed simultaneously with albuminuria.Indeed, data from the same meta-analysis indicate that also increased urinary albumin levels or proteinuria carry an increased risk of all-cause and CV mortality. Thus, lower eGFR and higher urinary albumin values are not only predictors of progressive kidney failure, but also of all-cause and CV mortality, independent of each other and of traditional CV risk factors.Although subjects with ESRD are at the highest risk of CV diseases, there will likely be more events in subjects with mil-to-moderate renal dysfunction, because of its much higher prevalence.These findings are even more noteworthy when one considers that a mild reduction in renal function is very common in hypertensive patients.The current European Society of Hypertension (ESH)/European Society of Cardiology (ESC) guidelines for the management of arterial hypertension recommend to sought in every patient signs of subclinical (or asymptomatic) renal damage. This was defined by the detection of eGFR between 30 mL/min/1.73 m² and 60 mL/min/1.73 m² or the presence of microalbuminuria (MAU), that is an amount of albumin in the urine of 30-300 mg/day or an albumin/creatinine ratio, preferentially on morning spot urine, of 30-300 mg/g.There is clear evidence that urinary albumin excretion levels, even below the cut-off values used to define MAU, are associated with an increased risk of CV events. The relationships of MAU with a variety of risk factors, such as blood pressure, diabetes and metabolic syndrome and with several indices of subclinical organ damage, may contribute, at least in part, to explain the enhanced CV risk conferred by MAU. Nonetheless, several studies showed that the association between MAU and CV disease remains when all these risk factors are taken into account in multivariate analyses. Therefore, the exact pathophysiological mechanisms explaining the association between MAU and CV risk remain to be elucidated. The simple search for MAU and in general of subclinical renal involvement in hypertensive patients may enable the clinician to better assess absolute CV risk, and its identification may induce physicians to encourage patients to make healthy lifestyle changes and perhaps would prompt to more aggressive modification of standard CV risk factors.

Creating a transdisciplinary research center to reduce cardiovascular health disparities in Baltimore, Maryland: lessons learned

Cardiovascular disease (CVD) disparities continue to have a negative impact on African Americans in the United States, largely because of uncontrolled hypertension. Despite the availability of evidence-based interventions, their use has not been translated into clinical and public health practice. The Johns Hopkins Center to Eliminate Cardiovascular Health Disparities is a new transdisciplinary research program with a stated goal to lower the impact of CVD disparities on vulnerable populations in Baltimore, Maryland. By targeting multiple levels of influence on the core problem of disparities in Baltimore, the center leverages academic, community, and national partnerships and a novel structure to support 3 research studies and to train the next generation of CVD researchers. We also share the early lessons learned in the center's design.

Elevated galectin-3 precedes the development of CKD

Galectin-3, a profibrotic mediator, is linked to the development of renal fibrosis in animal models and inversely correlates with GFR in humans, but whether galectin-3 predicts incident kidney disease is unknown. Here, we assessed renal outcomes for 2450 Framingham Offspring participants who attended examination 6 (1995-1998) and had follow-up data at examination 8 (2005-2008). Renal outcomes of interest included rapid decline in renal function (≥3 ml/min per 1.73 m(2) per year decline in estimated GFR [eGFR]), CKD (eGFR < 60 ml/min per 1.73 m(2)), and albuminuria (albumin-to-creatinine ratio ≥17 mg/g in men or ≥25 mg/g in women). We used multivariable logistic regression models to evaluate associations between galectin-3 with incident renal outcomes at examination 8. During a mean follow-up of 10.1 years, GFR declined rapidly in 241 (9.2%) participants, incident CKD developed in 277 (11.3%), and albuminuria developed in 194 (10.1%). Higher plasma levels of galectin-3 were associated with rapid decline in eGFR (per 1-SD log-galectin-3; adjusted odds ratio [OR], 1.49; 95% confidence interval [CI], 1.28 to 1.73]) and a higher risk of incident CKD (OR, 1.47; 95% CI, 1.27 to 1.71), but not with the risk of incident albuminuria. The addition of galectin-3 to clinical predictors improved the C-statistic (0.837-0.845; P=0.02) but did not reach predefined thresholds for clinically significant improvements to risk prediction based on reclassification indices. In conclusion, elevated levels of plasma galectin-3 are associated with increased risks of rapid GFR decline and of incident CKD in the community, which calls for further study in higher-risk groups.

Prevalence and covariates of abnormal left ventricular geometry in never-treated hypertensive patients in Tanzania

AIM. To assess prevalence, type and covariates of abnormal left ventricular (LV) geometry in untreated native Tanzanian patients with hypertension in relation to normotensive controls. METHODS. Echocardiography was performed in 161 untreated hypertensive outpatients and 80 normotensive controls at a tertiary hospital in Tanzania. Hypertensive heart disease was defined as presence of increased LV mass or relative wall thickness (RWT). RESULTS. The prevalence of hypertensive heart disease increased with the severity of hypertension and was on average 62.1% among patients and 12.5% in controls. In multivariate analyses, higher LV mass index was associated with higher systolic blood pressure (β = 0.28), body mass index (β = 0.20), peak early transmitral to medial mitral annulus velocity ratio (β = 0.16), and with lower stress-corrected midwall shortening (scMWS) (β = - 0.44) and estimated glomerular filtration rate (β = - 0.16), all p < 0.05. Higher RWT was associated with higher systolic blood pressure (β = 0.16), longer E-wave deceleration time (β = 0.23) and lower scMWS (β = - 0.66), irrespective of LV mass (all p < 0.05). CONCLUSION. Subclinical hypertensive heart disease is highly prevalent in untreated native hypertensive Tanzanians and associated with both systolic and diastolic LV dysfunction. Management of hypertension in Africans should include high focus on subclinical hypertensive heart disease.

Revisiting the prehypertension debate: increasing evidence for treatment yet randomized clinical trials are lacking

In 2009, Blood Pressure featured a debate about whether to treat patients with prehypertension (Kiely et al., Blood Press. 2009;18:300-303; McInnes GT, Blood Press. 2009;18:304-307). Our group supported pharmacotherapy for this condition at that time. Since then, additional evidence linking prehypertension with associated morbidities has emerged. These studies are detailed below and provide further evidence for the treatment of prehypertension.

Phylloquinone and vitamin D status: associations with incident chronic kidney disease in the Framingham Offspring cohort

BACKGROUND

Cardiovascular risk factors are associated with the development of chronic kidney disease (CKD), and CKD and vascular disease are etiologically linked. Evidence suggests deficiencies of vitamins D and K may adversely affect the cardiovascular system, but data from longitudinal studies are lacking. We hypothesized that deficiencies of vitamins D and K may be associated with incident CKD and/or incident albuminuria amongst members of the general population.

METHODS

We analyzed 1,442 Framingham Heart Study participants (mean age 58 years; 50.5% women), free of CKD (eGFR <60 ml/min/1.73 m(2)), with a mean follow-up of 7.8 years in 2005-2008. Incident albuminuria was defined using sex-specific cut-offs of urine albumin-to-creatinine ratio (≥17 mg/g men and ≥25 mg/g women). Baseline log plasma phylloquinone (vitamin K(1)) and 25(OH)D levels, analyzed as continuous variables and by quartile, were related to risk of incident CKD (n = 108) and incident albuminuria (n = 106) using logistic regression models adjusted for standard risk factors.

RESULTS

Participants in the highest phylloquinone quartile (≥1.78 nmol/l) had an increased risk of CKD (multivariable-adjusted OR Q(4) vs. Q(1) 2.39; p = 0.006) and albuminuria at follow-up (multivariable-adjusted OR Q(4) vs. Q(1) 1.95; p = 0.05), whereas no association was observed with continuous phylloquinone levels for either endpoint. Deficiency of 25(OH)D was not associated with incident CKD or albuminuria in either analysis.

CONCLUSIONS

Contrary to our hypothesis, higher plasma phylloquinone levels are associated with an increased risk of incident CKD. Whether plasma phylloquinone is a marker for another unmeasured risk factor requires further study. External validation is necessary given the unexpected nature of these results.

A risk score for chronic kidney disease in the general population

BACKGROUND

Stratification of individuals at risk for chronic kidney disease may allow optimization of preventive measures to reduce disease incidence and complications. We sought to develop a risk score that estimates an individual's absolute risk of incident chronic kidney disease.

METHODS

Framingham Heart Study participants free of baseline chronic kidney disease, who attended a baseline examination in 1995-1998 and follow-up in 2005-2008, were included in the analysis (n = 2490). Chronic kidney disease was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2) using the Modification of Diet in Renal Disease equation. Participants were assessed for the development of chronic kidney disease at 10 years follow-up. Stepwise logistic regression was used to identify chronic kidney disease risk factors, and these were used to construct a risk score predicting 10-year chronic kidney disease risk. Performance characteristics were assessed using calibration and discrimination measures. The final model was externally validated in the bi-ethnic Atherosclerosis Risk in Communities Study (n = 1777).

RESULTS

There were 1171 men and 1319 women at baseline, and the mean age was 57.1 years. At follow-up, 9.2% (n = 229) had developed chronic kidney disease. Age, diabetes, hypertension, baseline estimated glomerular filtration rate, and albuminuria were independently associated with incident chronic kidney disease (P <.05), and these covariates were incorporated into a risk function (c-statistic 0.813). In external validation in the ARIC study, the c-statistic was 0.74 in whites (n = 1353) and 0.75 in blacks (n = 424).

CONCLUSION

Risk stratification for chronic kidney disease is achievable using a risk score derived from clinical factors that are readily accessible in primary care. The utility of this score in identifying individuals in the community at high risk of chronic kidney disease warrants further investigation.

Association of apolipoprotein A1 and B with kidney function and chronic kidney disease in two multiethnic population samples

BACKGROUND

Circulating lipoproteins and their protein constituents, apolipoproteins, are risk factors for chronic kidney disease (CKD). The associations between apolipoprotein A1, apolipoprotein B and their ratio with glomerular filtration rate estimated from the new CKD Epidemiology Collaboration (CKD-EPI) equation (eGFR) are not well studied in the general population.

METHODS

Associations between apolipoprotein A1, B and their ratio with the outcomes of eGFR, CKD (eGFR<60 mL/min/1.73 m2) and albuminuria were examined in the Atherosclerosis Risk in Communities study (ARIC, n=10,292, 1996-98) and the Third National Health and Nutrition Examination Survey (NHANES III, n=7023, 1988-91). Cross-sectional multivariable-adjusted analyses were performed using linear and logistic regression. Prospective analyses related baseline apolipoprotein levels to subsequent CKD incidence over 10 years using the ARIC Carotid MRI follow-up cohort (n=1659).

RESULTS

Higher apolipoprotein A1 quartiles were associated with a lower prevalence of CKD [Q4 versus Q1: odds ratio (OR) 0.73, P-trend=0.02 in ARIC; Q4 versus Q1: OR 0.53, P-trend<0.01 in NHANES III] as well as with higher eGFR (P-trend<0.01 in ARIC and NHANES III). No consistent significant associations were found for apolipoprotein B in either study. The apolipoprotein B/A1 ratio was significantly associated with eGFR across quartiles in both studies (P-trend<0.01) and with CKD in ARIC (Q4 versus Q1: OR 1.23, P-trend=0.01). Prospectively, there were trends for the association of apolipoproteins with incident CKD [Q4 versus Q1: incidence rate ratio (IRR)=0.68 for apolipoprotein A1, P-trend=0.1; Q4 versus Q1: IRR=1.35 for apolipoprotein B, P-trend=0.2]. Associations were not systematically stronger when comparing traditional lipids (total cholesterol, low-density lipoprotein or high-density lipoprotein) to apolipoproteins.

CONCLUSIONS

Higher serum apolipoprotein A1 was associated with lower prevalence of CKD and higher eGFR estimated by the CKD-EPI equation in two large multiethnic population-based samples. While apolipoprotein B showed no consistent associations, a higher apolipoprotein B/A1 ratio was significantly associated with lower eGFR in both studies. The direction and magnitude of the longitudinal associations between apolipoproteins and CKD incidence were overall similar to those observed cross-sectionally. No consistent differences became apparent between traditional lipids and apolipoproteins.

Urinary albumin-to-creatinine ratio in a first-morning void urine and prehypertension among Chinese Han women

BACKGROUND

This study was operated to investigate the association between urinary albumin-to-creatinine ratio (ACR) and prehypertension among Chinese Han women.

METHODS

Information on blood pressure measurement and other variables were obtained, and blood and urine samples collected in 1796 women aged ≥30 years. The association between urinary ACR and prehypertension were analyzed by using multivariate non-conditional logistic regression models.

RESULTS

Average urinary ACR was higher in hypertensives than in prehypertensives (median: 15.54 vs 9.01 mg/g), and in prehypertensives than in normotensives (median: 9.01 vs 7.13 mg/g). Both systolic and diastolic blood pressures increased with urinary ACR. Compared with the lowest quartile of urinary ACR, multivariate adjusted odds ratios of prehypertension were 1.25 (95% confidence interval, 0.89-1.78), 1.95 (1.30-2.92) and 1.59 (1.02-2.48) for the second, third and fourth quartiles, respectively. After exclusion of subjects with diabetes or use of antihypertensive medication, the odds ratio of prehypertension still increased with urinary ACR levels.

CONCLUSION

Increased urinary ACR was significantly and positively associated with prehypertension among Chinese Han women.

Effects of race on albuminuria and risk of cardiovascular and kidney disease

The literature describing the relationship between urinary protein excretion and risk of cardiovascular disease and renal disease is rapidly proliferating. Several studies have demonstrated racial differences in the relationship between albuminuria and associated disorders. The purpose of this article is to summarize the effects of race on the relationship between albuminuria and renal and cardiovascular disease risk, propose explanatory hypotheses, and suggest directions for future investigation.

The progressive pathway of microalbuminuria: from early marker of renal damage to strong cardiovascular risk predictor

There is clear evidence that urinary albumin excretion levels, even below the cut-off values currently used to diagnose microalbuminuria, are associated with an increased risk of cardiovascular events. The relationships of microalbuminuria with a variety of risk factors, such as hypertension, diabetes and metabolic syndrome and with several indices of subclinical organ damage, may contribute, at least in part, to explain the enhanced cardiovascular risk conferred by microalbuminuria. Nonetheless, several studies showed that the association between microalbuminuria and cardiovascular disease remains when all these risk factors are taken into account in multivariate analyses. Therefore, the exact pathophysiological mechanisms explaining the association between microalbuminuria and cardiovascular risk remain incompletely understood. The simple search for microalbuminuria in hypertensive patients may enable the clinician to better assess absolute cardiovascular risk, and its identification may induce physicians to encourage patients to make healthy lifestyle changes and perhaps would prompt to more aggressive modification of standard cardiovascular risk factors.

High-normal albuminuria and risk of heart failure in the community

BACKGROUND

Albuminuria has been associated with cardiovascular risk, but the relationship of high-normal albuminuria to subsequent heart failure has not been well established.

STUDY DESIGN

Prospective observational study, the Atherosclerosis Risk in Communities (ARIC) Study.

SETTING & PARTICIPANTS

10,975 individuals free from heart failure were followed up from the fourth ARIC Study visit (1996-1998) through January 2006.

PREDICTOR

Urinary albumin-creatinine ratio (UACR), analyzed continuously and categorically as optimal (<5 mg/g), intermediate-normal (5-9 mg/g), high-normal (10-29 mg/g), microalbuminuria (30-299 mg/g), and macroalbuminuria (≥300 mg/g).

OUTCOMES & MEASUREMENTS

Incident heart failure was defined as a heart failure-related hospitalization or death. Cox proportional hazard models were used to calculate the HR of heart failure after adjustment for age, race, sex, estimated glomerular filtration rate (eGFR), and other cardiovascular risk factors.

RESULTS

Individuals were followed up for a median of 8.3 years and experienced 344 heart failure events. Compared with normal UACR, albuminuria was associated with a progressively increased risk of heart failure from intermediate-normal (adjusted HR, 1.54; 95% CI, 1.12-2.11) and high-normal UACR (adjusted HR, 1.91; 95% CI, 1.38-2.66) to microalbuminuria (adjusted HR, 2.49; 95% CI, 1.77-3.50) and macroalbuminuria (adjusted HR, 3.47; 95% CI, 2.10-5.72). Results were similar in secondary analyses of participants censored at the time of coronary heart disease event and along a range of eGFRs.

LIMITATIONS

UACR was measured as a single random sample.

CONCLUSIONS

Albuminuria is associated with subsequent heart failure, even in individuals with few cardiovascular risk factors and UACR within the normal range. Our results suggest that the association between albuminuria and heart failure may not be mediated fully by ischemic heart disease or kidney disease, measured using eGFR.

CUBN is a gene locus for albuminuria

Identification of genetic risk factors for albuminuria may alter strategies for early prevention of CKD progression, particularly among patients with diabetes. Little is known about the influence of common genetic variants on albuminuria in both general and diabetic populations. We performed a meta-analysis of data from 63,153 individuals of European ancestry with genotype information from genome-wide association studies (CKDGen Consortium) and from a large candidate gene study (CARe Consortium) to identify susceptibility loci for the quantitative trait urinary albumin-to-creatinine ratio (UACR) and the clinical diagnosis microalbuminuria. We identified an association between a missense variant (I2984V) in the CUBN gene, which encodes cubilin, and both UACR (P = 1.1 × 10(-11)) and microalbuminuria (P = 0.001). We observed similar associations among 6981 African Americans in the CARe Consortium. The associations between this variant and both UACR and microalbuminuria were significant in individuals of European ancestry regardless of diabetes status. Finally, this variant associated with a 41% increased risk for the development of persistent microalbuminuria during 20 years of follow-up among 1304 participants with type 1 diabetes in the prospective DCCT/EDIC Study. In summary, we identified a missense CUBN variant that associates with levels of albuminuria in both the general population and in individuals with diabetes.

Lower urinary connective tissue growth factor levels and incident CKD stage 3 in the general population

BACKGROUND

Connective tissue growth factor (CTGF) is involved in the development and progression of kidney diseases, including diabetic nephropathy and kidney fibrosis, but also may have a role in mesangial repair after injury. It is unknown whether, in the general population, urinary CTGF levels are associated with a decrease in estimated glomerular filtration rate (eGFR) to <60 mL/min/1.73 m(2) (ie, development of chronic kidney disease [CKD] stage 3).

STUDY DESIGN

Nested case-control.

SETTING & PARTICIPANTS

100 cases of incident CKD stage 3 and 100 age-and sex-matched controls in the Framingham Heart Study; 141 cases and 135 age-, sex-, and race-matched controls in the Atherosclerosis Risk in Communities (ARIC) Study. Controls had eGFR ≥60 mL/min/1.73 m(2) at follow-up in both studies.

PREDICTORS

Urinary CTGF concentrations.

OUTCOMES

Incident CKD stage 3, defined as eGFR <60 mL/min/1.73 m(2).

MEASUREMENTS

Stored urine samples from Framingham Heart Study and ARIC were measured for CTGF. Covariates were obtained from Framingham Heart Study and ARIC participant examinations.

RESULTS

In the Framingham Heart Study, the median baseline urinary CTGF concentration was lower in cases (1.35 ng/mL) than controls (2.35 ng/mL; paired t test, P < 0.0001). The multivariable-adjusted OR for incident CKD stage 3 was 0.33 (95% CI, 0.17-0.64; P < 0.001) per 1-standard deviation in log urinary CTGF level after adjustment for CKD risk factors, baseline eGFR, and baseline log urinary albumin-creatinine ratio, with similar results in participants without diabetes (n = 184). Results were not materially different when urinary CTGF level was indexed to urinary creatinine level (multivariable-adjusted OR, 0.34; 95% CI, 0.21-0.56; P < 0.001). A similar, but nonsignificant, trend of risk of incident CKD stage 3 with lower baseline urinary CTGF concentration was observed in an independent case-control study conducted in the ARIC Study, with the strongest results observed in participants free of diabetes. This inverse relationship was robust in meta-analysis of both the overall and diabetes-free groups.

LIMITATIONS

Observational study; causality cannot be inferred.

CONCLUSIONS

Lower urinary CTGF concentrations precede the onset of CKD stage 3 in the general population. Further work is required to fully characterize how CTGF level influences risk of CKD.

Albuminuria and estimated glomerular filtration rate independently associate with acute kidney injury

Acute kidney injury (AKI) is increasingly common and a significant contributor to excess death in hospitalized patients. CKD is an established risk factor for AKI; however, the independent graded association of urine albumin excretion with AKI is unknown. We analyzed a prospective cohort of 11,200 participants in the Atherosclerosis Risk in Communities (ARIC) study for the association between baseline urine albumin-to-creatinine ratio and estimated GFR (eGFR) with hospitalizations or death with AKI. The incidence of AKI events was 4.0 per 1000 person-years of follow-up. Using participants with urine albumin-to-creatinine ratios <10 mg/g as a reference, the relative hazards of AKI, adjusted for age, gender, race, cardiovascular risk factors, and categories of eGFR were 1.9 (95% CI, 1.4 to 2.6), 2.2 (95% CI, 1.6 to 3.0), and 4.8 (95% CI, 3.2 to 7.2) for urine albumin-to-creatinine ratio groups of 11 to 29 mg/g, 30 to 299 mg/g, and ≥300 mg/g, respectively. Similarly, the overall adjusted relative hazard of AKI increased with decreasing eGFR. Patterns persisted within subgroups of age, race, and gender. In summary, albuminuria and eGFR have strong, independent associations with incident AKI.

Prevalence of chronic kidney disease in persons with undiagnosed or prehypertension in the United States

Hypertension is both a cause and a consequence of chronic kidney disease, but the prevalence of chronic kidney disease throughout the diagnostic spectrum of blood pressure has not been established. We determined the prevalence of chronic kidney disease within blood pressure categories in 17 794 adults surveyed by the National Health and Nutrition Examination Survey during 1999-2006. Diagnosed hypertension was defined as self-reported provider diagnosis (n=5832); undiagnosed hypertension was defined as systolic blood pressure > or = 140 mm Hg or diastolic blood pressure > or = 90 mm Hg, without report of provider diagnosis (n=3046); prehypertension was defined as systolic blood pressure > or = 120 and <140 mm Hg or diastolic blood pressure > or = 80 and <90 mm Hg (n=3719); and normal was defined as systolic blood pressure <120 mm Hg and diastolic blood pressure <80 mm Hg (n=5197). Chronic kidney disease was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m(2) or urinary albumin:creatinine ratio >30 mg/g. Prevalences of chronic kidney disease among those with prehypertension and undiagnosed hypertension were 17.3% and 22.0%, respectively, compared with 27.5% with diagnosed hypertension and 13.4% with normal blood pressure, after adjustment for age, sex, and race in multivariable logistic regression. This pattern persisted with varying definitions of kidney disease; macroalbuminuria (urinary albumin:creatinine ratio >300 mg/g) had the strongest association with increasing blood pressure category (odds ratio: 2.37 [95% CI: 2.00 to 2.81]). Chronic kidney disease is prevalent in undiagnosed and prehypertension. Earlier identification and treatment of both these conditions may prevent or delay morbidity and mortality from chronic kidney disease.