Microalbuminuria as a predictive factor for cardiovascular events

Biomarkers of high salt intake

High salt intake is associated with hypertension, which is a leading modifiable risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). International Guidelines recommend a large reduction in the consumption of sodium to reduce blood pressure, organ damage, and mortality. In its early stages, the symptoms of CKD are generally not apparent. CKD proceeds in a "silent" manner, necessitating the need for urinary biomarkers to detect kidney damage at an early stage. Since traditional renal biomarkers, such as serum creatinine, are not sufficiently sensitive, difficulties are associated with detecting kidney damage induced by a high salt intake, particularly in normotensive individuals. Several new biomarkers for renal tubular damage, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), vanin-1, liver-type fatty acid-binding protein (L-FABP), and monocyte chemotactic protein-1 (MCP-1), have recently been identified. However, few studies have investigated early biomarkers for CKD progression associated with a high salt diet. This chapter provides insights into novel biomarkers for CKD in normo- and hypertensive individuals with a high salt intake. Recent studies using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high salt diet identified urinary vanin-1 and NGAL as early biomarkers for renal tubular damage in SHR and WKY, whereas urinary KIM-1 was a useful biomarker for salt-induced renal injury in SHR only. Clinical studies are needed to confirm these findings.

Past Sodium Intake, Contemporary Sodium Intake, and Cardiometabolic Health in Southwest Coastal Bangladesh

Background We compared the relationship of past and contemporary sodium (Na) intake with cardiometabolic biomarkers. Methods and Results A total of 1191 participants' data from a randomized controlled trial in coastal Bangladesh were analyzed. Participants provided 24-hour urine Na (24UNa) data for 5 monthly visits. Their fasting blood glucose, total cholesterol, triglycerides, high-density lipoprotein, blood pressure, and 24-hour urine protein were measured at the fifth visit. Participants' mean 24UNa over the first 4 visits was the past Na, and 24UNa of the fifth visit was the contemporary Na intake. We estimated the prevalence ratios of elevated cardiometabolic biomarkers and metabolic syndrome across 24UNa tertiles by multilevel logistic regression using participant-, household-, and community-level random intercepts. Models were adjusted for age, sex, body mass index, smoking, physical activity, alcohol consumption, sleep hours, religion, and household wealth. Compared with participants in tertile 1 of past urine Na, those in tertile 3 had 1.46 (95% CI, 1.08-1.99) times higher prevalence of prediabetes or diabetes mellitus, 5.49 (95% CI, 2.73-11.01) times higher prevalence of large waist circumference, and 1.60 (95% CI, 1.04-2.46) times higher prevalence of metabolic syndrome. Compared with participants in tertile 1 of contemporary urine Na, those in tertile 3 had 1.93 (95% CI, 1.24-3.00) times higher prevalence of prediabetes or diabetes mellitus, 3.14 (95% CI, 1.45-6.83) times higher prevalence of proteinuria, and 2.23 (95% CI, 1.34-3.71) times higher prevalence of large waist circumference. Conclusions Both past and contemporary Na intakes were associated with higher cardiometabolic disease risk.

Stepped-wedge cluster-randomised controlled trial to assess the cardiovascular health effects of a managed aquifer recharge initiative to reduce drinking water salinity in southwest coastal Bangladesh: study design and rationale

INTRODUCTION

Saltwater intrusion and salinisation have contributed to drinking water scarcity in many coastal regions globally, leading to dependence on alternative sources for water supply. In southwest coastal Bangladesh, communities have few options but to drink brackish groundwater which has been associated with high blood pressure among the adult population, and pre-eclampsia and gestational hypertension among pregnant women. Managed aquifer recharge (MAR), the purposeful recharge of surface water or rainwater to aquifers to bring hydrological equilibrium, is a potential solution for salinity problem in southwest coastal Bangladesh by creating a freshwater lens within the brackish aquifer. Our study aims to evaluate whether consumption of MAR water improves human health, particularly by reducing blood pressure among communities in coastal Bangladesh.

METHODS AND ANALYSIS

The study employs a stepped-wedge cluster-randomised controlled community trial design in 16 communities over five monthly visits. During each visit, we will collect data on participants' source of drinking and cooking water and measure the salinity level and electrical conductivity of household stored water. At each visit, we will also measure the blood pressure of participants ≥20 years of age and pregnant women and collect urine samples for urinary sodium and protein measurements. We will use generalised linear mixed models to determine the association of access to MAR water on blood pressure of the participants.

ETHICS AND DISSEMINATION

The study protocol has been reviewed and approved by the Institutional Review Boards of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b). Informed written consent will be taken from all the participants. This study is funded by Wellcome Trust, UK. The study findings will be disseminated to the government partners, at research conferences and in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02746003; Pre-results.

Prevalence and risk factors of microalbuminuria in Thai nondiabetic hypertensive patients

PURPOSE

To assess the prevalence and risk factors of microalbuminuria in nondiabetic hypertensive patients in Thailand.

PATIENTS AND METHODS

A cross-sectional study was performed during January to December 2007 at outpatients departments of Bhumibol Adulyadej hospital. Nondiabetic hypertensive patients without a history of pre-existing kidney diseases participated in this study. A questionnaire was used for collecting information on demographics, lifestyle, and family history of cardiovascular and kidney disease. Spot morning urine samples were collected for albuminuria estimation. Albuminuria thresholds were evaluated and defined using albumin-creatinine ratio (ACR).

RESULTS

A total of 559 hypertensive patients (283 males, 276 females), aged 58.0 +/- 11.6 years were enrolled in this study. Microalbuminuria (ACR 17 to 299 mg/g in males and 25 to 299 mg/g in females) was found in 93 cases (16.6%) [15.0%-18.2%]. The independent determinants of elevated urinary albumin excretion in a multiple logistic regression model were; body mass index > or =30 (odds ratio (OR) = 2.24, 95% confidence intervals (CI): 1.33-3.76) and dihydropyridine calcium channel blockers (DCCB) use (OR = 1.92, 95% CI: 1.22-3.02).

CONCLUSION

In Thai nondiabetic hypertensive patients, microalbuminuria was not uncommon. Obesity and use of dihydropyridine calcium channel blocker were found to be the important predictors. Prognostic value of the occurrence of microalbuminuria in this population remains to be determined in prospective cohort studies.

Clinical effects of calcium channel blocker and Angiotensin converting enzyme inhibitor on endothelial function and arterial stiffness in patients with angina pectoris

To evaluate the effects of calcium channel blocker (CCB) and angiotensin converting enzyme inhibitor (ACEI) on endothelial function and arterial stiffness in stable angina pectoris (SAP), 87 patients with SAP (57.6+/-10.0 yr, 52 males) were divided into two groups; CCB group (group I: n=44, 57.9+/-9.7 yr, 23 males) vs. CCB plus ACEI group (group II: n=43, 57.2+/-10.5 yr, 29 males). Flow mediated vasodilation (FMD) of the brachial artery, pulse wave velocity (PWV), urinary albumin excretion (UAE), and high sensitivity C-reactive protein (hsCRP) were compared. FMD, PWV, UAE, and hsCRP were not different between the groups at baseline. After 6 months of treatment, FMD were significantly improved in group II (7.5+/-3.7 to 8.8+/-2.7%, p<0.001), but not in group I (7.9+/-2.7 to 8.2+/-2.8%, p=0.535). Brachial-ankle PWV were significantly improved in both groups (1,621.3+/-279.4 to 1,512.1+/-225.0 cm/sec in group I, p<0.001, 1,586.8+/-278.5 to 1,434.5+/-200.5 cm/sec in group II, p<0.001). However, heart-femoral PWV were significantly improved (1,025.7+/-145.1 to 946.2+/-112.2 cm/sec, p<0.001) and UAE were significantly decreased (20.19+/-29.92 to 13.03+/-16.42 mg/g Cr, p=0.019) in group II only. In conclusion, combination therapy with CCB and ACEI improves endothelial function, arterial stiffness, and UAE than CCB mono-therapy more effectively in patients with SAP.

Microalbuminuria in Thai essential hypertensive patients

Essential hypertensive patients (176 males and 329 females), aged 58.0+/-11.2 years were enrolled in a cross-sectional study conducted from February to March 2006 to investigate the prevalence and risk factors for microalbuminuria in hypertensive patients attending the Outpatient Department of Siriraj Hospital, Bangkok, Thailand. Macroalbuminuria was detected in 11 (2.2%) patients and microalbuminuria in 94 (18.6%) patients. Only male aged>or=45 years or female aged>or=55 years correlated significantly with a high occurrence of microalbuminuria, while calcium channel blocker and statin users were protected against microalbuminuria. The presence of microalbuminuria was not associated with age>or=60 years, male gender, current/previous smokers, hypertension duration>or=10 years, lack of blood pressure normalization, metabolic syndrome, use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and multi-drug use. Risk factor recognition for microalbuminuria will enable physicians to identify cases that should be screened for microalbuminuria.

Metabolic syndrome and incident end-stage peripheral vascular disease: a 14-year follow-up study in elderly Finns

OBJECTIVE

We investigated the relationship of the metabolic syndrome and its single components, defined by four different criteria, with peripheral vascular disease (PVD) in a prospective population-based study.

RESEARCH DESIGN AND METHODS

The metabolic syndrome was defined according to the World Health Organization (WHO), the National Cholesterol Education Program (NCEP), the International Diabetes Federation (IDF), and the American Heart Association (updated NCEP) criteria. We investigated the relationship of the metabolic syndrome defined by the aforementioned four criteria with PVD (revacularization and amputation) by Cox regression analyses in a Finnish population of 1,212 subjects, aged 65-74 years, with and without diabetes during a 14-year follow-up.

RESULTS

The metabolic syndrome defined by the WHO, NCEP, and updated NCEP criteria was associated with a statistically significant risk for incident PVD (n = 57) with adjustment for all confounding variables except for prevalent diabetes (hazard ratios [HRs] from 1.91 to 2.62). After adjustment for prevalent diabetes or after the exclusion of subjects with prevalent diabetes, there was no association between the metabolic syndrome by any criteria and incident PVD. Of the single components of the metabolic syndrome, elevated fasting glucose by the WHO and NCEP criteria (HR 2.35) and microalbuminuria by the WHO definition (2.56) predicted PVD in multivariable models (prevalent diabetes included).

CONCLUSIONS

The metabolic syndrome defined by the WHO, NCEP, and updated NCEP criteria predicted incident end-stage PVD in elderly Finns but only when not adjusted for diabetes status. Two of the single components of the metabolic syndrome, elevated fasting plasma glucose and microalbuminuria, predicted PVD. We conclude that the metabolic syndrome predicts PVD but not above and beyond the risk associated with diabetes and microalbuminuria.

Potential mechanisms of stroke benefit favoring losartan in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study

INTRODUCTION

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study is the first, and, so far, the only endpoint trial in patients with hypertension and left ventricular hypertrophy (LVH) to show a divergent therapeutic outcome of one treatment modality over another with equivalent blood pressure control. The purpose of this article is to review post hoc sub-analyses of LIFE study data and other clinical studies that offer some insight into possible treatment-related differences contributing to the superior stroke outcome of losartan versus atenolol beyond blood pressure reduction.

METHODS

Relevant randomized clinical trials and review articles were identified through a MEDLINE search of English-language articles published between 1990 and 2006 using the search terms losartan, atenolol, LIFE, hypertension, and LVH. Articles describing major clinical studies, new data, or mechanisms pertinent to the LIFE study were selected for review.

RESULTS

Differences in blood pressure or in the distribution of add-on medications were not evident between study groups in the LIFE study. Thus, the observed outcomes benefits favoring losartan may involve other possible mechanisms, including differential effects of losartan and atenolol on LVH regression, left atrial diameter, atrial fibrillation, brain natriuretic peptide, vascular structure, thrombus formation/platelet aggregation, serum uric acid, albuminuria, new-onset diabetes, and lipid metabolism. Alternative explanations for the LIFE study findings have also been put forward, including the choice of atenolol as an appropriate active comparator and differential effects between treatment groups on central pulse pressure. Additional clinical trials are needed to determine if the beneficial effects of losartan seen in LIFE are shared by other inhibitors of the renin-angiotensin system.

CONCLUSION

Sub-analyses of the LIFE study data suggest that losartan's stroke benefit may arise from a mosaic of mechanisms rather than a single action. Further studies are expected to continue to delineate the mechanisms of differential responses to treatments in LIFE.

Funduscopic Examination Has Limited Benefit for Management of Hypertension

Hypertension (HT) increases the risks of major cardiovascular events and affects a majority of elderly populations. Thus, blood pressure control is the mainstay for prevention of cardiovascular diseases. However, there is only a limited number of parameters for management of HT. This study was performed on consecutive patients between the ages of 35 and 70 years with normotension (NT) and HT in order to determine the possible consequences of HT on retinal vasculature and to avoid debility-induced weight loss. We studied 120 patients (64 females, 54.3 +/- 9.3 years) with NT and 147 (81 females, 57.3 +/- 11.0 years) with HT. No case of grade III or IV hypertensive retinopathy (HR) was detected in the groups. Although the prevalences of grades I and II HR were higher and grade 0 HR was lower in the hypertensive group, respectively (P < 0.001 for all), differences according to obesity, diabetes mellitus, hypertriglyceridemia (P < 0.001 for all), and dyslipidemia (P < 0.01) were also significant between the 2 groups. Therefore, only 18.3% (27 cases) of the hypertensives, even in whom the effect of aging could not be excluded, had HT only in the absence of any other risk factor of atherosclerosis. Despite the relatively higher specificities of grades III and IV HR for HT, particularly for hypertensive crisis, funduscopic examination has limited benefit in the management of HT due to the very low prevalences of grades III and IV HR, the multifactorial backgrounds of grades I and II HR, and the association of the multiple risk factors of atherosclerosis in a majority of the hypertensive cases.

Factors Related to Microalbuminuria in Nondiabetic Elderly Males with Normal Renal Function

Two hundred and three adult males were evaluated for the presence of microalbuminuria. Out of 203 patients, 123 (61%) tested negative for microalbuminuria and 80 (39%) tested positive. Patients were further evaluated for age, body mass index, cigarette smoking, blood pressure, serum lipid levels, renal function, cardiovascular events, and use of antihypertensive and antihyperlipidemic medications. This study shows that age greater than 70 years, creatinine clearance less than 50 mL/min, and systolic blood pressure greater than or equal to 140 mm Hg are all significant risk factors for microalbuminuria.

Do angiotensin II antagonists provide benefits beyond blood pressure reduction?

Hypertension is a powerful risk factor for cardiovascular (CV) morbidity and mortality; therefore, blood pressure (BP) lowering plays a central role in reducing the cardiovascular complications of hypertension, including stroke. Recent outcomes studies--Losartan Intervention For Endpoint reduction in hypertension, Reduction of Endpoints in Non-insulin-dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan, and the Irbesartan Type 2 Diabetic Nephropathy Trial--suggest that some angiotensin II antagonists are associated with CV and renal effects beyond their ability to lower BP in patients with hypertension or diabetic nephropathy and may play a role in the prevention of new-onset type 2 diabetes. Angiotensin II antagonists are associated with a wide variety of vascular, cardiac, and renal effects, as well as molecule-specific effects independent of those induced by the angiotensin-I receptor. These actions may offer a mechanistic explanation for the outcome benefits observed in patients with hypertension or diabetic nephropathy. Angiotensin-converting enzyme inhibitors and calcium-channel blockers may also have effects that are not completely explained by differences in the antihypertensive response to these agents, but the evidence is less robust. Collectively, these findings suggest that management of patients with hypertension, with or without diabetes or renal disease, should no longer be viewed as simply a matter of correcting elevated BP. Antihypertensive agents that possess CV benefits beyond their BP-reducing effects should be used to prevent the development of end-organ damage.

Prevention and treatment of stroke in patients with hypertension

BACKGROUND

Each year, stroke occurs in 30.9 million individuals worldwide and is responsible for approximately 4 million deaths. In the United States, it is the third leading cause of death, occurring with greater frequency than myocardial infarction in patients with hypertension. The greatest burden of stroke, apart from death, is serious long-term physical and mental disability. Stroke survivors often experience physical handicap, depression, and cognitive dysfunction, which together affect their daily functioning, quality of life, and survival. The treatment of stroke is associated with extremely high costs, with stroke-related illnesses responsible for >$49 billion in the United States in 2002. Despite intensive research efforts, few effective treatments are available once stroke has occurred; thus, stroke prevention should be a primary focus for all health care providers.

OBJECTIVE

The purpose of this article was to review the epidemiology and burden of stroke in terms of disability, quality of life, and cost of care, and to summarize the evidence for treatments having therapeutic benefit, with an emphasis on antihypertensive agents.

METHODS

Relevant studies were identified through a MEDLINE search of English-language articles published between 1990 and 2004. The search terms were stroke, epidemiology, economic impact, disability, quality of life, hypertension, drug therapy, and angiotensin II-receptor antagonists. Articles describing major clinical studies, new data, or new mechanisms pertinent to the therapy of stroke were selected for review.

CONCLUSIONS

Identifying and modifying key risk factors is crucial to reducing the morbidity and mortality of stroke. Hypertension is one of the most important risk factors for stroke, and treatment with a variety of antihypertensive agents reduces the risk. Recent evidence suggests that the angiotensin II (ATII)-receptor antagonist losartan may offer advantages beyond blood pressure lowering, including attenuation of the central aortic reflected pressure wave, molecule-specific properties, and neural protective influences on brain ATII type 2 receptors.

Higher urinary albumin excretion is associated with abnormal erythrocyte Na(+)/Li(+) countertransport (SLC) in non-modulating essential hypertensives and offspring of hypertensive parents

Non-modulating is a highly reproducible type of sodium-sensitive hypertension. The aim of this study was to evaluate in non-modulating individuals the erythrocyte sodium-lithium countertransport (SLC) abnormalities, which have been mentioned as a marker of non-modulation, and the association with increased microalbuminuria, as a marker of an early kidney impairment. We measured erythrocyte SLC in 10 normotensives (NT, 28 +/- 4 years), 20 offspring of hypertensive parents being 10 modulating (MHO, 25 +/- 6 years) and 10 non-modulating (NMHO, 26 +/- 5 years), and 23 essential hypertensives being 12 modulating (MHT, 34 +/- 5 years) and 11 non-modulating (NMHT, 32 +/- 4 years). In all the subjects studied, microalbuminuria was determined by duplicate 24-h urine collection by radioimmunoassay. In non-modulating offspring of hypertensive parents and essential hypertensives. SLC was significantly elevated when compared either with normotensives without family history of hypertension, modulating offspring of hypertensive parents or essential hypertensives (P < 0.025). Likewise, 24-h urinary albumin excretion was found higher in non-modulating individuals (essential hypertensives and offspring of hypertensive parents) than in modulating individuals (P < 0.01). In conclusion, non-modulators with higher SLC countertransport sodium transport abnormalities showed higher elimination of microalbuminuria suggesting that non-modulators may have an increased risk for developing cardiovascular morbidity and kidney impairment even in normotensive subjects with familiarity history of hypertension.