Effect of inhibitors of the renin-angiotensin system and other antihypertensive drugs on renal outcomes: systematic review and meta-analysis

Reno-protective effects of renin-angiotensin system blockade in type 2 diabetic patients: a systematic review and network meta-analysis

AIMS/HYPOTHESIS

This meta-analysis aimed to compare the renal outcomes between ACE inhibitor (ACEI)/angiotensin II receptor blocker (ARB) and other antihypertensive drugs or placebo in type 2 diabetes.

METHODS

Publications were identified from Medline and Embase up to July 2011. Only randomised controlled trials comparing ACEI/ARB monotherapy with other active drugs or placebo were eligible. The outcome of end-stage renal disease, doubling of serum creatinine, microvascular complications, microalbuminuria, macroalbuminuria and albuminuria regression were extracted. Risk ratios were pooled using a random-effects model if heterogeneity was present; a fixed-effects model was used in the absence of heterogeneity.

RESULTS

Of 673 studies identified, 28 were eligible (n = 13-4,912). In direct meta-analysis, ACEI/ARB had significantly lower risk of serum creatinine doubling (pooled RR = 0.66 [95% CI 0.52, 0.83]), macroalbuminuria (pooled RR = 0.70 [95% CI 0.50, 1.00]) and albuminuria regression (pooled RR 1.16 [95% CI 1.00, 1.39]) than other antihypertensive drugs, mainly calcium channel blockers (CCBs). Although the risks of end-stage renal disease and microalbuminuria were lower in the ACEI/ARB group (pooled RR 0.82 [95% CI 0.64, 1.05] and 0.84 [95% CI 0.61, 1.15], respectively), the differences were not statistically significant. The ACEI/ARB benefit over placebo was significant for all outcomes except microalbuminuria. A network meta-analysis detected significant treatment effects across all outcomes for both active drugs and placebo comparisons.

CONCLUSIONS/INTERPRETATION

Our review suggests a consistent reno-protective effect of ACEI/ARB over other antihypertensive drugs, mainly CCBs, and placebo in type 2 diabetes. The lack of any differences in BP decrease between ACEI/ARB and active comparators suggest this benefit is not due simply to the antihypertensive effect.

WITHDRAWN: Enhanced cardio-renal protective effects of valsartan in high-risk hypertensive patients with chronic kidney disease: A sub-analysis of KYOTO HEART Study

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Treatment of hypertension with renin-angiotensin system inhibitors and renal dysfunction: a systematic review and meta-analysis

BACKGROUND

To determine whether inhibitors of the renin-angiotensin system (RAS) reduce the incidence of renal dysfunction when compared to other antihypertensive treatments in patients with essential hypertension and no pre-existent renal disease.

METHODS

The search strategy used the Cochrane Library, Medline, previous meta-analyses, and journal reviews. The selection criteria included randomized, controlled trials of antihypertensive drugs that compared a RAS inhibitor with another treatment in essential hypertension. Studies that specifically enrolled only patients with diabetes or renal disease were not included. The quality assessment and data extraction of studies were performed by two independent reviewers. Effects on dichotomous renal outcome (serum creatinine (SCreat) higher than a prespecified value, doubling of SCreat or end-stage renal disease) and secondary continuous marker of renal outcome (change in SCreat) were calculated using Peto's method.

RESULTS

33,240 patients met the inclusion criteria for studies with a dichotomous outcome and 10,634 patients for studies with a continuous outcome. The mean follow-up was 42 ± 13 months. Patients randomized to RAS inhibitors did not show a significant reduction in the risk of developing renal dysfunction as compared to other antihypertensive strategies (odds ratio = 1.05; 95% confidence interval (CI) 0.89-1.25; P = 0.54). There was no significant difference in change of SCreat between groups (mean difference = 0.0005 mg/dl; 95% CI -0.0068 to 0.0077 mg/dl; P = 0.91).

CONCLUSION

In patients with essential hypertension and no pre-existent renal disease, prevention of renal dysfunction is not significantly different with RAS inhibitors when compared to other antihypertensive agents.

Reduction in urinary albumin excretion with a moderate low-carbohydrate diet in patients with type 2 diabetes: a 12-month intervention

INTRODUCTION

Urinary albumin excretion (UAE) is a marker of the early phase of diabetic nephropathy. Although a low-carbohydrate diet (LCD) has been shown to effectively improve glycemic control in patients with type 2 diabetes (T2DM), its effects on UAE remain unknown.

PATIENTS AND METHODS

A total of 124 patients (mean age ± standard deviation, 61.6 ± 9.2 years) with T2DM were instructed to consume a moderate LCD (1734 ± 416 kcal/d; % carbohydrate:fat:protein = 38:37:19) for 12 months. We measured the levels of UAE, hemoglobin A(1c), fasting plasma glucose, fasting serum insulin (IRI), and the serum lipid profiles in the patients and recorded their dosages of antidiabetic drugs during this 12-month period.

RESULTS

Of the 124 patients, 68 were normoalbuminuric, 50 were microalbuminuric, and six were macroalbuminuric at baseline. The patients had relatively good compliance with the moderate LCD diet. After 12 months, the mean levels of hemoglobin A(1c), fasting plasma glucose, IRI, homeostasis model assessment-estimated insulin resistance, and the body mass index of all participants significantly decreased (P = 0.003 for IRI and P < 0.001 for the other parameters). Among the microalbuminuric patients (n = 50), remission to normoalbuminuria was frequently achieved (52%) and the geometric mean UAE significantly decreased by 53% (95% confidence interval: 43, 62) over 12 months (P < 0.001). After patients taking an angiotensin 2 receptor blocker were excluded, the UAE significantly decreased by 41% (n = 26, 95% confidence interval: 25, 54; P < 0.001). Moreover, the reduction in UAE was significantly and positively correlated with a reduction in homeostasis model assessment-estimated insulin resistance levels (r(s) = 0.308; P = 0.031).

CONCLUSION

A moderate LCD (38% carbohydrate diet) achieved a remarkable reduction in UAE over 12 months in microalbuminuric patients with T2DM.

The impact of renin-angiotensin-aldosterone system inhibitors on Type 1 and Type 2 diabetic patients with and without early diabetic nephropathy

Renin-angiotensin-aldosterone system inhibitors prevent the progression of kidney disease in patients with diabetic nephropathy, and we studied how that benefit varies by the type of diabetes and baseline urinary albumin. We pooled data from 49 randomized controlled trials in a meta-analysis using the ratio of endpoint urinary albumin levels in those treated compared to those untreated with renin-angiotensin-aldosterone system inhibitors in both fixed- and random-effects models. The urinary albumin excretion for treated microalbuminuric patients with Type 1 diabetes was on average 60% lower at the end of the trial compared with patients not treated with renin-angiotensin-aldosterone system inhibitors using the fixed-effects model and 67% lower using the random-effects model. There was no significant effect of treatment in patients with normal albumin excretion. For normoalbuminuric patients with Type 2 diabetes, urinary albumin excretion was on average 12% lower after treatment using the fixed-effects model compared to 21% lower using the random-effects model. For microalbuminuric patients, urinary albumin excretion was on average 23% lower using the fixed-effects model and 27% lower using the random-effects model. Thus, renin-angiotensin-aldosterone system inhibition reduced urinary albumin excretion for Type 1 diabetic patients with micro-, but not those with normoalbuminuria. Treatment reduced urinary albumin excretion for Type 2 diabetic patients with and without microalbuminuria.

Physiological function of the angiotensin AT1a receptor in bone remodeling

In order to determine whether the renin-angiotensin system (RAS) has any physiologic function in bone metabolism, mice lacking the gene encoding the major angiotensin II receptor isoform, AT1a, were studied using micro CT scanning, histomorphometric, and biochemical techniques. Three-dimensional (3D) micro CT analysis of the tibial metaphysis revealed that both male and female AT1a knockout mice exhibited an increased trabecular bone volume along with increased trabecular number and connectivity. Histomorphometric analysis of the tibial metaphysis indicated that the parameters of bone formation as well as resorption were increased, which was also supported by elevated serum osteocalcin and carboxy-terminal collagen crosslink (CTX) concentrations in the AT1a-deficient mice. Osteoclastogenesis and osteoblastogenesis assays in ex vivo cultures, however, did not reveal any intrinsic alterations in the differentiation potential of AT1a-deficient cells. Quantitative RT-PCR using RNA isolated from the tibia and femur revealed that the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) ratio and the expression of stromal cell-derived factor (SDF)1α were increased, whereas that of SOST was decreased in AT1a-deficient bone, which may account for the increased bone resorption and formation, respectively. AT1a-deficient mice also displayed a lean phenotype with reduced serum leptin levels. They maintained high bone mass with advancing age, and were protected from bone loss induced by ovariectomy. Collectively, the data suggest that RAS has a physiologic function in bone remodeling, and that signaling through AT1a negatively regulates bone turnover and bone mass.

Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers are beneficial in normotensive atherosclerotic patients: a collaborative meta-analysis of randomized trials

AIMS

It is unclear whether angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB) are beneficial in individuals with, or at increased risk for, atherosclerotic vascular disease who are normotensive.

METHODS AND RESULTS

Two investigators independently searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from 1980 to 2011, bibliographies, and contacted primary study authors for randomized placebo-controlled outcome trials evaluating ACE-I or ARB which enrolled at least 1000 patients with, or at increased risk for, atherosclerotic vascular disease and followed them for at least 12 months. We approached all eligible trials to obtain data stratified by baseline systolic pressures. We pooled data from 13 trials of 80 594 patients; outcomes included 9043 all-cause deaths, 5674 cardiovascular deaths, 3106 myocardial infarctions, and 4452 strokes. Angiotensin-converting enzyme inhibitors or ARB reduced the composite primary outcome of cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke by 11% (95% confidence interval 7-15%), with no variation in efficacy across baseline systolic blood pressure strata. In patients with baseline systolic pressure <130 mmHg, ACE-I or ARB reduced the composite primary outcome by 16% (10-23%) and all-cause mortality by 11% (4-18%)-this benefit was consistent across all subgroups examined including those without systolic heart failure (OR: 0.81, 95% CI: 0.75-0.88) and those without diabetes (OR: 0.79, 95% CI: 0.70-0.89).

CONCLUSION

Angiotensin-converting enzyme inhibitors or ARB are beneficial in patients with, or at increased risk for, atherosclerotic disease even if their systolic pressure is <130 mmHg before treatment.

Cost-effectiveness of angiotensin-converting enzyme inhibitors for the prevention of diabetic nephropathy in The Netherlands--a Markov model

OBJECTIVE

Type 2 diabetes is the main cause of end-stage renal disease (ESRD) in Europe and the USA. Angiotensin-converting enzyme (ACE) inhibitors have a potential to slow down the progression of renal disease and therefore provide a renal-protective effect. The aim of our study was to assess the most cost-effective time to start an ACE inhibitor (or an angiotensin II receptor blocker [ARB] if coughing as a side effect occurs) in patients with newly diagnosed type 2 diabetes in The Netherlands.

METHODS

A lifetime Markov decision model with simulated 50-year-old patients with newly diagnosed diabetes mellitus was developed using published data on costs and health outcomes and simulating the progression of renal disease. A health insurance perspective was adopted. Three strategies were compared: treating all patients at the time of diagnosing type 2 diabetes, screening for microalbuminuria, and screening for macroalbuminuria.

RESULTS

In the base-case analysis, the treat-all strategy is associated with the lowest costs and highest benefit and therefore dominates screening both for macroalbuminuria and microalbuminuria. A multivariate sensitivity analysis shows that the probability of savings is 70%.

CONCLUSIONS

In The Netherlands for patients with type 2 diabetes prescription of an ACE inhibitor immediately after diagnosis should be considered if they do not have contraindications. An ARB should be considered for those patients developing a dry cough under ACE inhibitor therapy. The potential for cost savings would be even larger if the prevention of cardiovascular events were considered.

Balancing calcium signals through TRPC5 and TRPC6 in podocytes

Calcium (Ca(2+)) ions are important mediators of cellular homeostasis owing to their ability to elicit a dynamic, transient, and tightly regulated range of biochemical responses. More than a decade ago, a nonselective, Ca(2+)-permeable, cationic conductance was identified in podocytes downstream of angiotensin II (Ang II) signaling, but its molecular structure remained elusive. Six years ago, transient receptor potential canonical 6 (TRPC6) mutations were found in families with hereditary FSGS, and TRPC5 and TRPC6 channels are now known as the Ca(2+) influx pathways for this previously described, nonselective, cationic current in podocytes. Ang II activation engages this Ca(2+) influx to modulate the actin cytoskeleton in podocytes. These discoveries dovetail with previously described regulation of actin dynamics by the Ca(2+)-activated phosphatase, calcineurin, and the emergence of Rho GTPases as critical regulators of podocyte function in health and disease. Understanding the interconnected signaling regulated by Ca(2+) currents offers potential new therapeutic targets and highlights the notion that synergistic therapies targeting multiple levels of biochemistry may be useful in treating proteinuric kidney disease.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for adults with early (stage 1 to 3) non-diabetic chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a long term condition that occurs as a result of damage to the kidneys. Early recognition of CKD is becoming increasingly common due to widespread laboratory estimated glomerular filtration rate (eGFR) reporting, raised clinical awareness, and international adoption of Kidney Disease Outcomes Quality Initiative (K/DOQI) classification. Early recognition and management of CKD affords the opportunity not only to prepare for progressive kidney impairment and impending renal replacement therapy, but also for intervening to reduce the risk of progression and cardiovascular disease. Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB) are two classes of antihypertensive drugs that act on the renin-angiotensin-aldosterone system. Beneficial effects of ACEi and ARB on renal outcomes and survival in people with a wide range of severity of renal impairment have been reported; however, their effectiveness in the subgroup of people with early CKD (stage 1 to 3) is less certain.

OBJECTIVES

This review aimed to evaluate the benefits and harms of ACEi and ARB or both in the management of people with early (stage 1 to 3) CKD who do not have diabetes mellitus.

SEARCH STRATEGY

In March 2010 we searched The Cochrane Library, including The Cochrane Renal Group's specialised register and The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Reference lists of review articles and relevant studies were also checked. The search was conducted using the optimally sensitive strategy developed by the Cochrane Collaboration for the identification of randomised controlled trials (RCTs) with input from an expert in trial search strategy.

SELECTION CRITERIA

All RCTs reporting the effect of ACEi or ARB in people with early (stage 1 to 3) CKD who did not have diabetes mellitus were selected for inclusion. Only studies of at least four weeks duration were selected. Authors, working in teams of two, independently assessed the retrieved titles and abstracts, and whenever necessary the full text of these studies were screened to determine which studies satisfied the inclusion criteria.

DATA COLLECTION AND ANALYSIS

Data extraction was carried out by two authors, independently, using a standard data extraction form and cross checked by two other authors. Methodological quality of included studies was assessed using the Cochrane risk of bias tool. Data entry was carried out by one author and cross checked by another author. When more than one study reported similar outcomes, data were pooled using the random-effects model, but a fixed-effect model was also analysed to ensure the robustness of the model chosen and to check susceptibility to outliers. Heterogeneity was analysed using a Chi² test on N-1 degrees of freedom, with an alpha of 0.05 used for statistical significance and with the I² test. Where data permitted, subgroup analysis was used to explore possible sources of heterogeneity. The quality of the evidence was analysed.

MAIN RESULTS

Four RCTs enrolling 2177 participants met our inclusion criteria. Of these, three compared ACEi with placebo and one compared ACEi with ARB. Two studies had an overall low risk of bias, and the other two were considered to be at moderate to high risk of bias. Low to moderate quality of evidence (from two studies representing 1906 patients) suggested that ACEi had no impact on all-cause mortality (RR 1.80, 95% CI 0.17 to 19.27, P = 0.63) or cardiovascular events (RR 0.87, 95% CI 0.66 to 1.14, P = 0.31) in people with stage 3 CKD. For all-cause mortality, there was substantial heterogeneity in the results. One study (quality assessment: low risk of bias) reported no difference in the risk of end-stage kidney disease in those with an eGFR > 45 mL/min/1.74 m² treated with ACEi versus placebo (RR 1.00, 95% CI 0.09 to 1.11, P = 0.99). The (high risk of bias) study that compared ACEi with ARB reported little difference in effect between the treatments when urinary protein, blood pressure or creatinine clearance were compared. No published studies comparing ARB with placebo or ACEi and ARB with placebo were identified.

AUTHORS' CONCLUSIONS

Our review demonstrated that there is currently insufficient evidence to determine the effectiveness of ACEi or ARB in patients with stage 1 to 3 CKD who do not have diabetes mellitus. We have identified an area of significant uncertainty for a group of patients who account for most of those labelled as having CKD.

Antihypertensive medication use and change in kidney function in elderly adults: a marginal structural model analysis

BACKGROUND

The evidence for the effectiveness of antihypertensive medication use for slowing decline in kidney function in older persons is sparse. We addressed this research question by the application of novel methods in a marginal structural model.

METHODS

Change in kidney function was measured by two or more measures of cystatin C in 1,576 hypertensive participants in the Cardiovascular Health Study over 7 years of follow-up (1989-1997 in four U.S. communities). The exposure of interest was antihypertensive medication use. We used a novel estimator in a marginal structural model to account for bias due to confounding and informative censoring.

RESULTS

The mean annual decline in eGFR was 2.41 ± 4.91 mL/min/1.73 m(2). In unadjusted analysis, antihypertensive medication use was not associated with annual change in kidney function. Traditional multivariable regression did not substantially change these estimates. Based on a marginal structural analysis, persons on antihypertensives had slower declines in kidney function; participants had an estimated 0.88 (0.13, 1.63) ml/min/1.73 m(2) per year slower decline in eGFR compared with persons on no treatment. In a model that also accounted for bias due to informative censoring, the estimate for the treatment effect was 2.23 (-0.13, 4.59) ml/min/1.73 m(2) per year slower decline in eGFR.

CONCLUSION

In summary, estimates from a marginal structural model suggested that antihypertensive therapy was associated with preserved kidney function in hypertensive elderly adults. Confirmatory studies may provide power to determine the strength and validity of the findings.

Are there pleiotropic effects of antihypertensive medications or is it all about the blood pressure in the patient with diabetes and hypertension?

Many small studies with varied surrogate end points and numerous preclinical data have suggested the likelihood of there being specific benefits that exceed simple blood pressure control with drug classes such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and calcium channel blockers, which may be particularly relevant to the patient with diabetes and hypertension. Large clinical trials, however, have provided only token support for this idea. Likewise, meta-analyses that have incorporated varied clinical trials, albeit with somewhat heterogeneous data, have not been particularly forthcoming in their support of this concept. In the patient with diabetes and hypertension, tight blood pressure control, more so than using a specific drug class, is the most important aspect of therapy.

Development and validation of a self-assessment tool for albuminuria: results from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND

The prevalence of albuminuria in the general population is high, but awareness of it is low. Therefore, we sought to develop and validate a self-assessment tool that allows individuals to estimate their probability of having albuminuria.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

The population-based Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study for model development and the National Health and Nutrition Examination Survey (NHANES) 1999-2004 for model validation. US adults 45 years or older in the REGARDS Study (n = 19,697) and NHANES 1999-2004 (n = 7,168).

PREDICTOR

Candidate items for the self-assessment tool were collected using a combination of interviewer- and self-administered questionnaires.

OUTCOME

Albuminuria was defined as a urinary albumin to urinary creatinine ratio ≥30 mg/g in spot samples.

RESULTS

8 items were included in the self-assessment tool (age, race, sex, current smoking, self-rated health, and self-reported history of diabetes, hypertension, and stroke). These items provided a C statistic of 0.709 (95% CI, 0.699-0.720) and good model fit (Hosmer-Lemeshow χ(2)P = 0.49). In the external validation data set, the C statistic for discriminating individuals with and without albuminuria using the self-assessment tool was 0.714. Using a threshold of ≥10% probability of albuminuria from the self-assessment tool, 36% of US adults 45 years or older in NHANES 1999-2004 would test positive and be recommended for screening. Sensitivity, specificity, and positive and negative predictive values for albuminuria associated with a probability ≥10% were 66%, 68%, 23%, and 93%, respectively.

LIMITATIONS

Repeated urine samples were not available to assess the persistency of albuminuria.

CONCLUSIONS

8 self-report items provide good discrimination for the probability of having albuminuria. This tool may encourage individuals with a high probability to request albuminuria screening.

Progression of renal dysfunction in patients with cardiovascular disease

It has been established that patients with chronic kidney disease (CKD) suffer from frequent cardiovascular events. On the other hand, recent studies suggest that renal damage tends to worsen in patients with cardiovascular diseases (CVD). Although the mechanisms for the cardiorenal association are unclear, the presence of arteriosclerotic risk factors common to both CVD and CKD is important. In arteriosclerosis, vascular derangement progresses not only in the heart but also in the kidney. In addition, heart failure, cardiac catheterization and hesitation of medical treatments due to renal dysfunction may explain the progression of renal damage. Therefore, the goal of treatments is a total control of arteriosclerotic risk factors. Medication should be selected among agents with protective effects on both heart and kidney. It is important to always consider the presence of CKD for the treatment of the cardiovascular disease and strictly control the risk factors.

Proteinuria in special populations: pregnant women and children

Proteinuria is the hallmark of glomerular kidney disease. It is used diagnostically to follow disease progression and to determine response to therapy. Thus, it is necessary to have an understanding of the mechanisms of proteinuria and the limitations to its accurate assessment in special populations. In this article, we review 2 special populations--pregnant women and children--providing insight into their unique circumstances that require consideration when assessing proteinuria.

Clinical outcome of renal tubular damage in chronic heart failure

AIMS

Both reduced glomerular filtration and increased urinary albumin excretion independently determine outcome in patients with chronic heart failure (HF). However, tubulo-interstitial injury might indicate renal damage, even in the presence of normal glomerular filtration. We studied the relationship between tubular damage, glomerular filtration, urinary albumin excretion, and outcome in HF patients.

METHODS AND RESULTS

In 2130 patients participating in the GISSI-HF trial, we measured urinary albumin-to-creatinine ratio (UACR), estimated glomerular filtration rate (eGFR), and three urinary markers of tubular damage: N-acetyl-beta-D-glucosaminidase (NAG), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). We assessed the relationship between the individual tubular damage markers and the combined endpoint of all-cause mortality and HF hospitalizations. Mean age was 67 ± 11 years, and 21% were female. Urinary NAG 13.7 (7.8-22) U/gCr, KIM-1 1939 (671-3871) ng/gCr, and NGAL 36 (14-94) µg/gCr were markedly elevated above normal levels. All individual tubular markers were independently associated with the combined endpoint: NAG: adjusted hazard ratio (HR) 1.22; 95% confidence interval (CI), 1.10-1.36; P< 0.001, KIM-1 HR 1.13; 95% CI, 1.02-1.24; P= 0.018 and NGAL HR 1.10; 95% CI, 1.00-1.20; P= 0.042; all per log standard deviation increase). Even in patients with a normal eGFR, increased tubular markers were related to a poorer outcome. The combination of impaired eGFR, increased UACR, and high NAG was associated with a HR of 3.00; 95% CI, 2.29-3.95; P< 0.001, compared with those without these abnormalities.

CONCLUSION

Tubular damage is related to a poor clinical outcome in HF patients even when eGFR is normal.

Systolic pressure, diastolic pressure, or pulse pressure as a cardiovascular risk factor in renal disease

Chronic kidney disease is a leading global health problem with an increasing prevalence. Hypertension is present in most patients with chronic kidney disease, and hypertension-related nephrosclerosis is a top cause of progressive renal damage and end-stage renal disease. Systolic blood pressure (BP) and pulse pressure, together with nocturnal BP, are the most important factors favoring the progression of renal failure. Consequently, strict control of BP and other cardiovascular risk factors is required, including an adequate degree of suppression of the renin-angiotensin system in every patient.

Beneficial effect of aliskiren combined with olmesartan in reducing urinary protein excretion in patients with chronic kidney disease

BACKGROUND

Blockade of the renin-angiotensin-aldosterone system is a therapeutic mainstay in patients with chronic kidney disease (CKD). However, the renoprotective effect of the novel direct renin inhibitor aliskiren is unknown.

MATERIALS AND METHODS

We performed a prospective study in 10 CKD patients. All 10 patients with persistent proteinuria (urinary protein-to-creatinin ratio 0.3-3.5 g/g), despite good blood pressure control (<130/80 mmHg) with olmesartan, were started on 150 mg/day aliskiren. Clinical parameters were examined before and after 4, 8, 12, and 16 weeks of treatment.

RESULTS

Urinary protein-to-creatinine ratio significantly decreased by about 40% at 16 weeks from baseline (P = 0.0002), although estimated glomerular filtration rate and blood pressure did not change throughout the study period. Plasma renin activity also decreased significantly from baseline (P = 0.019), although plasma aldosterone concentration did not change.

CONCLUSIONS

Aliskiren combined with olmesartan reduces proteinuria in CKD patients.

Common secondary causes of resistant hypertension and rational for treatment

Resistant hypertension is defined as uncontrolled blood pressure despite the use of three antihypertensive drugs, including a diuretic, in optimal doses. Treatment resistance can be attributed to poor adherence to antihypertensive drugs, excessive salt intake, physician inertia, inappropriate or inadequate medication, and secondary hypertension. Drug-induced hypertension, obstructive sleep apnoea, primary aldosteronism, and chronic kidney disease represent the most common secondary causes of resistant hypertension. Several drugs can induce or exacerbate pre-existing hypertension, with non-steroidal anti-inflammatory drugs being the most common due to their wide use. Obstructive sleep apnoea and primary aldosteronism are frequently encountered in patients with resistant hypertension and require expert management. Hypertension is commonly found in patients with chronic kidney disease and is frequently resistant to treatment, while the management of renovascular hypertension remains controversial. A step-by-step approach of patients with resistant hypertension is proposed at the end of this review paper.

Imagine how many lives you save: angiotensin-converting enzyme inhibition for atherosclerotic vascular disease in the present era of risk reduction

INTRODUCTION

Angiotensin-converting enzyme (ACE) inhibition is clearly beneficial in patients with hypertension, heart failure, and post-myocardial infarction left ventricular (LV) dysfunction. However, whereas initial trials had reported a benefit of ACE inhibition in high-risk vascular patients, current trials of ACE inhibition have failed to demonstrate a clear benefit in vascular patients who are receiving risk-reduction interventions. The purpose of this review is to analyze the reasons behind the failure of the most recent trials of ACE inhibitors in vascular patients without overt LV dysfunction. The reader will gain an understanding of the time-dependent trend towards a reduction in the absolute benefit conferred by ACE inhibition in patients with vascular atherosclerosis as risk reduction interventions are increasingly implemented.

AREAS COVERED

Major trials with a follow-up period of at least 1 year assessing the use of ACE inhibitors in patients with a history of cardiac or vascular events were identified via a PubMed literature search. All-cause and cardiovascular mortality outcomes were reported for each trial, as well as the use of aspirin, lipid-lowering drugs and β-blockers, and the mean LV ejection fraction.

EXPERT OPINION

The findings of recent trials do not support the use of ACE inhibitors in vascular patients who, adherent with risk reduction therapy, do not have hypertension, diabetes, or LV dysfunction.

Metabolic syndrome, chronic kidney disease, and cardiovascular disease: a dynamic and life-threatening triad

The metabolic syndrome (MS) and chronic kidney disease (CKD) have both become global public health problems, with increasing social and economic impact due to their high prevalence and remarkable impact on morbidity and mortality. The causality between MS and CKD, and its clinical implications, still does remain not completely understood. Moreover, prophylactic and therapeutic interventions do need to be properly investigated in this field. Herein, we critically review the existing clinical evidence that associates MS with renal disease and cardiovascular disease, as well as the associated pathophysiologic mechanisms and actual treatment options.

Effect of RAAS inhibition on the incidence of cancer and cancer mortality in patients with glomerulonephritis

Angiotensin II type 1 receptor blocker (ARB), which is frequently prescribed in patients with glomerulonephritis (GN), is suggested to increase the risk of cancer. We registered 3,288 patients with renal biopsy and analyzed the relationship between the use of renin-angiotensin-aldosterone system (RAAS) blockade and the incidence of cancer or cancer mortality. After renal biopsy, cancer developed in 33 patients with an incidence rate of 1.0% (95% of CI for incidence: 0.7%-1.3%). There was no difference in the cancer incidence among the groups according to the use of angiotensin-converting enzyme inhibitors (ACEI) or ARB: 1.2% in the None (23/1960), 0.7% in the ARB-only (5/748), 0.4% in the ACEI-only (1/247), and 1.2% in the ACEI-ARB (4/333) (P = 0.487) groups. The cancer mortality was 2.1%, 0.4%, 0.0%, and 0.3% in None, ACEI-only, ARB-only, and ACEI-ARB group, respectively (P < 0.001). The risk of cancer mortality in patients with ARB was only 0.124 (0.034-0.445) compared to that of non-users of ARB by Cox's hazard proportional analysis. In conclusion, prescription of ACEI or ARB in patients with GN does not increase cancer incidence and recipients of ARB show rather lower rates of all-cause mortality and cancer mortality.

Role of angiotensin II in the development of nephropathy and podocytopathy of diabetes

Diabetic kidney disease is the leading cause of end-stage renal disease worldwide. Podocytes are highly differentiated, pericyte-like cells that are essential for normal function of the kidney filter. Loss of podocytes is a hallmark of progressive kidney diseases including diabetic nephropathy. Podocytes are a direct target for angiotensin II - mediated injury by altered expression and distribution of podocyte proteins. Additionally, angiotensin II promotes podocyte injury indirectly by increasing calcium influx and production of reactive oxygen species. Notwithstanding the convincing rationale for angiotensin II blockade as a treatment modality, the incidence of diabetes-related end stage renal disease has increased steadily despite widespread use of angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs). Recently published clinical trials have rekindled a debate on the safety and efficacy of dual blockade of the renin-angiotensin system (RAS). This review summarizes the rationale for blockade of angiotensin II as a therapeutic target in treating diabetic kidney disease, including the critical role played by podocytes. Recent relevant clinical trials on the role of RAS blockade in the treatment of diabetic kidney disease are discussed.

Protein microarrays discover angiotensinogen and PRKRIP1 as novel targets for autoantibodies in chronic renal disease

Biomarkers for early detection of chronic kidney disease are needed, as millions of patients suffer from chronic diseases predisposing them to kidney failure. Protein microarrays may also hold utility in the discovery of auto-antibodies in other conditions not commonly considered auto-immune diseases. We hypothesized that proteins are released as a consequence of damage at a cellular level during end-organ damage from renal injury, not otherwise recognized as self-antigens, and an adaptive humoral immune response to these proteins might be detected in the blood, as a noninvasive tracker of this injury. The resultant antibodies (Ab) detected in the blood would serve as effective biomarkers for occult renal injury, enabling earlier clinical detection of chronic kidney disease than currently possible, because of the redundancy of the serum creatinine as a biomarker for early kidney injury. To screen for novel autoantibodies in chronic kidney disease, 24 protein microarrays were used to compare serum Ab from patients with chronic kidney disease against matched controls. From a panel of 38 antigens with increased Ab binding, four were validated in 71 individuals, with (n=50) and without (n=21) renal insufficiency. Significant elevations in the titer of novel auto-Ab were noted against angiotensinogen and PRKRIP1 in renal insufficiency. Current validation is underway to evaluate if these auto-Ab can provide means to follow the evolution of chronic kidney disease in patients with early stages of renal insufficiency, and if these rising titers of these auto-Ab correlate with the rate of progression of chronic kidney disease.

Atherosclerotic renovascular disease and the heart

The detrimental link between cardiac and renal pathophysiology in atherosclerotic renovascular disease (ARVD) is well described. Patients with ARVD usually have significant atherosclerotic disease in other vascular beds including the coronary circulation, and structural and functional cardiac changes are highly prevalent. This excess cardiovascular burden probably contributes to the increased cardiac morbidity and mortality seen in these patients. In this review we describe the associations of cardiovascular disease and ARVD and treatment thereof. The clinical debate of which patients are offered any additional advantage by revascularisation over medications alone remains to be answered. The close link between cardiac and renal pathophysiology in ARVD raises the possibility that renal revascularisation might confer a benefit to cardiac morphology and function. This is the subject of ongoing randomised controlled trials.

The importance of renin-angiotensin blockade in patients with cardio-renal disease

The existence of the renin-angiotensin-aldosterone system was first postulated over 100 years ago. Following the identification of all the major components, came the discovery of their potential pathogenicity in cardiovascular and renal disease. The introduction of drugs that inhibit the synthesis or actions of this system has prompted a number of trials that have largely shaped how cardiovascular and renal disease is managed today. The continued discovery of yet more components of this system promises to further our understanding of its influence on disease processes and herald the development of more highly selective drugs, ensuring that the renin-angiotensin-aldosterone system will continue to be a key area of interest for many years to come.

Doubling of serum creatinine: is it appropriate as the endpoint for CKD? Proposal of a new surrogate endpoint based on the reciprocal of serum creatinine

BACKGROUND

The evaluation of the progression of renal insufficiency, or decline in glomerular filtration rate (GFR), has been approached more simply and precisely by converting measured serum creatinine value into the reciprocal of serum creatinine, estimated GFR, or other parameters. Doubling of serum creatinine (simple doubling) is conveniently used as a surrogate endpoint for progression of renal disease but is thought to be biased unfairly by the initial value of serum creatinine (Scr(Int)). We proposed the definite decline in the reciprocal of serum creatinine (2-4 doubling) as a surrogate endpoint, comparing simple doubling with this new endpoint to verify the effect of Scr(Int) on the endpoint.

METHODS

For the purpose of comparison between endpoints, 194 patients in a historical cohort of chronic glomerulonephritis were investigated. Kaplan-Meier survival analysis was performed with the composite endpoint of need for dialysis and either simple doubling or 2-4 doubling. Then, the distribution of Scr(Int) was compared between total patients and patients developing each endpoint.

RESULTS

The endpoint value of serum creatinine (Scr(End)) with 2-4 doubling was lower than that with simple doubling at Scr(Int) <2.00 mg/dl, and the difference of Scr(End) between simple doubling and 2-4 doubling was larger, as Scr(Int) became lower. In patients reaching simple doubling, Scr(Int) was higher than that of the total patients (1.66 vs. 1.07 mg/dl in median, respectively; p < 0.001). In patients reaching 2-4 doubling, there was no significant difference in Scr(Int).

CONCLUSION

Patients with low serum creatinine concentration at baseline had a tendency of prolonged development into simple doubling. In contrast, with 2-4 doubling, there was no bias of Scr(Int).

Regression of superficial glomerular podocyte injury in type 2 diabetic rats with overt albuminuria: effect of angiotensin II blockade

OBJECTIVE

Clinical studies indicate that the remission, regression or both of nephrotic-range albuminuria are exerted by angiotensin II receptor blockers (ARBs) in diabetes. The current study was performed to test the hypothesis that these effects of ARBs are associated with regression of glomerular podocyte injury.

METHODS

We examined the effects of an ARB, olmesartan, on glomerular podocyte injury in type 2 diabetic Otsuka-Long-Evans-Tokushima-Fatty rats with overt albuminuria.

RESULTS

At baseline (55-week-old), diabetic Otsuka-Long-Evans-Tokushima-Fatty rats showed severe albuminuria with desmin-positive areas (an index of podocyte injury) in both superficial and juxtamedullary glomeruli, and podocyte injury was much greater in juxtamedullary than in superficial glomeruli. At 75-week-old, Otsuka-Long-Evans-Tokushima-Fatty rats had developed more severe albuminuria and superficial glomerular podocyte injury, whereas juxtamedullary glomerular podocyte injury did not advance further. Olmesartan (10 mg/kg per day) decreased albuminuria and superficial glomerular desmin staining to levels that were lower than those at baseline, whereas advanced juxtamedullary glomerular podocyte injury was not changed.

CONCLUSION

The current study demonstrates for the first time that juxtamedullary glomerular podocyte injury reaches a severe condition at an earlier time than superficial glomerular podocyte injury during the progression of overt albuminuria in type 2 diabetic rats. Our data also support the hypothesis that the antialbuminuric effects of ARBs are associated with regression of superficial glomerular podocyte injury in type 2 diabetes with nephrotic-range albuminuria.

When to initiate ACEI/ARB therapy in patients with type 1 and 2 diabetes

Angiotensin converting enzyme inhibitors (ACEI) and angiotensin 2 receptor blockers (ARB) have become a mainstay of adjunctive therapy for the prevention and amelioration of diabetic nephropathy. Although ACEI were shown over 20 years ago to slow the rate of loss of renal function in diabetic subjects with decreased renal function, the question of how early in the course of diabetes to introduce them remains unresolved. Recent studies suggest that very early initiation of ACEI/ARB therapy may not have demonstrable beneficial effects even over a period of years.