initial angiotensin receptor blockade-induced decrease in albuminuria is associated with long-term renal outcome in type 2 diabetic patients with microalbuminuria: a post hoc analysis of the IRMA-2 trial

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Progression and regression of kidney disease in type 1 diabetes

Diabetic kidney disease is distinguished by the presence of albuminuria, hypertension, declining kidney function, and a markedly elevated cardiovascular disease risk. This constellation of clinical features drives the premature mortality associated with type 1 diabetes. The first epidemiological investigations concerning type 1 diabetes-related albuminuria date back to the 1980s. The early studies found that proteinuria - largely equivalent to severe albuminuria - developed in 35 to 45% of individuals with type 1 diabetes, with the diabetes duration-specific incidence rate pattern portraying one or two peaks. Furthermore, moderate albuminuria, the first detectable sign of diabetic kidney disease, was found to nearly inexorably progress to overt kidney disease within a short span of time. Since the early reports, studies presenting more updated incidence rates have appeared, although significant limitations such as study populations that lack broad generalizability, study designs vulnerable to substantive selection bias, and constrained follow-up times have been encountered by many. Nevertheless, the most recent reports estimate that in modern times, moderate - instead of severe - albuminuria develops in one-third of individuals with type 1 diabetes; yet, a considerable part (up to 40% during the first ten years after the initial albuminuria diagnosis) progresses to more advanced stages of the disease over time. An alternative pathway to albuminuria progression is its regression, which affects up to 60% of the individuals, but notably, the relapse rate to a more advanced disease stage is high. Whether albuminuria regression translates into a decline in cardiovascular disease and premature mortality risk is an area of debate, warranting more detailed research in the future. Another unclear but alarming feature is that although the incidence of severe albuminuria has fallen since the 1930s, the decline seems to have reached a plateau after the 1980s. This stagnation may be due to the lack of kidney-protective medicines since the early 1980s, as the recent breakthroughs in type 2 diabetes have not been applicable to type 1 diabetes. Therefore, novel treatment strategies are at high priority within this patient population.

Optimization of Albuminuria-Lowering Treatment in Diabetes by Crossover Rotation to Four Different Drug Classes: A Randomized Crossover Trial

OBJECTIVE

Renin-angiotensin system (RAS) inhibitors decrease the urinary albumin to creatinine ratio (UACR) but are ineffective in up to 40% of patients. We hypothesized that rotation through different drug classes overcomes RAS inhibitor resistance and tested this in a randomized crossover trial.

RESEARCH DESIGN AND METHODS

We assigned 26 adults with type 1 diabetes and 37 with type 2 diabetes and UACR between 30 and 500 mg/g and estimated glomerular filtration rate >45 mL/min/1.73 m2 to 4-week treatment periods with telmisartan 80 mg, empagliflozin 10 mg, linagliptin 5 mg, and baricitinib 2 mg in random order, separated by 4-week washout periods. Each participant was then re-exposed for 4 weeks to the drug that induced that individual's largest UACR reduction. Primary outcome was the difference in UACR response to the best-performing drug during the confirmation period versus UACR response to the other three drugs.

RESULTS

There was substantial variation in the best-performing drug. Telmisartan was best performing for 33 participants (52%), empagliflozin and linagliptin in 11 (17%), and baricitinib in 8 participants (13%). The individuals' best-performing drug changed UACR from baseline during the first and confirmatory exposures by a mean of -39.6% (95% CI -44.8, -33.8; P < 0.001) and -22.4% (95% CI -29.7, -12.5; P < 0.001), respectively. The Pearson correlation for first versus confirmatory exposure was 0.39 (P = 0.017). The mean change in UACR with the other three drugs was +1.6% (95% CI -4.3%, 8.0%; P = 0.593 versus baseline; difference versus individuals' best-performing drug at confirmation, 30.9% [95% CI 18.0, 45.3]; P < 0.001).

CONCLUSIONS

We demonstrated a large and reproducible variation in participants' responses to different UACR-lowering drug classes. These data support systematic rotation through different drug classes to overcome therapy resistance to RAS inhibition.

Recent therapeutic targets in diabetic nephropathy

BACKGROUND

The prevalence of diabetes mellitus has been increased dramatically which in turn leads to complications including cardiovascular diseases, diabetic kidney disease, and substantially end-stage renal disease.

METHODS

We reviewed articles discussing the pathophysiology of diabetic nephropathy with new agents that may be useful in the management of the disease. We used PubMed, Scopus, Google Scholar and the Open-access searching engines.

RESULTS

The recent recommendations primarily depend on glycaemic and blood pressure control and the use of standard renin-angiotensin system blockade. Currently, the use of agents with nephroprotective effects beyond the hyperglycaemic lowering effect has been evidenced clinically.

CONCLUSIONS

In his review, the pathophysiology, clinical manifestations, and lines of treatment of diabetic nephropathy are discussed. In addition, a focus on the clinical role and nephroprotective effects of the emerging therapeutic class, dipeptidyl peptidase IV (DPP-4) inhibitors, is addressed in detail.

Effects of Linagliptin on Cardiovascular and Kidney Outcomes in People With Normal and Reduced Kidney Function: Secondary Analysis of the CARMELINA Randomized Trial

OBJECTIVE

Type 2 diabetes is a leading cause of kidney failure, but few outcome trials proactively enrolled individuals with chronic kidney disease (CKD). We performed secondary analyses of cardiovascular (CV) and kidney outcomes across baseline estimated glomerular filtration rate (eGFR) categories (≥60, 45 to <60, 30 to <45, and <30 mL/min/1.73 m2) in Cardiovascular and Renal Microvascular Outcome Study With Linagliptin (CARMELINA), a cardiorenal placebo-controlled outcome trial of the dipeptidyl peptidase 4 inhibitor linagliptin (NCT01897532).

RESEARCH DESIGN AND METHODS

Participants with CV disease and/or CKD were included. The primary outcome was time to first occurrence of CV death, nonfatal myocardial infarction, or nonfatal stroke (three-point major adverse CV event [3P-MACE]), with a secondary outcome of renal death, end-stage kidney disease, or sustained ≥40% decrease in eGFR from baseline. Other end points included progression of albuminuria, change in HbA1c, and adverse events (AEs) including hypoglycemia.

RESULTS

A total of 6,979 subjects (mean age 65.9 years; eGFR 54.6 mL/min/1.73 m2; 80.1% albuminuria) were followed for 2.2 years. Across eGFR categories, linagliptin as compared with placebo did not affect the risk for 3P-MACE (hazard ratio 1.02 [95% CI 0.89, 1.17]) or the secondary kidney outcome (1.04 [0.89, 1.22]) (interaction P values >0.05). Regardless of eGFR, albuminuria progression was reduced with linagliptin, as was HbA1c, without increasing risk for hypoglycemia. AEs were balanced among groups overall and across eGFR categories.

CONCLUSIONS

Across all GFR categories, in participants with type 2 diabetes and CKD and/or CV disease, there was no difference in risk for linagliptin versus placebo on CV and kidney events. Significant reductions in risk for albuminuria progression and HbA1c and no difference in AEs were observed.

High ACR level is a strong risk factor for renal tubular impairment in patients with type 2 diabetes: A longitudinal observational study

BACKGROUND

Several studies have indicated that high albuminuria is associated with renal function decline. However, the relationship between the urinary albumin-to-creatinine ratio (ACR) and risk of developing tubular injury remains unclear. Our aim was to investigate the association of ACR with the risk of developing tubular impairment in patients with type 2 diabetes.

METHODS

This longitudinal observational study compared baseline with follow-up data in 183 patients with type 2 diabetes. ACR, urinary alpha-1-microglobulin-to-creatinine ratio (A1MCR) and estimated glomerular filtration rate (eGFR) were used to evaluate albuminuira, tubular injury and glomerular filtration function, respectively.

RESULTS

Levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and A1MCR were significantly different at the two-year follow-up compared with baseline levels. Among patients both with baseline ACR above and below 30 mg/g, the percentage with A1MCR > 15 mg/g clearly increased after follow-up (P < 0.05). The risk of A1MCR rising from normal ranges to >15 mg/g over the follow-up increased with increasing baseline ACR values lower baseline eGFR. Among the patients with baseline ACR > 63.10 mg/g, all showed increased A1MCR values at follow-up compared with baseline. In the multivariate regression analysis, the patients with baseline ACR > 63.10 mg/g had a strong risk of A1MCR rising from normal to >15 mg/g (odds ratio (OR) = 11.12, P = 0.001) over the follow-up, while the males had a 2.89-fold risk of A1MCR increasing from normal to >15 mg/g compared with females.

CONCLUSION

Baseline ACR level is related to increased risk of developing renal tubular injury; in particular, this association is much stronger in patients with type 2 diabetes and baseline ACR > 63.10 mg/g.

The short-term effects of angiotensin II receptor blockers on albuminuria and renal function in Korean patients

Each angiotensin II receptor blocker (ARB) asserts independent molecular effects. No study has compared the renoprotective potency of different types of ARBs in Korea. This study evaluated the differences among medications for treating albuminuria. Data were obtained from electronic medical records of adult patients who underwent albuminuria test and received treatment with either angiotensin-converting enzyme inhibitors (ACEIs) or ARBs between January 2009 and June 2016. Patients' albuminuria and renal function data were observed for three months after treatment initiation. In total, 1475 patients were included. Patients treated with ACEIs had no significant changes in albuminuria (from 127.7 ± 55.1 mg/g to 46.7 ± 18.7 mg/g, P = .127), but those treated with ARBs showed significant improvement (from 491.2 ± 33.2 mg/g to 372.0 ± 28.0 mg/g, P < .001). The ARB group had significantly more patients with normal albuminuria after treatment (from 55.8% to 59.3% for normal albuminuria, from 16.7% to 18.5% for moderately increased albuminuria and from 27.5% to 22.2% for severely increased albuminuria, P = .005), but renal function did not change significantly. Subgroup analysis of ARB types showed that candesartan (from 712.5 ± 71.1 to 489.8 ± 57.8 mg/g, P < .001) and irbesartan (from 522.6 ± 65.7 to 352.6 ± 54.3 mg/g, P < .001) had significant effects. Candesartan improved albuminuria in patients older than 60 years (from 506.9 ± 84.2 to 371.9 ± 70.6 mg/g, P = .004) and irbesartan improved albuminuria in patients with glomerular filtration rate <60 (from 551.6 ± 100.0 to 392.4 ± 76.2, P = .007). Only irbesartan and candesartan could reduce albuminuria, suggesting that all ARBs do not have the same outcome. This indicates the importance of optimizing ARB selection, considering both patient condition and organ-specific characteristics of medications.

Predicting albuminuria response to spironolactone treatment with urinary proteomics in patients with type 2 diabetes and hypertension

Background

The mineralocorticoid receptor antagonist spironolactone significantly reduces albuminuria in patients with diabetes. Prior studies have shown large between-patient variability in albuminuria treatment response. We previously developed and validated a urinary proteomic classifier that predicts onset and progression of chronic kidney disease. Here, we tested whether the proteomic classifier based on 273 urinary peptides (CKD273) predicts albuminuria response to spironolactone treatment.

Methods

We performed a post hoc analysis in a double-blind randomized clinical trial with allocation to either spironolactone 12.5-50 mg/day (n = 57) or placebo (n = 54) for 16 weeks. Patients were diagnosed with type 2 diabetes and resistant hypertension. Treatment was an adjunct to renin-angiotensin system inhibition. Primary endpoint was the percentage change in urine albumin to creatinine ratio (UACR). Capillary electrophoresis mass spectrometry was used to quantify urinary peptides at baseline. The previously validated combination of 273 known urinary peptides was used as proteomic classifier.

Results

Spironolactone reduced UACR relative to placebo by 50%, although with a large between-patient variability in UACR response (5th to 95th percentile, 7 to 312%). An interaction was detected between CKD273 and treatment assignment (β = -1.09, P = 0.026). Higher values of CKD273 at baseline were associated with a larger reduction in UACR in the spironolactone group (β = -0.70, P = 0.049), but not in the placebo group (β = 0.39, P = 0.25). Stratified in tertiles of baseline CKD273, reduction in UACR was greater in the highest tertile, 63% (95% confidence interval: 35-79%), as compared with the two other tertiles combined, 16% (-17 to 40%) (P = 0.011).

Conclusions

A urinary proteomics classifier can be used to identify individuals with type 2 diabetes who are more likely to show an albuminuria-lowering response to spironolactone treatment. These results suggest that urinary proteomics may be a valuable tool to tailor therapy, but confirmation in a larger clinical trial is required.

Multimarker Panels in Diabetic Kidney Disease: The Way to Improved Clinical Trial Design and Clinical Practice?

Diabetic kidney disease (DKD) is a complex and multifactorial disorder associated with deregulations in a large number of different biological pathways on the molecular level. Using the 2 established biomarkers, estimated glomerular filtration rate (eGFR) and albuminuria will not allow allocating patients to tailored therapy. Molecular multimarker panels as sensors for the deregulation of the various disease mechanisms combined with a better understanding of how investigational as well as approved drugs interfere with these disease processes forms the basis for platform trials in DKD. In these platform trials, patients with DKD are assigned to the most suitable treatment arm based on their molecular marker profile. Close monitoring of biomarkers after treatment initiation together with assessment of renal function and "off-target" effects will allow identification of therapy responders, with nonresponders shifted to the next-best treatment arm based on their molecular profile. In this viewpoint article, we summarize evidence on the variation of DKD disease progression as well as the response to therapy and outline procedures to model disease pathophysiology supporting biomarker panel construction. Finally, the use of biomarkers in clinical trial setup is discussed.

N-terminal pro-brain natriuretic peptide (NT-proBNP) predicts the cardio-renal response to aliskiren in patients with type 2 diabetes at high renal and cardiovascular risk

Sodium retention and volume overload are the main determinants of poor response to renin-angiotensin-aldosterone system (RAAS) inhibition in patients with diabetes. As volume excess can exist without symptoms, biomarkers are needed to identify a priori which patients are volume overloaded and may experience less benefit from RAAS inhibition. N-terminal pro-brain natriuretic peptide (NT-proBNP) is released in the setting of increased cardiac wall stress and volume overload. We conducted a post hoc analysis among 5081 patients with type 2 diabetes mellitus participating in the ALTITUDE trial to investigate whether NTproBNP can predict the effects of additional therapy with aliskiren on cardio-renal endpoints. Aliskiren compared to placebo reduced the risk of the primary cardio-renal endpoint events by 20% (95% confidence interval [CI] 16 to 61) and 2% (95% CI -42 to 30) in the two lowest NT-proBNP tertiles, and it increased the risk by 25% (95% CI -4 to 96) in the highest NT-proBNP tertile (P value for trend = 0.009). Similar trends were observed for the cardiovascular and end-stage renal disease endpoints. Effects of aliskiren compared to placebo on safety outcomes (hyperkalaemia and hospitalization for acute kidney injury) were independent of NT-proBNP. In conclusion, baseline NT-proBNP may be used as a marker to predict the response to aliskiren with regard to cardio-renal outcomes when added to standard therapy with RAAS inhibition.

Mild Albuminuria Is a Risk Factor for Faster GFR Decline in the Nondiabetic Population

INTRODUCTION

A minimal increase in the albumin-to-creatinine ratio (ACR) predicts cardiovascular disease and mortality, but whether it predicts kidney function loss in nondiabetic persons is unclear. We investigated the association between ACR in the optimal or high-normal range and the rate of glomerular filtration rate (GFR) decline in a cohort from the general population without diabetes, cardiovascular, or chronic kidney disease.

METHODS

In the Renal Iohexol Clearance Survey, we measured GFR using iohexol clearance in 1567 middle-aged nondiabetic individuals with an ACR <3.40 mg/mmol (30.0 mg/g) at baseline. The ACR was measured in unfrozen morning urine samples collected on 3 days before the GFR measurements. A total of 1278 (81%) participants had follow-up with GFR measurements after a median of 5.6 years.

RESULTS

The median ACR at baseline was 0.22 mg/mmol (interquartile range: 0.10-0.51 mg/mmol), the mean ± SD GFR was 104.0 ± 20.1 ml/min, and the mean ± SD GFR decline rate was -0.95 ± 2.23 ml/min per year. Higher baseline ACR levels were associated with a steeper GFR decline in adjusted linear mixed models. Study participants with ACR levels of 0.11 to 0.45 and 0.46 ± 3.40 mg/mmol had a 0.25 ml/min per year (95% confidence interval [95% CI]: -0.03 to 0.53) and 0.31 ml/min per year (95% CI: 0.02-0.60) steeper rate of decline than those with ACR ≤0.10 mg/mmol in multivariable-adjusted analyses. Among study participants with an ACR of <1.13 mg/mmol (defined as the optimal range), those with an ACR of 0.11 to 1.12 mg/mmol (n = 812) had a 0.28 ml/min per year (95% CI: 0.04-0.52) steeper rate of GFR decline than those with an ACR of ≤0.10 mg/mmol (n = 655).

CONCLUSION

A mildly increased ACR is an independent risk factor for faster GFR decline in nondiabetic individuals.

Early Proteinuria Lowering by Angiotensin-Converting Enzyme Inhibition Predicts Renal Survival in Children with CKD

Background Although pharmacotherapeutic proteinuria lowering was found to be nephroprotective in adults, the predictive value of early drug-induced proteinuria reduction for long-term renal survival in pediatric CKD is unknown. We analyzed data from the ESCAPE Trial for a potential association between initial antiproteinuric effect of standardized angiotensin-converting enzyme (ACE) inhibition and renal disease progression in children with CKD.Methods In total, 280 eligible children with CKD stages 2-4 (mean age 11.7 years old, median eGFR 46 ml/min per 1.73 m², 71% congenital renal malformations) received a fixed dose of ramipril (6 mg/m² per day) and were subsequently randomized to conventional or intensified BP control. We assessed initial proteinuria reduction from baseline to first measurement on ramipril (at 2.5±1.3 months). We used multivariable Cox modeling to estimate the association between initial proteinuria reduction and the risk of reaching a renal end point (50% eGFR decline or ESRD), which occurred in 80 patients during 5 years of observation.Results Ramipril therapy lowered proteinuria by a mean of 43.5% (95% confidence interval, 36.3% to 49.9%). Relative to proteinuria reduction <30%, 30%-60% and >60% reduction resulted in hazard ratios (95% confidence intervals) of 0.70 (0.40 to 1.22) and 0.42 (0.22 to 0.79), respectively. This association was independent of age, sex, CKD diagnosis, baseline eGFR, baseline proteinuria, initial BP, and concomitant BP reduction.Conclusions The early antiproteinuric effect of ACE inhibition is associated with long-term preservation of renal function in children with CKD. Proteinuria lowering should be considered an important target in the management of pediatric CKD.

Individual variability in response to renin angiotensin aldosterone system inhibition predicts cardiovascular outcome in patients with type 2 diabetes: A primary care cohort study

AIMS

To assess variability in systolic blood pressure (SBP) and albuminuria (urinary albumin creatinine ratio [UACR]) responses in patients with type 2 diabetes mellitus initiating renin angiotensin aldosterone system (RAAS) inhibition, and to assess the association of response variability with cardiovascular outcomes.

MATERIAL AND METHODS

We performed an observational cohort study in patients with type 2 diabetes who started RAAS inhibition between 2007 and 2013 (n = 1600). Patients were identified from general practices in the Netherlands. Individual response in SBP and UACR was assessed during 15 months' follow-up. Patients were categorized as: good responders (∆SBP <0 mm Hg and ∆UACR <0%); intermediate responders (∆SBP <0 mm Hg and ∆UACR >0% or ∆SBP >0 mm Hg and ∆UACR <0%); or poor responders (∆SBP >0 mm Hg and ∆UACR >0%). Multivariable Cox regression was performed to test the association between initial RAAS inhibition response and subsequent cardiovascular outcomes.

RESULTS

After starting RAAS inhibition, the mean SBP change was -13.2 mm Hg and the median UACR was -36.6%, with large between-individual variability, both in SBP [5th to 95th percentile: 48.5-20] and UACR [5th to 95th percentile: -87.6 to 171.4]. In all, 812 patients (51%) were good responders, 353 (22%) had a good SBP but poor UACR response, 268 (17%) had a good UACR but poor SBP response, and 167 patients (10%) were poor responders. Good responders had a lower risk of cardiovascular events than poor responders (hazard ratio 0.51, 95% confidence interval 0.30-0.86; P = .012).

CONCLUSIONS

SBP and UACR response after RAAS inhibition initiation varied between and within individual patients with type 2 diabetes treated in primary care. Poor responders had the highest risk of cardiovascular events, therefore, more efforts are needed to develop personalized treatment plans for these patients.

Cardiovascular and renal protective role of angiotensin blockade in hypertension with advanced CKD: a subgroup analysis of ATTEMPT-CVD randomized trial

The ATTEMPT-CVD study was prospective randomized active-controlled trial and the main findings had been reported. According to baseline GFR and albuminuria categories, we divided the patients of the ATTEMPT-CVD study into 2 subgroups: (Group 1) the patients with at least one of eGFR of <45 ml/min per 1.73 m2 and UACR of ≥300 mg/g creatinine, defined as G3b and/or A3; (Group 2) the patients except for Group 1, defined as the other patients. In patients with G3b and/or A3, the incidence of cardiovascular events was significantly less in ARB group than in non-ARB group (11 vs 22, respectively) (HR = 0.465: 95%CI = 0.224-0.965; P = 0.040). UACR was significantly less in ARB group than in non-ARB group during follow-up period in patients with G3b and/or A3 (P = 0.0003), while eGFR, plasma BNP levels, and blood pressure were comparable between ARB and non-ARB groups. Allocation to ARB therapy was a significant independent prognostic factor for cardiovascular events in patients with G3b and/or A3 (P = 0.0268). On the other hand, in the other patients, the occurrence of cardiovascular events was comparable between ARB and non-ARB groups. In patients with advanced CKD, ARB-based therapy may confer greater benefit in prevention of cardiovascular events than non-ARB therapy.

Prospective direct comparison of antihypertensive effect and safety between high-dose amlodipine or indapamide in hypertensive patients uncontrolled by standard doses of angiotensin receptor blockers and amlodipine

OBJECTIVE

When hypertension is uncontrolled by routine treatment with an angiotensin II receptor blocker (ARB) and the calcium channel blocker amlodipine (5 mg), the dose of amlodipine can be increased or a diuretic can be added. We investigated the more effective option in a prospective multicenter open-label study.

METHODS

Hypertensive patients were recruited if the target blood pressure (BP) in The Japanese Society of Hypertension 2009 guideline could not be achieved with standard-dose ARB therapy and amlodipine (5 mg).

PATIENTS

Patients were divided into three groups. Group-1 was switched to a combination of irbesartan (100 mg) and amlodipine (10 mg). Group-2A was changed to a combination of irbesartan (100 mg), amlodipine (5 mg), and indapamide, while Group-2B received a standard-dose ARB and amlodipine (5 mg) plus indapamide. Patients were assigned by their attending physicians and were followed for 6 months. The primary endpoint was the antihypertensive effect of each regimen.

RESULTS

Group-1 contained 85 patients, Group-2A had 49 patients, and Group-2B had 4 patients. We only analyzed Group-1 and Group-2A due to the small size of Group-2B. In both groups, systolic BP and diastolic BP were significantly decreased up to 6 months (all p < 0.001). Reduction of systolic BP was greater in Group-1 than Group-2A after 1 month and 6 months (both p < 0.05). Uric acid was increased in Group-2A after 3 months, but not at 6 months.

CONCLUSION

Although both regimens were effective for reducing BP, increasing amlodipine to 10 mg daily controlled hypertension without elevation of serum uric acid.

Variability in response to albuminuria-lowering drugs: true or random?

AIMS

Albuminuria-lowering drugs have shown different effect size in different individuals. Since urine albumin levels are known to vary considerably from day-to-day, we questioned whether the between-individual variability in albuminuria response after therapy initiation reflects a random variability or a true response variation to treatment. In addition, we questioned whether the response variability is drug dependent.

METHODS

To determine whether the response to treatment is random or a true drug response, we correlated in six clinical trials the change in albuminuria during placebo or active treatment (on-treatment) with the change in albuminuria during wash-out (off-treatment). If these responses correlate during active treatment, it suggests that at least part of the response variability can be attributed to drug response variability. We tested this for enalapril, losartan, aliskiren, atrasentan and paricalcitol.

RESULTS

No correlation between the on- and off-treatment albuminuria change was observed in the placebo arm of all clinical trials (R²  < 0.01). However, we observed significant associations between the on- and off-treatment response (R² 0.14 to 0.57; all P < 0.015) for different albuminuria lowering drugs. Additionally, the albuminuria responses strongly correlated when the same individual was re-exposed to the same drug at the same dose: lisinopril 10 mg day^-1 (R²  = 53%; P < 0.01), losartan 50 mg day^-1 (R²  = 63%; P < 0.01).

CONCLUSION

The degree of albuminuria lowering with antialbuminuric drugs varies between patients. This variability in response appears drug-class independent. Identifying which factors determine this initial short-term variation in drug response appears important since the degree of albuminuria lowering is related to subsequent long-term renoprotection.

Effect of Saxagliptin on Renal Outcomes in the SAVOR-TIMI 53 Trial

OBJECTIVE

Dipeptidyl peptidase 4 inhibitors may have a protective effect in diabetic nephropathy.

RESEARCH DESIGN AND METHODS

We studied renal outcomes of 16,492 patients with type 2 diabetes, randomized to saxagliptin versus placebo and followed for a median of 2.1 years in the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53 (SAVOR-TIMI 53) trial.

RESULTS

At baseline, 9,696 (58.8%) subjects had normoalbuminuria (albumin/creatinine ratio [ACR] <30 mg/g), 4,426 (26.8%) had microalbuminuria (ACR 30-300 mg/g), and 1,638 (9.9%) had macroalbuminuria (ACR >300 mg/g). Treatment with saxagliptin was associated with improvement in and/or less deterioration in ACR categories from baseline to end of trial (EOT) (P = 0.021, P < 0.001, and P = 0.049 for individuals with baseline normoalbuminuria, microalbuminuria, and macroalbuminuria, respectively). At 2 years, the difference in mean ACR change between saxagliptin and placebo arms was -19.3 mg/g (P = 0.033) for estimated glomerular filtration rate (eGFR) >50 mL/min/body surface area per 1.73 m² (BSA), -105 mg/g (P = 0.011) for 50 ≥ eGFR ≥ 30 mL/min/BSA, and -245.2 mg/g (P = 0.086) for eGFR <30 mL/min/BSA. Analyzing ACR as a continuous variable showed reduction in ACR with saxagliptin (1 year, P < 0.0001; 2 years, P = 0.0143; and EOT, P = 0.0158). The change in ACR did not correlate with that in HbA_1c (r = 0.041, 0.052, and 0.036; 1 year, 2 years, and EOT, respectively). The change in eGFR was similar in the saxagliptin and placebo groups. Safety renal outcomes, including doubling of serum creatinine, initiation of chronic dialysis, renal transplantation, or serum creatinine >6.0 mg/dL, were similar as well.

CONCLUSIONS

Treatment with saxagliptin improved ACR, even in the normoalbuminuric range, without affecting eGFR. The beneficial effect of saxagliptin on albuminuria could not be explained by its effect on glycemic control.

Screening, diagnosis, and management of patients with Fabry disease: conclusions from a "Kidney Disease: Improving Global Outcomes" (KDIGO) Controversies Conference

Patients with Fabry disease (FD) are at a high risk for developing chronic kidney disease and cardiovascular disease. The availability of specific but costly therapy has elevated the profile of this rare condition. This KDIGO conference addressed controversial areas in the diagnosis, screening, and management of FD, and included enzyme replacement therapy and nonspecific standard-of-care therapy for the various manifestations of FD. Despite marked advances in patient care and improved overall outlook, there is a need to better understand the pathogenesis of this glycosphingolipidosis and to determine the appropriate age to initiate therapy in all types of patients. The need to develop more effective specific therapies was also emphasized.

Long-term Effect of Losartan on Kidney Disease in American Indians With Type 2 Diabetes: A Follow-up Analysis of a Randomized Clinical Trial

OBJECTIVE

To determine whether early administration of losartan slows progression of diabetic kidney disease over an extended period.

RESEARCH DESIGN AND METHODS

We conducted a 6-year clinical trial in 169 American Indians with type 2 diabetes and urine albumin/creatinine ratio <300 mg/g; 84 participants were randomly assigned to receive losartan and 85 to placebo. Primary outcome was a decline in glomerular filtration rate (GFR; iothalamate) to ≤60 mL/min or to half the baseline value in persons who entered with GFR <120 mL/min. At enrollment, GFR averaged 165 mL/min (interquartile range 49-313 mL/min). During the trial, nine persons reached the primary outcome with a hazard ratio (HR; losartan vs. placebo) of 0.50 (95% CI 0.12-1.99). Participants were then followed posttrial for up to 12 years, with treatment managed outside the study. The effect of losartan on the primary GFR outcome was then reanalyzed for the entire study period, including the clinical trial and posttrial follow-up.

RESULTS

After completion of the clinical trial, treatment with renin-angiotensin system inhibitors was equivalent in both groups. During a median of 13.5 years following randomization, 29 participants originally assigned to losartan and 35 to placebo reached the primary GFR outcome with an HR of 0.72 (95% CI 0.44-1.18).

CONCLUSIONS

Long-term risk of GFR decline was not significantly different between persons randomized to early treatment with losartan and those randomized to placebo. Accordingly, we found no evidence of an extended benefit of early losartan treatment on slowing GFR decline in persons with type 2 diabetes.

Prevention of microalbuminuria using early intervention with renin-angiotensin system inhibitors in patients with type 2 diabetes: A systematic review

Hypothesis/objectives:

Early prevention of diabetic nephropathy by way of blocking the renin-angiotensin system (RAS) in patients with normoalbuminuria seems rational, but trials have so far shown conflicting results. The present meta-analysis was undertaken to investigate if such treatment can prevent development of microalbuminuria.

Materials and methods:

We searched MEDLINE, EMBASE and the Cochrane Library (2 June 2014) for randomised controlled trials, with a population of patients with type 2 diabetes and normoalbuminuria, comparing angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs) to placebo. Studies had to have at least 50 participants in each arm and one year of follow-up. Random and fixed effect models were performed as well as trial sequential analysis.

Results:

Six trials were included in the analysis (n=16,921). Overall risk of bias was variable. In a fixed model analysis ACE or ARB treatment was superior to placebo in relation to prevention of development of microalbuminuria, risk ratio 0.84 (95% confidence interval (CI) 0.79–0.88) p<0.001, I²=23%, similar to random model results. Treatment also showed a trend towards a reduction in all-cause mortality(p=0.07).

Conclusions:

We conclude that in patients with type 2 diabetes and normoalbuminuria, early intervention with ACEis or ARBs reduces the risk for development of microalbuminuria.

Serum metabolites predict response to angiotensin II receptor blockers in patients with diabetes mellitus

Background

Individual patients show a large variability in albuminuria response to angiotensin receptor blockers (ARB). Identifying novel biomarkers that predict ARB response may help tailor therapy. We aimed to discover and validate a serum metabolite classifier that predicts albuminuria response to ARBs in patients with diabetes mellitus and micro- or macroalbuminuria.

Methods

Liquid chromatography-tandem mass spectrometry metabolomics was performed on serum samples. Data from patients with type 2 diabetes and microalbuminuria (n = 49) treated with irbesartan 300 mg/day were used for discovery. LASSO and ridge regression were performed to develop the classifier. Improvement in albuminuria response prediction was assessed by calculating differences in R² between a reference model of clinical parameters and a model with clinical parameters and the classifier. The classifier was externally validated in patients with type 1 diabetes and macroalbuminuria (n = 50) treated with losartan 100 mg/day. Molecular process analysis was performed to link metabolites to molecular mechanisms contributing to ARB response.

Results

In discovery, median change in urinary albumin excretion (UAE) was −42 % [Q1–Q3: −69 to −8]. The classifier, consisting of 21 metabolites, was significantly associated with UAE response to irbesartan (p < 0.001) and improved prediction of UAE response on top of the clinical reference model (R² increase from 0.10 to 0.70; p < 0.001). In external validation, median change in UAE was −43 % [Q1–Q35: −63 to −23]. The classifier improved prediction of UAE response to losartan (R² increase from 0.20 to 0.59; p < 0.001). Specifically ADMA impacting eNOS activity appears to be a relevant factor in ARB response.

Conclusions

A serum metabolite classifier was discovered and externally validated to significantly improve prediction of albuminuria response to ARBs in diabetes mellitus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0960-3) contains supplementary material, which is available to authorized users.

Prognostic clinical and molecular biomarkers of renal disease in type 2 diabetes

Diabetic kidney disease occurs in ∼ 25-40% of patients with type 2 diabetes. Given the high risk of progressive renal function loss and end-stage renal disease, early identification of patients with a renal risk is important. Novel biomarkers may aid in improving renal risk stratification. In this review, we first focus on the classical panel of albuminuria and estimated glomerular filtration rate as the primary clinical predictors of renal disease and then move our attention to novel biomarkers, primarily concentrating on assay-based multiple/panel biomarkers, proteomics biomarkers and metabolomics biomarkers. We focus on multiple biomarker panels since the molecular processes of renal disease progression in type 2 diabetes are heterogeneous, rendering it unlikely that a single biomarker significantly adds to clinical risk prediction. A limited number of prospective studies of multiple biomarkers address the predictive performance of novel biomarker panels in addition to the classical panel in type 2 diabetes. However, the prospective studies conducted so far have small sample sizes, are insufficiently powered and lack external validation. Adequately sized validation studies of multiple biomarker panels are thus required. There is also a paucity of studies that assess the effect of treatments on novel biomarker panels and determine whether initial treatment-induced changes in novel biomarkers predict changes in long-term renal outcomes. Such studies can not only improve our healthcare but also our understanding of the mechanisms of actions of existing and novel drugs and may yield biomarkers that can be used to monitor drug response. We conclude that this will be an area to focus research on in the future.

A panel of novel biomarkers representing different disease pathways improves prediction of renal function decline in type 2 diabetes

Objective

We aimed to identify a novel panel of biomarkers predicting renal function decline in type 2 diabetes, using biomarkers representing different disease pathways speculated to contribute to the progression of diabetic nephropathy.

Research Design and Methods

A systematic data integration approach was used to select biomarkers representing different disease pathways. Twenty-eight biomarkers were measured in 82 patients seen at an outpatient diabetes center in The Netherlands. Median follow-up was 4.0 years. We compared the cross-validated explained variation (R²) of two models to predict eGFR decline, one including only established risk markers, the other adding a novel panel of biomarkers. Least absolute shrinkage and selection operator (LASSO) was used for model estimation. The C-index was calculated to assess improvement in prediction of accelerated eGFR decline defined as <-3.0 mL/min/1.73m²/year.

Results

Patients’ average age was 63.5 years and baseline eGFR was 77.9 mL/min/1.73m². The average rate of eGFR decline was -2.0 ± 4.7 mL/min/1.73m²/year. When modeled on top of established risk markers, the biomarker panel including matrix metallopeptidases, tyrosine kinase, podocin, CTGF, TNF-receptor-1, sclerostin, CCL2, YKL-40, and NT-proCNP improved the explained variability of eGFR decline (R² increase from 37.7% to 54.6%; p=0.018) and improved prediction of accelerated eGFR decline (C-index increase from 0.835 to 0.896; p=0.008).

Conclusions

A novel panel of biomarkers representing different pathways of renal disease progression including inflammation, fibrosis, angiogenesis, and endothelial function improved prediction of eGFR decline on top of established risk markers in type 2 diabetes. These results need to be confirmed in a large prospective cohort.

Effect of eprosartan-based antihypertensive therapy on coronary heart disease risk assessed by Framingham methodology in Canadian patients with diabetes: results of the POWER survey

OBJECTIVE

As part of the Physicians' Observational Work on Patient Education According to their Vascular Risk (POWER) survey, we used Framingham methodology to examine the effect of an eprosartan-based regimen on total coronary heart disease (CHD) risk in diabetic patients recruited in Canada.

METHODS

Patients with new or uncontrolled hypertension (sitting systolic blood pressure [SBP] >140 mmHg with diastolic blood pressure <110 mmHg) were identified at 335 Canadian primary care practices. Initial treatment consisted of eprosartan 600 mg/day, which was later supplemented with other antihypertensives as required. Outcomes included change in SBP at 6 months (primary objective) and absolute change in the Framingham 10-year CHD risk score (secondary objective).

RESULTS

We identified an intention-to-treat diabetes population of 195 patients. Most diabetic patients were prescribed two or more antihypertensive drugs throughout the survey. Mean reductions in SBP and diastolic blood pressure were 20.8±14.8 mmHg and 9.5±10.7 mmHg, respectively. The overall absolute mean 10-year CHD risk, calculated using Framingham formulae, declined by 2.9±3.5 points (n=49). Average baseline risk was higher in men than women (14.8±8.6 versus 5.6±1.8 points); men also had a larger average risk reduction (4.2±4.3 versus 1.5±1.3 points). The extent of absolute risk reduction also increased with increasing age (trend not statistically significant).

CONCLUSION

Eprosartan-based therapy substantially reduced arterial blood pressure in our subset of diabetic patients; while there was a slight reduction in Framingham risk, there are indications from our data that both blood pressure control and the wider management of CHD risk in diabetic patients remains suboptimal in Canadian primary care.

Microalbuminuria: a parameter that has changed diabetes care

Diabetic nephropathy is characterised by persistent albuminuria, elevated blood pressure, relentless decline in GFR and enhanced fatal and nonfatal cardiovascular diseases. Microalbuminuria has been central to the development of clinical practise in prevention and treatment of diabetic nephropathy and cardiovascular disease. Treatment-induced and spontaneous remission of microalbuminuria has been reported both in type 1 and type 2 diabetic patients, underlining the importance of sustained elevation of urinary albumin excretion. Recently many new biomarkers have been evaluated in diabetic patients, and apart from urinary proteomics, none has yet outperformed Harry Keen's discovery of microalbuminuria as the best screening tool for diabetic nephropathy. Remission of microalbuminuria preserves renal function. Microalbuminuria has also stood the test of time as a valid powerful independent predictor for fatal and nonfatal cardiovascular outcome in diabetes. Improved glycaemic control, blood pressure reduction, RAS blockade and multifactorial treatment of cardiovascular risk factors reduce the risk of development of micro-and macroalbuminuria, declining renal function and cardiovascular events.

Drug-Induced Reduction in Albuminuria Is Associated with Subsequent Renoprotection: A Meta-Analysis

Albuminuria has been proposed as a surrogate end point in randomized clinical trials of renal disease progression. Most evidence comes from observational analyses showing that treatment-induced short-term changes in albuminuria correlate with risk change for ESRD. However, such studies are prone to selection bias and residual confounding. To minimize this bias, we performed a meta-analysis of clinical trials to correlate the placebo-corrected drug effect on albuminuria and ESRD to more reliably delineate the association between changes in albuminuria and ESRD. MEDLINE and EMBASE were searched for clinical trials reported between 1950 and April 2014. Included trials had a mean follow-up of ≥1000 patient-years, reported ESRD outcomes, and measured albuminuria at baseline and during follow-up. Twenty-one clinical trials involving 78,342 patients and 4183 ESRD events were included. Median time to first albuminuria measurement was 6 months. Fourteen trials tested the effect of renin-angiotensin-aldosterone-system inhibitors and seven trials tested other interventions. We observed variability across trials in the treatment effect on albuminuria (range, -1.3% to -32.1%) and ESRD (range, -55% to +35% risk change). Meta-regression analysis revealed that the placebo-adjusted treatment effect on albuminuria significantly correlated with the treatment effect on ESRD: for each 30% reduction in albuminuria, the risk of ESRD decreased by 23.7% (95% confidence interval, 11.4% to 34.2%; P=0.001). The association was consistent regardless of drug class (P=0.73) or other patient or trial characteristics. These findings suggest albuminuria may be a valid substitute for ESRD in many circumstances, even taking into account possible other drug-specific effects that may alter renal outcomes.

Urinary excretion of RAS, BMP, and WNT pathway components in diabetic kidney disease

The renin–angiotensin system (RAS), bone morphogenetic protein (BMP), and WNT pathways are involved in pathogenesis of diabetic kidney disease (DKD). This study characterized assays for urinary angiotensinogen (AGT), gremlin‐1, and matrix metalloproteinase 7 (MMP‐7), components of the RAS, BMP, and WNT pathways and examined their excretion in DKD. We measured urine AGT, gremlin‐1, and MMP‐7 in individuals with type 1 diabetes and prevalent DKD (n = 20) or longstanding (n = 61) or new‐onset (n = 10) type 1 diabetes without DKD. These urine proteins were also quantified in type 2 DKD (n = 11) before and after treatment with candesartan. The utilized immunoassays had comparable inter‐ and intra‐assay and intraindividual variation to assays used for urine albumin. Median (IQR) urine AGT concentrations were 226.0 (82.1, 550.3) and 13.0 (7.8, 20.0) μg/g creatinine in type 1 diabetes with and without DKD, respectively (P < 0.001). Median (IQR) urine gremlin‐1 concentrations were 48.6 (14.2, 254.1) and 3.6 (1.7, 5.5) μg/g, respectively (P < 0.001). Median (IQR) urine MMP‐7 concentrations were 6.0 (3.8, 10.5) and 1.0 (0.4, 2.9) μg/g creatinine, respectively (P < 0.001). Treatment with candesartan was associated with a reduction in median (IQR) urine AGT/creatinine from 23.5 (1.6, 105.1) to 2.0 (1.4, 13.7) μg/g, which did not reach statistical significance. Urine gremlin‐1 and MMP‐7 excretion did not decrease with candesartan. In conclusion, DKD is characterized by markedly elevated urine AGT, MMP‐7, and gremlin‐1. AGT decreased in response to RAS inhibition, suggesting that this marker reflects therapeutic response. Urinary components of the RAS, BMP, and WNT pathways may identify risk of DKD and aid development of novel therapeutics.

Urine angiotensinogen, matrix metalloproteinase‐7, and gremlin‐1 concentrations are markedly elevated in people with type 1 diabetes and kidney disease, compared with those with recently diagnosed type 1 diabetes or longstanding type 1 diabetes without kidney disease. Treatment with an inhibitor of the renin–angiotensin system tended to reduce urine angiotensinogen concentration, but not urine matrix metalloproteinase‐7 or gremlin‐1.

'Progressive diabetic nephropathy. How useful is microalbuminuria?: contra'

The concept of microalbuminuria has been central to the development of clinical practice and research in the area of diabetic kidney disease (DKD). However, in recent times, the value of a paradigm of DKD based solely on microalbuminuria has been questioned. Although both the absolute level and rate of change of microalbuminuria are linked to the development and progression of DKD, microalbuminuria on its own lacks the necessary sensitivity or specificity to accurately predict kidney outcomes for people with diabetes. The development of microalbumiuria can no longer be viewed as a committed and irreversible stage of DKD, as spontaneous remission is now reported as a common occurrence. In addition, the absence of microalbuminuria or its progression to proteinuria does not signify that an individual patient is safe from a progressive decline in glomerular filtration rate (GFR). Furthermore, although reductions in albuminuria within the microalbuminuric range can be linked to a slower GFR decline in observational studies, this relationship has not been robustly demonstrated in intervention studies. Conclusions regarding the kidney health of individuals with diabetes will continue to be flawed if an inappropriate emphasis is placed on the presence or absence of albuminuria or changes in albuminuria within the microalbuminuric range. This has important implications in terms of undermining the value of microalbuminuria as a surrogate renal end point for intervention trials. There is a need to develop broader models of progressive DKD that include novel pathways and risk markers apart from those related to the traditional 'albuminuric pathway' to renal impairment.

Markers of and risk factors for the development and progression of diabetic kidney disease

Diabetic kidney disease (DKD) occurs in 25%-40% of patients with diabetes. Given the dual problems of a significant risk of progression from DKD to end-stage renal disease (ESRD) and increased cardiovascular morbidity and mortality, it is important to identify patients at risk of DKD and ESRD and initiate protective renal and cardiovascular therapies. The importance of preventive therapy is emphasized further by worldwide increases in the incidence of diabetes. This review summarizes the evidence regarding the prognostic value and benefits of targeting established and novel risk markers for DKD development and progression. Family history of DKD, smoking history, and glycemic, blood pressure, and plasma lipid level control are established factors for identifying people at greatest risk of DKD development and progression. Absolute albumin excretion rate (AER) and glomerular filtration rate (GFR) measurements also are important, although AER categorization generally lacks the necessary specificity and sensitivity, and estimates of declining GFR are compromised by methodological limitations for GFRs in the normal-to-high range. Emerging risk markers for progressive loss of kidney function include markers of oxidation and inflammation, profibrotic cytokines, uric acid, advanced glycation end products, functional and structural markers of vascular dysfunction, kidney structural changes, and tubular biomarkers. Among these, the most promising are serum uric acid and soluble tumor necrosis factor receptor (type 1 and type 2) levels, especially in relation to GFR changes. At present, these can only be considered as risk markers because they only identify an individual at increased risk of progressive DKD and not necessarily related to the causal pathway promoting kidney damage. Further work is needed to establish whether modulating these factors improves the prognosis in DKD. Although change in urinary peptidome levels also is a promising marker, there currently is neither a clinical assay nor adequate studies defining its prognostic value. Until these or other novel markers become available for clinical use, predictive accuracy often may be increased with greater attention to established markers.

What should be the blood pressure target for patients with chronic kidney disease?

PURPOSE OF REVIEW

Persons with chronic kidney disease (CKD) exhibit a disproportionate burden of elevated blood pressure (BP) with a high prevalence of premature end-stage renal disease and cardiovascular events.

RECENT FINDINGS

Results of recent randomized controlled clinical trials suggest that most patients with reduced estimated glomerular filtration rate (eGFR) and hypertension experience optimal clinical outcomes when SBP is less than 140 mmHg and DBP is less than 90 mmHg. The benefit of additional lowering of SBP to less than 130 mmHg and DBP to less than 80 mmHg remains controversial, and appears to be of most benefit to the subset of CKD patients with proteinuria (>300 mg/day). The combination of a diuretic and an angiotensin receptor blocker (ARB) or angiotensin-converting enzyme inhibitor (ACEI) has demonstrated particular promise in patients with reduced eGFR and proteinuria.

SUMMARY

A practical approach in clinical practice for the treatment of elevated BP in persons with CKD is to achieve a BP less than 140/90 mmHg with a combination of diuretic and an ARB or ACEI. Consideration for a lower BP goal and other therapeutic and nontherapeutic interventions can be made based on the cause of CKD, presence of proteinuria, or other coexisting medical conditions.

The effect of RAAS blockade on the progression of diabetic nephropathy

The renin-angiotensin-aldosterone system (RAAS) has a key role in the regulation of blood pressure, sodium and water balance, and cardiovascular and renal homeostasis. In diabetic nephropathy, excessive activation of the RAAS results in progressive renal damage. RAAS blockade using angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is the cornerstone of treatment of diabetic renal disease. Alternative RAAS-blockade strategies include renin inhibition and aldosterone blockade. Data from small initial studies of these agents are promising. However, single-agent interventions do not fully block the RAAS and patients treated with these therapies remain at high residual renal risk. Approaches to optimize drug responses include dietary changes and increasing dosages. The theoretically attractive option of combining different RAAS interventions has also been tested in clinical trials but long-term outcomes were disappointing. However, dual RAAS blockade might represent a good therapeutic option for specific patients. A better knowledge of the pathophysiology of the RAAS is crucial to fully understand the mechanisms of action of RAAS blockers and to exploit their renoprotective effects. Moreover, lifestyle interventions or diagnostic tools might be used to optimize RAAS blockade and identify those patients who are most likely to benefit from the therapy.

Reduction and residual proteinuria are therapeutic targets in type 2 diabetes with overt nephropathy: a post hoc analysis (ORIENT-proteinuria)

BACKGROUND

Proteinuria is a major predictor for progression of renal disease, including diabetic nephropathy. In a post hoc analysis of the ORIENT, a double-blinded randomized trial of 566 type 2 diabetic patients with nephropathy, we examined the risk association of composite renal outcome [end-stage renal disease, ESRD, doubling of serum creatinine (SCr) and death] with baseline, change and residual urinary protein/creatinine ratio (UPCR).

METHODS

We estimated the hazard ratios (HRs) with 95% confidence interval (CI) of composite renal outcome with baseline UPCR (low <1.0 g/gCr; moderate ≥ 1.0 g/gCr, <3.0 g/gCr and high ≥ 3.0 g/gCr) as well as percentage reduction of UPCR (Δ) (worsening: <0%; moderate: ≥ 0%, <30% and high ≥ 30%) and residual UPCR at 24 weeks (remission <1.0 g/gCr; moderate ≥ 1.0 g/gCr, <3.0 g/gCr and heavy ≥ 3.0 g/gCr).

RESULTS

Compared with the low group with baseline UPCR < 1.0 g/gCr, the respective HRs with 95% CI in the moderate and high UPCR groups were 3.02 (1.76-5.19) and 9.24 (5.43-15.73). Compared with patients with a worsening UPCR (<0%) at 24 weeks, the HR was 0.54 (0.39-0.74) in those with ≥ 0%, <30% ΔUPCR and 0.43 (0.31-0.61) in those with ≥ 30% ΔUPCR. Compared with the remission at 24 weeks, the HR was 2.12 (1.28-3.49) in moderate residual proteinuria and 4.59 (2.74-7.69) in heavy residual proteinuria. Compared with patients with residual UPCR ≥ 1.0 g/gCr and ΔUPCR <30%, the HR in those with ΔUPCR ≥ 30% and residual UPCR<1.0 g/gCr was 0.38 (0.22-0.64).

CONCLUSIONS

In patients with type 2 diabetes and overt nephropathy, over 30% reduction of UPCR compared with baseline and/or residual UPCR<1.0 g/gCr at 24 weeks predicted renoprotection. These values may be used as targets to guide anti-proteinuric and renoprotective therapy in diabetic nephropathy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00141453.

Early inhibition of the renin-angiotensin system improves the long-term graft survival of single pediatric donor kidneys transplanted in adult recipients

Transplanting single pediatric donor kidneys into adult recipients has an increased risk of hyperfiltration injury and graft loss. It is unknown if renin-angiotensin system (RAS) blockers are beneficial in this setting. We retrospectively analyzed 94 adults who received single kidneys from donors <10 years old during 1996-2009. The recipients were divided into group 1 with RAS blockers (n = 40) and group 2 without RAS blockers (n = 54) in the first year of transplant. There was no significant difference in any donor/recipient demographic between the two groups. Graft function, incidence of delayed graft function, acute rejection, and persistent proteinuria were not statistically different either. Kaplan-Meier estimated death-censored graft survivals were significantly better in group 1 than in group 2: 95 vs. 81.2%, 82.4 vs. 61.2%, 72.6 vs. 58.5%, and 68.5 vs. 47.2% at 1, 3, 5, and 7 years, respectively (log rank P = 0.043). Multivariable analysis found persistent proteinuria was a risk factor for graft loss (OR 2.70, 95% CI 1.33-5.49, P = 0.006), while RAS blockers reduced the risk of graft loss (OR 0.38, 95% CI 0.18-0.79, P = 0.009). Early RAS blockade therapy in the first year of transplant is associated with superior long-term graft survival among adults transplanted with single pediatric donor kidneys.

Viper venom for diabetic nephropathy

Diabetic nephropathy is the leading cause of end-stage renal disease in the United States. Renin-angiotensin-aldosterone system (RAAS) blockers are thought to have a specific renoprotective effect in diabetes. Hirst et al. report the results of randomized clinical trials assessing the effects of RAAS inhibitors on urinary albumin excretion levels in diabetic patients. Although reductions in urinary albumin excretion were observed, whether RAAS inhibitors offer additional protection over other antihypertensive agents is unclear.

The emerging concept of chronic kidney disease without clinical proteinuria in diabetic patients

The natural history of diabetic nephropathy was defined in the 1980s on the basis of longitudinal studies undertaken in patients with type 1 and type 2 diabetes. However, an increasing number of studies have indicated that certain diabetic patients do not present with the same evolution as was then defined: for example, some often have significant initial deterioration of glomerular filtration rate whereas, in others, microalbuminuria is reduced spontaneously. Chronic kidney disease (CKD) may be accompanied, rather than preceded, by macroalbuminuria, or it may develop in patients with microalbuminuria or even in those with albuminuria levels that revert to normal. CKD can also develop in patients whose albuminuria levels remain normal. Progression to macroalbuminuria is, in fact, less frequent than regression to normoalbuminuria or no change in microalbuminuria status in diabetic patients with microalbuminuria, especially in type 1 diabetes. Some experience progressive deterioration of renal function due to diabetes without developing significant proteinuria: this is seen fairly frequently and can affect 50% of patients with renal insufficiency. Such cases are more often older patients treated with renin-angiotensin system blockers who usually have a history of cardiovascular disease. Evolution to end-stage renal disease is slower in this subgroup of patients, although histological analyses may show surprisingly advanced glomerular lesions. The main parameters of surveillance remain regular monitoring of glycaemia, and control of blood pressure and the evolution of initial albuminuria levels. Nevertheless, why some patients exhibit conventional diabetic nephropathy while others have slower declines in renal function associated with normal albuminuria levels or microalbuminuria is unclear. It is hoped that the new pathological classification of diabetic nephropathy will help in our understanding of these discrepancies.

Proteinuria should be used as a surrogate in CKD

Surrogate end points of renal failure are instrumental to the testing of new treatments in patients with chronic kidney disease, the natural history of which is characterized by a slow, asymptomatic decline in renal function. The magnitude of proteinuria is widely recognized as a marker of the severity of glomerulopathy. Population-based studies have identified proteinuria as a predictor of future decline in glomerular filtration rate and of the development of end-stage renal disease. More importantly, a reduction in proteinuria invariably translates into a protection from renal function decline in patients with diabetic and nondiabetic renal disease with overt proteinuria. Thus, proteinuria should be considered a valuable surrogate end point for clinical trials in patients with proteinuric renal diseases.

The kidney in type 2 diabetes therapy

Renal and cardiovascular complications make type 2 diabetes one of the most morbid conditions in medicine. The kidney frequently gets involved in this "multi-organ disease". Of the large proportion of patients who progress with further loss of renal function, most prematurely die or end up in dialysis. Many interventions have targeted a decelerated progression of renal function loss, including metabolic control, blood pressure, and lipid management. Recently, modulation of the renin-angiotensin-aldosterone-system (RAAS) have been combined with the existing therapeutic armamentarium. RAAS inhibitors lower blood pressure and decrease albuminuria which leads to additionally protective renal and cardiovascular effects. Although this has been the success story of the last two decades, it has still made a relatively small contribution to patient welfare, since the residual risk in patients that received this optimal care remains extremely high. New treatment strategies are required that further slow the progression of renal and cardiovascular functions. Recently, several pathways have been investigated, targeting traditional risk factors such as blood pressure- and lipid-lowering strategies with unexpected results. Furthermore, novel targets and drugs have been identified. Preliminary studies on surrogate markers for renal outcome show a great potential for additive renal protection, such that in many cases hard endpoint trials are initiated. Novel interventions, which are reviewed here, include vitamin D receptor activators, RAASi with direct renin inhibitors or aldosterone antagonists, endothelin-antagonist, inflammation suppression with pentoxyfillin, MCP-1 synthesis inhibitors, or with Nrf2 agonists. Despite the current depressing situation of type 2 diabetic patients with nephropathy, new treatment options are under development to reduce the high morbidity and mortality associated with this universal ever-increasing disease threat.