A randomized, double-blind, placebo-controlled trial to evaluate the effect of enalapril in patients with clinical diabetic nephropathy

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.

Secular Trend in GFR Decline in Non-Dialysis CKD Based on Observational Data From Standard of Care Arms of Trials

RATIONALE & OBJECTIVE

The standard of care (SoC) group of randomized controlled trials (RCTs) is a useful setting to explore the secular trends in kidney disease progression because implementation of best clinical practices is pursued for all patients enrolled in trials. This meta-analysis evaluated the secular trend in the change of glomerular filtration rate (GFR) decline in the SoC arm of RCTs in chronic kidney disease (CKD) published in the last 30 years.

STUDY DESIGN

Systematic review and meta-analysis of the SoC arms of RCTs analyzed as an observational study.

SETTING & STUDY POPULATIONS

Adult patients with CKD enrolled in the SoC arm of RCTs.

SELECTION CRITERIA FOR STUDIES

Phase 3 RCTs evaluating GFR decline as an outcome in SoC arms.

DATA EXTRACTION

Two independent reviewers evaluated RCTs for eligibility and extracted relevant data.

ANALYTICAL APPROACH

The mean of GFR declines extracted in the SoC arm of selected RCTs were pooled by using a random effects model. Meta-regression analyses were performed to identify factors that may explain heterogeneity.

RESULTS

The SoC arms from 92 RCTs were included in the meta-analysis with a total of 32,202 patients. The overall mean GFR decline was-4.00 (95% CI, -4.55 to-3.44) mL/min/1.73m2 per year in the SoC arms with a high level of heterogeneity (I2, 98.4% [95% CI, 98.2-98.5], P<0.001). Meta-regression analysis showed an association between publication year (β estimate, 0.09 [95% CI, 0.032-0.148], P=0.003) and reduction in GFR over time. When evaluating publication decade categorically, GFR decline was-5.44 (95% CI, -7.15 to-3.73), -3.92 (95% CI, -4.82 to-3.02), and -3.20 (95% CI, -3.75 to -2.64) mL/min/1.73m2 per year during 1991-2000, 2001-2010, and 2011-2023, respectively. Using meta-regression, the heterogeneity of GFR decline was mainly explained by age and proteinuria.

LIMITATIONS

Different methods assessing GFR in selected trials and observational design of the study.

CONCLUSIONS

In the last 3 decades, GFR decline has decreased over time in patients enrolled in RCTs who received the standard of care.

TRIAL REGISTRATION

Registered at PROSPERO with record number CRD42022357704.

PLAIN-LANGUAGE SUMMARY

This study evaluated the secular trend in the change in glomerular filtration rate (GFR) decline in the placebo arms of randomized controlled trials (RCTs) that were studying approaches to protect the kidneys in the setting of chronic kidney disease. The placebo groups of RCTs are useful for examining whether the rate of progression of kidney disease has changed over time. We found an improvement in the slope of change in GFR over time. These findings suggest that adherence to standards of kidney care as implemented in clinical trials may be associated with improved clinical outcomes, and these data may inform the design of future RCTs in nephrology.

ACEI and ARB Lower the Incidence of End-Stage Renal Disease among Patients with Diabetic Nephropathy: A Meta-analysis

Objective

This study explores the effects of Angiotensin-Converting Enzyme Inhibitors (ACEI) or Angiotensin Receptor Blockers (ARB) on the incidence of end-stage renal disease (ESRD) in diabetic nephropathy (DN) patients.

Methods

Literatures were searched in PubMed, Embase, Medline, CENTRAL, and CNKI databases. These literatures included a randomized controlled trial to evaluate the efficacy of ACEI and ARB among patients with DN. The endpoint event included the occurrence of ERSD. Risk ratio (RR) and 95% confidence interval (CI) were used to represent the combined effect size. A fixed-effect model was used to analyze if heterogeneity did not exist between literatures. If heterogeneity exists between literatures, a random-effect model was used to analyze. The source of heterogeneity was explored by subgroup analysis and sensitivity analysis.

Results

A total of 11 literatures were included in the study. The RR of ESRD was 0.79 (95% CI (0.79, 0.90), Z = 3.58, P = 0.0003) in the patients treated with RAS blockers compared with placebo, and there was no heterogeneity between studies (Chi² = 5.09, P = 0.88, I² = 0%). The funnel plot showed that the scatter point was biased to the left with publication bias. The RR of ESRD was 0.63 (95% CI (0.41, 0.95), Z = 2.18, P = 0.03) in the patients treated with ACEI compared with placebo. There was no heterogeneity between studies (Chi² = 2.23, P = 0.95, I² = 0%). Compared with placebo, RR of ESRD among patients with ARB intervention was 0.81 (95% CI (0.71, 0.93), Z = 3.00, P = 0.003). There was no heterogeneity between studies (Chi² = 1.49, P = 0.48, I² = 0%).

Conclusion

ACEI and ARB can reduce the risk of ESRD among diabetic nephropathy patients.

Comparative risk of new-onset hyperkalemia for antihypertensive drugs in patients with diabetic nephropathy: A Bayesian network meta-analysis

Several randomised controlled trials (RCTs) have evaluated the risk of hyperkalemia of antihypertensive drugs on diabetic nephropathy, yet the results are conflicting. We searched MEDLINE, Embase, The Cochrane Library, and Web of Science for RCTs investigating the risk of antihypertensive drugs on hyperkalemia in diabetic nephropathy from inception to May 31, 2020. Direct comparative meta-analysis showed that the proportion of patients with hyperkalemia was significantly higher in the ARB, aldosterone antagonist, renin inhibitor group than in the placebo group. Moreover, the risk of hyperkalemia in the ARB group was higher than that in the CCB group. Network meta-analysis showed the risk of hyperkalemia in the ARB, aldosterone antagonist, and renin inhibitor group was higher than in the placebo group, but there was no statistical difference between the CCB, ACEI, β blocker, endothelin inhibitor, and diuretic groups than in the placebo group. The possibility of antihypertensive drugs in risk of hyperkalemia being the worst treatment was aldosterone antagonist (98.8%), followed by ARB (73.8%), renin inhibitor (63.8%), diuretic (53.1%), ACEI (46.9%), β blocker (36.8%), endothelin inhibitor (35.2%), placebo (27.1%), and finally CCB (14.3.1%). Therefore, aldosterone antagonist seems worse than other antihypertensive drugs in the risk of hyperkalemia in patients with diabetic nephropathy.

Effects of renin-angiotensin system blockers on renal and cardiovascular outcomes in patients with diabetic nephropathy: a meta-analysis of randomized controlled trials

PURPOSE

This study aimed to evaluate the effect f angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) on renal or cardiovascular outcomes in patients with diabetic nephropathy (DN).

METHODS

PubMed, Embase, and Cochrane Library were searched for randomized controlled trials (RCTs) evaluating the treatment effects of ACEI and ARB on renal or cardiovascular outcomes in patients with DN until August 2017. The outcomes included end-stage renal disease (ESRD), doubling of serum creatinine levels, all-cause mortality, major cardiovascular events (MACEs), myocardial infarction (MI), stroke, and cardiac death. Relative risks (RR) with 95% confidence intervals (CIs) were used for calculating the summary results using a random-effects model.

RESULTS

Twenty-four RCTs including 57,818 patients with DN and 891 events of ESRD, 1050 doubling of serum creatinine concentration, 4352 all-cause mortality, 6342 MACEs, 1073 MI, 2900 stroke, and 1674 cardiac deaths were reported. Overall, the summary results suggested that in patients with DN, receiving ACEI did not have a significant effect on ESRD, doubling of serum creatinine levels, all-cause mortality, MI, stroke, and cardiac death, while ACEI significantly reduced the risk of total MACEs. Furthermore, ARB therapy was associated with a low risk of ESRD and doubling of serum creatinine levels, while it did not differ significantly on all-cause mortality, MACEs, MI, stroke, and cardiac death in patients with DN.

CONCLUSIONS

Patients with DN receiving ACEI had significantly reduced the risk of total MACEs, and ARB could reduce the incidence of ESRD and the doubling of serum creatinine levels.

Effects of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers on cardiovascular events in patients with diabetes and overt nephropathy: a meta-analysis of randomised controlled trials

OBJECTIVE

The efficacy of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in reducing cardiovascular outcomes in patients with diabetes and overt nephropathy is still a controversial issue.

METHODS

We systematically searched MEDLINE, Embase and Cochrane Library for randomised controlled trials.

RESULTS

Thirteen trials containing 4638 patients with diabetes and overt nephropathy were included. Compared with controls, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker treatment did not reduce the risk of cardiovascular events (odds ratio 0.94, 95% confidence interval 0.86 to 1.03, P=0.18; I²=0.0%, P=0.75). Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy reduced the odds of heart failure events by 29% (0.71, 0.61 to 0.83, P<0.001; I²=0%, P=0.78). The results indicated no significant differences between the two treatment regimens with regard to the frequency of MI (0.95, 0.76 to 1.19, P=0.64), stroke (1.20, 0.83 to 1.74, P=0.32), cardiovascular death (1.26, 0.96 to 1.65, P=0.09) and all-cause mortality (0.98, 0.86 to 1.12, P=0.73). Among all kinds of adverse effects, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy increased the incidence of hyperkalemia (2.26, 1.42 to 3.61, P=0.001).

CONCLUSION

This study demonstrated that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers did not reduce cardiovascular events in patients with diabetes and overt nephropathy.

Should BP targets be lower in diabetic patients with microalbuminuria or nephropathy? A systematic review of randomised controlled trials

Does antihypertensive treatment in normotensive patients with diabetic nephropathy alter the progression of kidney failure? We have evaluated studies of renal function which either assessed the effects of different therapeutic blood pressure (BP) goals, or the effects of antihypertensive therapy within the normotensive BP range. Need for renal replacement therapy was regarded as the most valid end point for assessment of deterioration of nephropathy, and change in the glomerular filtration rate (GFR) was regarded as a valid surrogate parameter. Five randomised controlled trials (RCTs) which included normotensive and hypertensive type 1 and type 2 diabetic patients have investigated the effect of lowering of BP within the normotensive range, or from hypertensive values to within the normotensive range. Albumin excretion in urine decreased in the groups randomised to lower BP values, but none of the trials demonstrated any beneficial effect of this intervention on the progression of kidney failure as assessed by the course of GFR. In conclusion, in diabetic patients with microalbuminuria or overt nephropathy, there is no evidence in the literature from RCTs for a beneficial effect of lowering BP within the normotensive range on the risk of kidney replacement therapy or on the loss of glomerular function.

Renin-Angiotensin System Inhibitors and Kidney and Cardiovascular Outcomes in Patients With CKD: A Bayesian Network Meta-analysis of Randomized Clinical Trials

BACKGROUND

There is much uncertainty regarding the relative effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) in populations with chronic kidney disease (CKD).

STUDY DESIGN

Systematic review and Bayesian network meta-analysis.

SETTING & POPULATION

Patients with CKD treated with renin-angiotensin system (RAS) inhibitors.

SELECTION CRITERIA FOR STUDIES

Randomized trials in patients with CKD treated with RAS inhibitors.

PREDICTOR

ACE inhibitors and ARBs compared to each other and to placebo and active controls.

OUTCOME

Primary outcome was kidney failure; secondary outcomes were major cardiovascular events, all-cause death.

RESULTS

119 randomized controlled trials (n = 64,768) were included. ACE inhibitors and ARBs reduced the odds of kidney failure by 39% and 30% (ORs of 0.61 [95% credible interval, 0.47-0.79] and 0.70 [95% credible interval, 0.52-0.89]), respectively, compared to placebo, and by 35% and 25% (ORs of 0.65 [95% credible interval, 0.51-0.80] and 0.75 [95% credible interval, 0.54-0.97]), respectively, compared with other active controls, whereas other active controls did not show evidence of a significant effect on kidney failure. Both ACE inhibitors and ARBs produced odds reductions for major cardiovascular events (ORs of 0.82 [95% credible interval, 0.71-0.92] and 0.76 [95% credible interval, 0.62-0.89], respectively) versus placebo. Comparisons did not show significant effects on risk for cardiovascular death. ACE inhibitors but not ARBs significantly reduced the odds of all-cause death versus active controls (OR, 0.72; 95% credible interval, 0.53-0.92). Compared with ARBs, ACE inhibitors were consistently associated with higher probabilities of reducing kidney failure, cardiovascular death, or all-cause death.

LIMITATIONS

Trials with RAS inhibitor therapy were included; trials with direct comparisons of other active controls with placebo were not included.

CONCLUSIONS

Use of ACE inhibitors or ARBs in people with CKD reduces the risk for kidney failure and cardiovascular events. ACE inhibitors also reduced the risk for all-cause mortality and were possibly superior to ARBs for kidney failure, cardiovascular death, and all-cause mortality in patients with CKD, suggesting that they could be the first choice for treatment in this population.

Utility and validity of estimated GFR-based surrogate time-to-event end points in CKD: a simulation study

BACKGROUND

There is interest in surrogate end points for clinical trials of chronic kidney disease progression because currently established end points-end-stage renal disease (ESRD) and doubling of serum creatinine level-are late events, requiring large clinical trials with long follow-up. Doubling of serum creatinine level is equivalent to a 57% decline in estimated glomerular filtration rate (eGFR). We evaluated type 1 error and required sample size for clinical trials using surrogate end points based on lesser eGFR declines.

STUDY DESIGN

Simulation study.

SETTING & PARTICIPANTS

Simulations evaluating 3,060 scenarios representative of 19 treatment comparisons in 13 chronic kidney disease clinical trials.

INDEX TESTS

Surrogate end points defined as composite end points based on ESRD and either 30% or 40% eGFR declines.

REFERENCE TEST

Clinical outcome (ESRD) for type 1 error. Established end point (composite of ESRD and 57% eGFR decline) for required sample size.

RESULTS

Use of the 40% versus 57% eGFR decline end point consistently led to a reduction in sample size > 20% while maintaining risk for type 1 error < 10% in the presence of a small acute effect (<1.25mL/min/1.73m(2)) for: (1) 2-, 3-, or 5-year trials with a high mean baseline eGFR (67.5mL/min/1.73m(2)), and (2) 2-year trials with an intermediate mean baseline eGFR (42.5mL/min/1.73m(2)). Use of the 30% versus the 40% eGFR decline end point often led to moderately larger reductions in sample size in the absence of an acute effect, but not in the presence of acute effects.

LIMITATIONS

The complexity of eGFR trajectories prevented evaluation of all scenarios for clinical trials.

CONCLUSIONS

Use of end points based on 30% or 40% eGFR declines is an appropriate strategy to reduce sample size in certain situations. However, risk for type 1 error is increased in the presence of acute effects, particularly for 30% eGFR declines. The decision to use these end points should be made after thorough evaluation of their expected performance under the conditions of specific clinical trials.

Residual renal function in hemodialysis patients: the role of Angiotensin-converting enzyme inhibitor in its preservation

Residual Renal function (RRF) has an important role in the overall morbidity and mortality in hemodialysis patients. The role of angiotensin-converting enzyme inhibitor (ACEi) in preserving renal function in chronic proteinuric nephropathies is well documented. We test the hypothesis that enalapril (an ACEi) slows the rate of decline of RRF in patients starting hemodialysis. A prospective, randomized open-label study was carried out. 42 patients were randomized in two groups either in treatment with enalapril or no treatment at all. Our study has proven that enalapril has a significant effect on preserving residual renal function in patients starting dialysis at least during the first 12 months from the initiation of the hemodialysis. Further studies are necessary in order to investigate the potential long-term effect of ACEi on residual renal function and on morbidity and mortality in patients starting hemodialysis.

Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and combined therapy in patients with micro- and macroalbuminuria and other cardiovascular risk factors: a systematic review of randomized controlled trials

BACKGROUND

A recent clinical trial showed harmful renal effects with the combined use of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin-II receptor blockers (ARB) in people with diabetes or vascular disease. We examined the benefits and risks of these agents in people with albuminuria and one or more cardiovascular risk factors.

METHODS

MEDLINE, EMBASE and Renal Health Library were searched for trials comparing ACEI, ARB or their combination with placebo or with one another in people with albuminuria and one or more cardiovascular risk factor.

RESULTS

Eighty-five trials (21,708 patients) were included. There was no significant reduction in the risk of all-cause mortality or fatal cardiac-cerebrovascular outcomes with ACEI versus placebo, ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. There was a significant reduction in the risk of nonfatal cardiovascular events with ACEI versus placebo but not with ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. Development of end-stage kidney disease and progression of microalbuminuria to macroalbuminuria were reduced significantly with ACEI versus placebo and ARB versus placebo but not with combined therapy with ACEI + ARB versus monotherapy.

CONCLUSIONS

ACEI and ARB exert independent renal and nonfatal cardiovascular benefits while their effects on mortality and fatal cardiovascular disease are uncertain. There is a lack of evidence to support the use of combination therapy. A comparative clinical trial with ACE, ARB and its combination in people with albuminuria and a cardiovascular risk factor is warranted.

Effects of renin-angiotensin system blockers on renal outcomes and all-cause mortality in patients with diabetic nephropathy: an updated meta-analysis

BACKGROUND

In contrast to previous studies, recent data questioned the ability of renin-angiotensin-aldosterone system (RAAS) blockers to delay progression of diabetic nephropathy. This study evaluated the effect of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) in patients with diabetic nephropathy.

METHODS

A systematic literature search of MEDLINE/PubMed and EMBASE databases was performed to identify randomized trials published up to June 2007 comparing the effects of ACEIs or ARBs with placebo and/or a regimen not including a RAAS blocker on the incidence of end-stage renal disease (ESRD), doubling of serum creatinine (DSC), or death from any cause in patients with diabetic nephropathy. Treatment effects were summarized as relative risks (RRs) using the Mantel-Haenszel fixed-effects model.

RESULTS

Of the 1,028 originally identified studies, 24 fulfilled the inclusion criteria (20 using ACEIs and 4 using ARBs). Use of ACEIs was associated with a trend toward reduction of ESRD incidence (RR 0.70; 95% confidence interval (CI) 0.46-1.05) and use of ARBs with significant reduction of ESRD risk (RR 0.78; 95% CI 0.67-0.91). Both drug classes were associated with reduction in the risk of DSC (RR 0.71; 95% CI 0.56-0.91 for ACEIs and RR 0.79; 95% CI 0.68-0.91 for ARBs) but none affected all-cause mortality (RR 0.96; 95% CI 0.85-1.09 for ACEIs and RR 0.99; 95% CI 0.85-1.16 for ARBs).

CONCLUSION

Treatment of patients with diabetic nephropathy with a RAAS blocker reduces the risks of ESRD and DSC, but does not affect all-cause mortality. These findings are added to the evidence of a renoprotective role of RAAS blockers in such patients.

A cost-effectiveness analysis of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in diabetic nephropathy

The aim of this study was to estimate the cost-effectiveness of renin-angiotensin-aldosterone system blockers in patients with diabetic nephropathy. A cost-effectiveness analysis was performed based on a meta-analysis of studies investigating the effect of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) as part of a treatment regimen on the incidence of end-stage renal disease (ESRD) in patients with diabetic nephropathy. The primary outcome was the cost to prevent 1 patient from developing ESRD. Cost analysis was performed from a third-party payer perspective in 2006 US dollars. As part of a treatment regimen, ARBs significantly reduced the incidence of ESRD and doubling of serum creatinine concentration (P<.05) but not total mortality. The cost to prevent 1 patient from developing ESRD was $31,729 (95% confidence interval, $19,443-$85,442; P<.01), $189,190 (P=.13) and $51,585 (P=.068) for patients receiving ARBs, ACE inhibitors, or either of them, respectively. This study demonstrates that blocking the RAAS, which delays the progression to ESRD, appears to be cost-effective. The current analysis favors ARBs in terms of cost-effectiveness.

Effect of valsartan versus lisinopril on peritoneal sclerosis in rats

BACKGROUND

Peritoneal sclerosis (PS) is one of the most serious causes of failure in long-term peritoneal dialysis. Angiotensin II is known to promote fibrosis and inflammation in various tissues. We previously showed that ACE inhibitors (ACEIs) have beneficial effects on hypertonic PD solutions (3.86% PD) induced peritoneal alterations. The aim of this study is to compare the effects of an ACEI and a receptor blocker on peritoneal alterations induced by hypertonic PD solutions in rats.

METHODS

Forty-three non-uremic rats were divided into four groups: group I (Sham) rats received no treatment (n=11), group II received hypertonic (3.86%, 10 ml/day) PD solution (n = 10) and groups III and IV received hypertonic PD solution (10 ml/day) plus 640 mg/L valsartan (n=11) and 100 mg/L lisinopril in drinking water (n = 11). After four weeks, a one-hour peritoneal equilibration test (PET) was performed with 3.86% PD solution. Dialysate-to-plasma urea ratio (D/P urea), glucose reabsorption (D 1 /D 0 glucose), ultrafiltration volume (UF), dialysate protein, TGFbeta 1 and VEGF levels were determined.

RESULTS

Administration of valsartan or lisinopril resulted in preserved UF (8+/-0.8 and 6.7+/-0.7 vs 4.9+/-0.8 mL), D1/D0 glucose (0.69+/-0.05 and 0.62+/-0.05 vs 0.56+/-0.04) and peritoneal thickness (19.4+/-2.9 and 28.5+/-5.2 vs 53+/-3 microm), respectively. Both higher level of TGF beta 1 (206+/-40 vs 474+/-120 pg/mL, p<0.05), and VEGF in dialysate effluent (4+/-0.4 vs 7.9+/-3 pg/mL, p>0.05), was determined in the dextrose group. Both cytokines are partially inhibited by valsartan or lisinopril (p >0.05)

CONCLUSION

Exposure to hypertonic glucose solution resulted in alterations in peritoneal transport manifested by a rapid dissipation of the glucose gradient and resultant impaired UF response. Administration of valsartan or lisinopril led to attenuation of these alterations. We suggest that the equal protection of the peritoneal membrane from the effects of hypertonic glucose was achieved by receptor blockers and ACE inhibitors.

Diabetic nephropathy: the proteinuria hypothesis

BACKGROUND/AIMS

Proteinuria, nearly a universal finding in progressive kidney disease, has been the subject of frequent recent analyses in the renal literature. Proteinuria is a hallmark of diabetic nephropathy: microalbuminuria is the principal early predictor for progression of diabetic glomerulopathy, and proteinuria may be viewed as a measure of the severity and promoter of progression of nephropathy.

METHODS

This article critically reviews for the first time the full scope of diabetic proteinuria--complex molecular mechanisms, natural history, and analysis of treatment trials--in order to address the validity of 'the proteinuria hypothesis', i.e., that diabetic proteinuria is a modifiable determinant of renal progression. This hypothesis is analyzed in detail, including recent studies on the primary therapy of diabetic nephropathy, renin-angiotensin blockade.

RESULTS

As fully developed, this hypothesis consists of three postulates: that higher amounts of proteinuria predict progressive loss of function, that proteinuria reduction correlates with slowing progression, and that proteinuria is a surrogate endpoint for clinical trials. The latter postulate has not before been adequately linked to growing information about the first two postulates as they apply to diabetic kidney disease.

CONCLUSION

While diabetic nephropathy is a disease model for the potential use of proteinuria as a surrogate marker for renal progression, this shift in perspective will require prospective data from additional clinical trials, particularly of non-renin-angiotensin blocking drugs, to be complete.

Elevations in Serum Creatinine Concentration: Concerning or Reassuring?

The use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) has significantly reduced morbidity and mortality across the continuum of vascular disease. The utilization of these agents, however, remains suboptimal. The drugs are not prescribed in many patients because of concerns regarding their effects on renal function. Despite overwhelming evidence in favor of renoprotection, it is not uncommon for the glomerular filtration rate (GFR) to decrease shortly after starting treatment with an ACE inhibitor or ARB. This response is functional in nature and should be expected based on renal physiology and its dependence on the renin-angiotensin system to maintain GFR. Unfortunately, this phenomenon sometimes is viewed as an adverse effect or an indicator of underlying pathology. Although somewhat counterintuitive, early elevations in serum creatinine concentration are associated with improved long-term renal outcomes in patients with renal insufficiency and thus support, rather than condemn, continued treatment. Clinicians should be aware of the physiologic course associated with blockade of the renin-angiotensin system so that these agents will not be withheld unnecessarily.

Hypertension in people with Type 2 diabetes: knowledge-based diabetes-specific guidelines

The International Diabetes Federation (Europe) has updated these guidelines on hypertension management specifically in Type 2 diabetes in the light of recent results of the first prospective, randomized controlled studies to investigate clinical outcomes in people with diabetes and hypertension. The guidelines are knowledge based, i.e. based not only on evidence originating from clinical trials, but also from epidemiological and pathophysiological studies. A successful management strategy requires the following components: 1. Regular surveillance to detect developing hypertension and other cardiovascular (CV) risk factors. 2. Considering more frequent monitoring and review of CV risk factors if any single blood pressure (BP) measurement > 140/85 mmHg (or 130/75 if microalbuminuria); when appropriate, using ambulatory or home monitoring to establish the baseline BP. 3. Considering other CV risk factors, such as a raised albumin excretion rate, in setting the intervention threshold. 4. Individualizing the target BP in accordance with other CV risk factors. 5. Agreeing lifestyle and therapeutic interventions with the patient, with education and empowerment as required. 6. Implementing lifestyle modifications, including controlling calorie, salt and alcohol intake, increased physical activity, weight control and smoking cessation. 7. Therapeutic strategy: the primary goal of therapy is to reduce BP markedly. Combination therapy is often necessary, e.g. an angiotensin converting enzyme (ACE) inhibitor and a diuretic. Some classes are particularly useful for certain patients, notably longer-acting ACE inhibitors, angiotensin 2 receptor antagonists (A2RAs) and calcium antagonists in those at risk of diabetic nephropathy, loop diuretics and thiazides in those at risk of hyperkalaemia, beta-blockers and calcium antagonists (except short-acting dihydropyridines) in patients with angina, beta-blockers and ACE inhibitors after a myocardial infarction or in those with left ventricular dysfunction, and thiazide diuretics and long-acting dihydropyridine calcium antagonists for isolated systolic hypertension. A2RAs should be particularly considered when ACE inhibitors are not tolerated. alpha 1-Blockers should not be considered first line in the absence of outcome data. Cost of drugs will modify these strategies in developing countries. 8. Monitoring response to therapies and, if target levels are not achieved, either intensifying drug therapy if the CV risk justifies it, or reassessing the target. 9. Maintaining a quality assurance strategy. This strategy is summarized in a simple, practical management algorithm.

Design and statistical aspects of the African American Study of Kidney Disease and Hypertension (AASK)

The African American Study of Kidney Disease and Hypertension (AASK) is a multicenter randomized clinical trial designed to test the effectiveness of three anti-hypertensive drug regimens and two levels of BP control on the progression of hypertensive kidney disease. Participants include African-American men and women aged 18 to 70 yr who have hypertensive kidney disease and GFR between 20 and 65 ml/min per 1.73 m(2). The three anti-hypertensive drug regimens include an angiotensin converting enzyme inhibitor (ramipril), a dihydropyridine calcium channel blocker (amlodipine) or a beta-blocker (metoprolol) as initial therapy. The BP control levels are a lower goal (mean arterial pressure, Collapse

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MESH Headings

• Adolescent
• Adrenergic beta-Antagonists/administration & dosage
• Adult
• Black or African American/statistics & numerical data
• Aged
• Angiotensin-Converting Enzyme Inhibitors/administration & dosage
• Antihypertensive Agents/administration & dosage
• Calcium Channel Blockers/administration & dosage
• Dose-Response Relationship, Drug
• Drug Administration Schedule
• Drug Therapy, Combination
• Female
• Follow-Up Studies
• Humans
• Hypertension/complications
• Hypertension/diagnosis
• Hypertension/drug therapy
• Kidney Failure, Chronic/complications
• Kidney Failure, Chronic/diagnosis
• Kidney Failure, Chronic/therapy
• Male
• Middle Aged
• Pilot Projects
• Risk Assessment
• Treatment Outcome
• United States

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Grants

• U01 DK048643 NIDDK NIH HHS
• RR11145 NCRR NIH HHS
• U01 DK048648 NIDDK NIH HHS
• RR-00080 NCRR NIH HHS
• M01 RR000071 NCRR NIH HHS
• DK 2818 NIDDK NIH HHS
• M01 RR000052 NCRR NIH HHS
• M01 RR000032 NCRR NIH HHS
• K24 DK002818 NIDDK NIH HHS
• RR11104 NCRR NIH HHS
• RR-00071 NCRR NIH HHS
• P20 RR011104 NCRR NIH HHS
• P20 RR011145 NCRR NIH HHS
• U01 DK045381 NIDDK NIH HHS
• RR00827 NCRR NIH HHS
• U01 DK045386 NIDDK NIH HHS
• RR00052 NCRR NIH HHS
• M01 RR000827 NCRR NIH HHS
• M01 RR000080 NCRR NIH HHS
• RR00032 NCRR NIH HHS

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Affiliation(s)

Jennifer J Gassman Cleveland Clinic Department of Biostatistics, Ohio, 44195, USA.
Tom Greene
Jackson T Wright
Lawrence Agodoa
George Bakris
Gerald J Beck
Janice Douglas
Ken Jamerson
Julia Lewis
Michael Kutner
Otelio S Randall
Shin-Ru Wang

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Angiotensin II receptor antagonists and angiotensin-converting enzyme inhibitors lower in vitro the formation of advanced glycation end products: biochemical mechanisms

The implication of advanced glycation end products (AGE) in the pathogenesis of atherosclerosis and of diabetic and uremic complications has stimulated a search for AGE inhibitors. This study evaluates the AGE inhibitory potential of several well-tolerated hypotensive drugs. Olmesartan, an angiotensin II type 1 receptor (AIIR) antagonist, as well as temocaprilat, an angiotensin-converting enzyme (ACE) inhibitor, unlike nifedipine, a calcium blocker, inhibit in vitro the formation of two AGE, pentosidine and N(epsilon)-carboxymethyllysine (CML), during incubation of nonuremic diabetic, nondiabetic uremic, or diabetic uremic plasma or of BSA fortified with arabinose. This effect is shared by all tested AIIR antagonists and ACE inhibitors. On an equimolar basis, they are more efficient than aminoguanidine or pyridoxamine. Unlike the latter two compounds, they do not trap reactive carbonyl precursors for AGE, but impact on the production of reactive carbonyl precursors for AGE by chelating transition metals and inhibiting various oxidative steps, including carbon-centered and hydroxyl radicals, at both the pre- and post-Amadori steps. Their effect is paralleled by a lowered production of reactive carbonyl precursors. Finally, they do not bind pyridoxal, unlike aminoguanidine. Altogether, this study demonstrates for the first time that widely used hypotensive agents, AIIR antagonists and ACE inhibitors, significantly attenuate AGE production. This study provides a new framework for the assessment of families of AGE-lowering compounds according to their mechanisms of action.

Effect of ACE inhibitors in diabetic and nondiabetic chronic renal disease: a systematic overview of randomized placebo-controlled trials

Clinical trials have shown the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in delaying the progression of diabetic renal disease. There is less evidence from primary clinical trials of nondiabetic renal disease. We performed an updated meta-analysis to determine the efficacy of ACE inhibitors in slowing the progression of renal disease over a broad range of functional renal impairment. We included published and unpublished randomized, placebo-controlled, parallel trials with at least 1 year of follow-up available from January 1970 to June 1999. In nine trials of subjects with diabetic nephropathy and microalbuminuria, the relative risk for developing macroalbuminuria was 0.35 (95% confidence interval [CI], 0.24 to 0.53) for individuals treated with an ACE inhibitor compared with placebo. In seven trials of subjects with overt proteinuria and renal insufficiency from a variety of causes (30% diabetes, 70% nondiabetes), the relative risk for doubling of serum creatinine concentration or developing end-stage renal disease was 0.60 (95% CI, 0.49 to 0.73) for individuals treated with an ACE inhibitor compared with placebo. Treatment of individuals with chronic renal insufficiency with ACE inhibitors delays the progression of disease compared with placebo across a spectrum of disease causes and renal dysfunction.

Predictors of decreased renal function in patients with heart failure during angiotensin-converting enzyme inhibitor therapy: results from the studies of left ventricular dysfunction (SOLVD)

BACKGROUND

Although angiotensin-converting enzyme inhibitor therapy reduces mortality rates in patients with congestive heart failure (CHF), it may also cause decreased renal function. Little information is available to predict which patients are at highest risk for this complication.

OBJECTIVE

To quantify specific clinical predictors of reduction in renal function in patients with CHF who are prescribed angiotensin-converting enzyme inhibitor therapy.

METHOD

We analyzed data from the Studies of Left Ventricular Dysfunction (SOLVD), a randomized, double-blind, placebo-controlled trial of enalapril for the treatment of CHF. There were 3379 patients randomly assigned to enalapril with a median follow-up of 974 days and 3379 patients randomly assigned to placebo with a mean follow-up of 967 days. Decreased renal function was defined as a rise in serum creatinine >/=0.5 mg/dL (44 micromol/L) from baseline. We used time-to-event analysis to identify potential predictors of decrease in renal function including age, baseline ejection fraction, baseline creatinine, low systolic blood pressure (<100 mm Hg), history of hypertension, diabetes, and use of antiplatelet, diuretic, and beta-blocker therapy.

RESULTS

Patients randomly assigned to enalapril had a 33% greater likelihood of decreased renal function than controls (P =.003). By multivariate analysis, in both the placebo and enalapril groups older age, diuretic therapy, and diabetes were associated with decreased renal function, whereas beta-blocker therapy and higher ejection fraction were renoprotective. Older age was associated with a greater risk of developing decreased renal function in both groups, but significantly more so in the enalapril group (enalapril: risk ratio [RR] 1.42 per 10 years, 95% confidence interval [CI] 1.32-1.52 with enalapril; placebo: RR 1.18, 95% CI 1.12-1.25). Diuretic therapy was likewise associated with a greater risk of decreased renal function in the enalapril group (RR 1.89, 95% CI 1.70-2.08) than in the placebo group (RR 1.35, 95% CI 1.09-1.66). Conversely, enalapril had a relative renoprotective effect (RR 1.33, 95% CI 1.13-1.53) compared with placebo (RR 1.96, 95% CI 1.57-2.44) in patients with diabetes. A lower risk of renal impairment was seen in both groups with beta-blocker therapy (RR 0.70, 95% CI 0.57-0.85) and higher baseline ejection fraction (RR 0.93 per 5% increment, 95% CI 0.91-0. 96).

CONCLUSIONS

Enalapril use caused a 33% increase in the risk of decreased renal function in patients with CHF. Diuretic use and advanced age increased this risk. Diabetes was associated with an increased risk of renal impairment in all patients with CHF, but this risk was reduced in the enalapril group compared with the placebo group. beta-Blocker therapy and higher ejection fraction were renoprotective in all patients regardless of therapy.

Pharmacological treatment of diabetic patients with cardiovascular complications

Cardiovascular complications are frequently present in insulin-dependent (IDDM) and non-insulin dependent diabetes mellitus (NIDDM) patients and confer a very poor prognosis. In this overview we critically analyse the current literature with regard to the benefits and also the possible harms of the available pharmacological treatment strategies in these patients. To date, insulin is the only hypoglycaemic agent which has been proven both effective and safe in NIDDM patients with cardiovascular complications. Also, several trials indicate that treatment with oral hypoglycaemic agents may confer a substantial risk in such patients. Conventional antihypertensive treatment, including betablockers and diuretics, has been convincingly shown to reduce mortality and morbidity in diabetic nephropathy and in NIDDM patients. However, this may not be the case with newer antihypertensive agents, such as angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers. Likewise, convincing evidence is lacking that these newer antihypertensive agents provide meaningful clinical benefit when compared to the conventional treatment regarding slower progression of diabetic nephropathy or their impact on lipid and glucose metabolism. Cholesterol lowering therapy with statins and aspirin treatment have also been repeatedly shown to improve the prognosis of diabetic patients with coronary heart disease.

Interactions of transforming growth factor-beta and angiotensin II in renal fibrosis

Overproduction of transforming growth factor-beta clearly underlies tissue fibrosis in numerous experimental and human diseases. Transforming growth factor-beta's powerful fibrogenic action results from simultaneous stimulation of matrix protein synthesis, inhibition of matrix degradation, and enhanced integrin expression that facilitates matrix assembly. In animals, overexpression of transforming growth factor-beta by intravenous injection, transient gene transfer, or transgene insertion has shown that the kidney is highly susceptible to rapid fibrosis. The same seems true in human disease, where excessive transforming growth factor-beta has been demonstrated in glomerulonephritis, diabetic nephropathy, and hypertensive glomerular injury. A possible explanation for the kidney's particular susceptibility to fibrosis may be the recent discovery of biologically complex interactions between the renin-angiotensin system and transforming growth factor-beta. Alterations in glomerular hemodynamics can activate both the renin-angiotensin system and transforming growth factor-beta. Components of the renin-angiotensin system act to further stimulate production of transforming growth factor-beta and plasminogen activator inhibitor leading to rapid matrix accumulation. In volume depletion, transforming growth factor-beta is released from juxtaglomerular cells and may act synergistically with angiotensin II to accentuate vasoconstriction and acute renal failure. Interaction of the renin-angiotensin system and transforming growth factor-beta has important clinical implications. The protective effect of inhibition of the renin-angiotensin system in experimental and human kidney diseases correlates closely with the suppression of transforming growth factor-beta production. This suggests that transforming growth factor-beta, in addition to blood pressure, should be a therapeutic target. Higher doses or different combinations of drugs that block the renin-angiotensin system or entirely new drug strategies may be needed to achieve a greater antifibrotic effect.

Current clinical pathophysiologic considerations in essential hypertension

Over the years, much has been learned from unraveling the pathophysiological alterations associated with the hypertensive diseases. Despite this large base of fundamental and clinical information, our knowledge continues to expand. This article discusses the multifactorial nature of hypertensive disease, including the vascular and cardiac participation in the elevation of arterial pressure and in target organ involvement by the disease. Some of the most exciting advances of the last decade are summarized in this review.

Differential efficacy of perindopril and enalapril in experimental diabetic nephropathy

1. Treatment with angiotensin converting enzyme (ACE) inhibitors ameliorates human and experimental diabetic nephropathy, possibly as a result of changes in angiotensin II (AngII) and/or bradykinin concentrations. However, ACE is an indiscriminate enzyme, which hydrolyses numerous vasoactive peptides at two catalytic sites that are thought to be substrate specific. AngI is cleaved at the C-terminal site, bradykinin at both the C- and N-terminal sites, while other substrates may be preferentially cleaved at the N-terminal site. Of the various ACE inhibitors, some (e.g. perindopril) bind preferentially to the C-terminal site while others (e.g. enalapril) bind to both. We compared the efficacy of perindopril and enalapril in the diabetic SHR to determine whether all the benefits of ACE inhibition derive from changes in the concentrations of C-terminal related substrates. 2. Diabetes was induced by tail vein injection of streptozotocin (60 mg/kg) in 14 week old SHR. Blood glucose was maintained at 4-8 mmol/L by daily ultralente insulin injection and rats were randomized to control, enalapril (10 mg/kg per day) or perindopril (4 mg/kg per day) groups. Blood pressure, creatinine clearance and urinary protein excretion were monitored for 3 months. 3. Blood pressure in both treatment groups was lower than in control (perindopril P < 0.0001; enalapril P < 0.0001). Levels were marginally higher in the perindopril group than the enalapril group, although this difference was significant only in the second month (P < 0.025). Creatinine clearance was significantly lower in the perindopril group (0.44 +/- 0.05 mL/min) than in either the control rats (0.85 +/- 0.11 mL/min; P < 0.001) or the enalapril-treated group (0.66 +/- 0.05 mL/min; P < 0.005). Proteinuria was also lower in this group (4.3 +/- 0.9 mg/24h) than in the enalapril-treated (11.3 +/- 5.8 mg/24h; P < 0.05) or control groups (32.1 +/- 4.5 mg/24h; P < 0.0005). 4. The difference in efficacy between perindopril and enalapril that we have observed suggests that the benefits of ACE inhibition derive from changes in the concentrations of peptides catalysed by the C-terminal rather than the N-terminal site.

Prevention and Treatment of Diabetic Nephropathy: Role of Angiotensin-Converting Enzyme Inhibitors

OBJECTIVE

To discuss the role of angiotensin-converting enzyme inhibitors in the management of diabetes-related renal disease.

METHODS

We review the published data from animal studies and clinical trials and outline the adverse effects that may limit the use of these drugs.

RESULTS

Diabetic nephropathy is the most common cause of end-stage renal disease and dialysis in the United States. With improving measures to optimize blood glucose control and blood pressure, the progression from mild proteinuria to overt renal insufficiency can now be retarded or even arrested. Studies of therapeutic interventions have shown that angiotensin-converting enzyme inhibitors have a superior beneficial effect on nephropathy. Few adverse effects are associated with use of these drugs: a nonproductive cough is the most frequent side effect, and angioedema and agranulocytosis are the most serious (albeit rarely reported) effects.

CONCLUSION

Angiotensin-converting enzyme inhibitors should be considered as first-line therapy for patients with diabetes who have microalbuminuria or macroalbuminuria.

Diabetic renal disease: the quest for normotension--and beyond

Over the past two decades there has been an increasing interest in hypertension as a risk factor for diabetic renal disease and in particular for the possibility of early antihypertensive intervention. Therefore, it would seem timely to review the history of hypertension in diabetes, with special reference to renal disease and the need for normotension, in a manner resembling glycaemic control. Elevated blood pressure (BP) associated with diabetes mellitus has been recognized since the beginning of the century and was initially particularly documented in association with the demonstration of the striking histological lesion in glomeruli, starting with the observation of Kimmelstiel and Wilson in 1936. These patients in many cases also showed hypertension, as confirmed in several subsequent reports, very similar to the studies of Kimmelstiel and Wilson. However, the development was hampered by the lack of effective antihypertensive agents and also by some who believed that elevated BP could be of importance to preserve renal function in these individuals. Indeed, it was suggested that reduction of BP could mean permanent deterioration in renal function. BP remained very high in the standard care of diabetic patients up to the middle 1970s. At this time it was documented that elevated BP was very closely related to development of diabetic renal disease in Type 1 (insulin-dependent) diabetic (IDDM) patients, and studies also showed a correlation between blood pressure and rate of progression. This correlation stimulated research in intervention, and indeed in the 1980s and 1990s several long-term studies reported that antihypertensive treatment can reduce the rate of decline in glomerular filtration rate (GFR) from about 12 ml min-1 yr-1 down to about 2 ml min-1 yr-1 in the most optimistic reports; usually a mean level of 2-5 ml min-1 yr-1 is achievable by antihypertensive treatment, in clinical situations where glycaemic control often is far from perfect. Many studies have also documented that BP starts to rise in the early phase of incipient diabetic nephropathy characterized by microalbuminuria. This is a stage with well-preserved GFR and therefore probably an ideal stage for intervention in these at risk patients. Many studies, in particular those employing angiotensin converting enzyme (ACE) inhibitors based on important pathophysiological concepts proposed by Brenner, have shown that microalbuminuria can be reduced or stabilized by early antihypertensive treatment, just as we see with optimized glycaemic control. ACE inhibitors have also been widely used in patients with overt nephropathy and the rate of decline in GFR has been reduced considerably.(ABSTRACT TRUNCATED AT 400 WORDS)

Selected aspects of ACE inhibitor therapy for patients with renal disease: impact on proteinuria, lipids and potassium

Overt proteinuria is often accompanied by hypercholesterolemia and is associated with increased lipoprotein(a) levels. These lipid abnormalities are probably involved in the high incidence of macrovascular complications associated with diabetic nephropathy and possibly other kinds of non-diabetic proteinuric renal disease. Over the last decade many studies have shown that ACE inhibitors can reduce urinary protein excretion but little attention was paid to the impact of this form of therapeutic intervention on the lipid profile. In this article we review our recent data showing that fosinopril administration was associated with significant decreases in both urinary protein excretion, serum total cholesterol levels, and plasma lp(a) levels. The use of ACE inhibitors in patients with renal impairment can result in the development of hyperkalemia as a result of suppression of angiotensin II-driven aldosterone secretion by the adrenal gland. Inhibition of aldosterone secretion may depend on the degree of inhibition of angiotensin II formation in the circulation and also locally in the adrenal gland. Because the various ACE inhibitors exhibit different degrees of ACE inhibition at the tissue level, we have postulated that angiotensin II-dependent aldosterone production will be inhibited to a lesser degree by agents that have low tissue affinity for the adrenal gland. The implication of this theoretical concept for the development of hyperkalemia in patients with impaired renal function treated with ACE inhibitors is discussed.

Contrasting effects of angiotensin converting inhibitor and alpha-1-antagonist on albuminuria in insulin-dependent diabetes mellitus patients with nephropathy

OBJECTIVE

The main aim of this study was to examine the effects of an angiotensin converting inhibitor, enalapril, and an alpha-1 (alpha-1) antagonist, doxazosin, on albumin excretion, renal haemodynamics and tubular function in insulin-dependent diabetes mellitus patients with nephropathy.

DESIGN

The study consisted of a four-week run-in period, a four-week active treatment period, a four-week wash-out period and a second four-week active treatment period.

SETTING

The study was performed in the out-patient clinic at a university hospital.

SUBJECTS

Ten patients with insulin dependent diabetes mellitus with macroalbuminuria (> 200 micrograms min-1), mild to moderate hypertension (diastolic blood pressure 85-115 mmHg) and serum creatinine level below 200 mumol L-1 were included in the study.

MAIN OUTCOME MEASURES

The effect of the drugs on albumin and total protein excretion, beta-2-microglobulin, proximal tubular enzyme markers and renal haemodynamics.

RESULTS

Systolic and diastolic blood pressure were equally reduced by both drugs. Enalapril reduced albumin excretion from 1090 +/- 281 micrograms min-1 to 742 +/- 246 micrograms min-1 (P < 0.01) and total protein excretion from 2.0 +/- 0.4 g per 24 h to 1.3 +/- 0.4 per 24 h whereas doxazosin was without effect. Glomerular filtration rate and effective renal plasma flow were unchanged by either drug. Doxazosin increased filtration fraction from 0.21 +/- 0.02 to 0.23 +/- 0.01 (P < 0.05). The urinary excretion of the proximal enzyme markers N-acetyl-beta-glucosaminidase and alkaline phosphatase were elevated as well as urinary excretion of beta-2-microglobulin. However, neither the excretion of beta-2-microglobulin nor the enzyme markers were affected by either drug.

CONCLUSIONS

Enalapril, but not doxazosin, reduces albuminuria in insulin dependent diabetes mellitus patients with nephropathy. The drugs exert differential effects on renal haemodynamics.

The paradox of the renin-angiotensin system in chronic renal disease

Despite normal to suppressed levels of renin activity in chronic renal disease, multiple lines of evidence suggest a role for the RAS, especially its intrarenal expression, in several critical aspects of this condition. Alterations in the distribution and control of components of the renal RAS could account for localized areas of activation of this system. Renal scarring may be particularly important as a major stimulus to renin synthesis in the diseased kidney. While both intrarenal and systemic hypertension may depend in part upon actions of the RAS, other non-hemodynamic actions of the RAS may also contribute to the adaptation of residual nephrons as well as their progressive injury.

Low-protein diets and angiotensin-converting enzyme inhibition in progressive renal failure

Both protein restriction and administration of angiotensin-converting enzyme (ACE) inhibitors have been reported to slow the progression of chronic renal failure. Protein intake conditions the activity of the renin-angiotensin system and the renal production and excretion in the urine of eicosanoids. Both dietary protein restriction and ACE inhibitors decrease proteinuria. The effects of ACE inhibitors on the progression of renal disease may be due to hemodynamic effects (lowering of systemic or intraglomerular pressures) or to decreased activity of growth factors as a result of blockade or angiotensin II production.