IgA nephropathy and inhibitors of the renin angiotensin system: is reduction in proteinuria adequate proof of efficacy?

Effect of Dual Blockade of Renin-Angiotensin System on Proteinuria

Aim: Aim of the study was the evaluation of the effect of dual blockade of the renin-angiotensin system (RAS) on proteinuria. Material and Methods: Sixty patients, included in the study, were treated with angiotensin-converting enzyme inhibitor and angiotensin receptor blocker for a period of 3 months. Results: The dual blockade of RAS resulted with decrease of proteinuria, a slight increase of serum creatinine and was not associated with a lowering of blood pressure.Conclusion: Combined therapy with ACE-I and ARB results in a more complete blockade of the RAS than monotherapy. In proteinuric nephropathies it reduces significantly baseline proteinuria.

Combination Angiotensin-Converting Enzyme Inhibitor and Angiotensin Receptor Blocker Therapy: Its Role in Clinical Practice

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are commonly prescribed for the management of hypertension. In addition, each of these drug classes has been shown to be effective in the treatment of congestive heart failure, proteinuric chronic kidney disease, and most recently the high-cardiac-risk profile patient. The individual success of each of these drug classes has fueled the theory that given together, the overall biologic effect of both would surpass that of either given alone. The foundation of this premise, although biologically plausible, has yet to be proven in a compelling enough fashion to support the everyday use of these two drug classes in combination. Additional clarifying studies are required to establish whether specific patient subsets exist that might benefit from such combination therapy.

IgACE: A Placebo-Controlled, Randomized Trial of Angiotensin-Converting Enzyme Inhibitors in Children and Young People with IgA Nephropathy and Moderate Proteinuria

This European Community Biomedicine and Health Research-supported, multicenter, randomized, placebo-controlled, double-blind trial investigated the effect of an angiotensin-converting enzyme inhibitor (ACE-I) in children and young people with IgA nephropathy (IgAN), moderate proteinuria (>1 and <3.5 g/d per 1.73 m(2)) and creatinine clearance (CrCl) >50 ml/min per 1.73 m(2). Sixty-six patients who were 20.5 yr of age (range 9 to 35 yr), were randomly assigned to Benazepril 0.2 mg/kg per d (ACE-I) or placebo and were followed for a median of 38 mo. The primary outcome was the progression of kidney disease, defined as >30% decrease of CrCl; secondary outcomes were (1) a composite end point of >30% decrease of CrCl or worsening of proteinuria until > or =3.5 g/d per 1.73 m(2) and (2) proteinuria partial remission (<0.5 g/d per 1.73 m(2)) or total remission (<160 mg/d per 1.73 m(2)) for >6 mo. Analysis was by intention to treat. A single patient (3.1%) in the ACE-I group and five (14.7%) in the placebo group showed a worsening of CrCl >30%. The composite end point of >30% decrease of CrCl or worsening of proteinuria until nephrotic range was reached by one (3.1%) of 32 patients in the ACE-I group, and nine (26.5%) of 34 in the placebo group; the difference was significant (log-rank P = 0.035). A stable, partial remission of proteinuria was observed in 13 (40.6%) of 32 patients in the ACE-I group versus three (8.8%) of 34 in the placebo group (log-rank P = 0.033), with total remission in 12.5% of ACE-I-treated patients and in none in the placebo group (log-rank P = 0.029). The multivariate Cox analysis showed that treatment with ACE-I was the independent predictor of prognosis; no influence on the composite end point was found for gender, age, baseline CrCl, systolic or diastolic BP, mean arterial pressure, or proteinuria.

Combination ACE Inhibitor and Angiotensin Receptor Blocker Therapy-Future Considerations

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are regularly prescribed for the management of hypertension. Each of these drug classes has also been shown to provide survival benefits for patients with heart failure, proteinuric chronic kidney disease, and/or a high cardiac risk profile. The individual gains seen with each of these drug classes have led to speculation that their combination might offer additive if not synergistic outcome benefits. The foundation of this hypothesis, although biologically possible, has thus far not been sufficiently well proven to support the everyday use of these 2 drug classes in combination. Additional outcomes trials, which are currently proceeding to their conclusion, may provide the necessary proof to support an expanded use of these 2 drug classes in combination.

Effect of microalbuminuria lowering on regression of left ventricular hypertrophy in children and adolescents with essential hypertension

Microalbuminuria (MA) is associated with increased cardiovascular risk in adult hypertensive patients, but no study has specifically examined the effects of MA lowering on regression of left ventricular hypertrophy (LVH) among pediatric patients with hypertension. Fifty-five patients with essential hypertension, 11-19 years old, were prospectively studied. All patients received concomitant therapy of hydrochlorothiazide and angiotensin-converting enzyme inhibitor. Five patients also required angiotensin receptor blocker to achieve the blood pressure goal. Baseline and 12-month follow-up measures of left ventricular mass index (LVMI), determined by echocardiography and urine microalbumin/creatinine ratio (MA/Cr), were collected. MA was defined as MA/Cr >30 microg/mg. LVH was defined as LVMI >38.6 g/m(2.7). The primary end points were reductions in MA and LVMI of 25% or more. Weight (r = 0.83), body surface area (r = 0.85), body mass index (BMI) (r = 0.86), systolic blood pressure (SBP) (r = 0.57), diastolic blood pressure (DBF) (r = 0.49), mean arterial pressure (r = 0.53) and MA (r= 0.87) were all univariate correlates of LVMI. In a multiple regression analysis, MA, BMI and SBP were significant correlates of LVMI. MA alone explained 76% of the variance of LVMI, whereas BMI and SBP explained only 1.6 and 0.4% of the variance, respectively. MA was the most significant correlate of follow-up LVMI after BMI and SBP were included in the overall multiple regression models. Thus, MA is a strong predictor of LVH in hypertensive children and adolescents. MA lowering halts the progression of LVH or induces its regression.

Hong Kong study using valsartan in IgA nephropathy (HKVIN): a double-blind, randomized, placebo-controlled study

BACKGROUND

Previous studies showed that angiotensin-receptor blocker (ARB) therapy decreased proteinuria and possibly slowed the rate of renal function decline in patients with chronic proteinuric nephropathies. We performed a double-blind, randomized, placebo-controlled, multicenter study on the ARB valsartan in the treatment of patients with immunoglobulin A (IgA) nephropathy.

METHODS

From 6 centers, we recruited 109 patients with IgA nephropathy who had either: (1) proteinuria with protein greater than 1 g/d and serum creatinine level less than 2.8 mg/dL (< 250 micromol/L), or (2) serum creatinine level of 1.4 to 2.8 mg/dL (120 to 250 micromol/L) regardless of degree of proteinuria. Patients were randomly assigned to administration of either valsartan, 80 mg/d (titrated up to 160 mg/d for blood pressure control), or placebo for 104 weeks. Additional antihypertensive therapy was allowed to achieve a target blood pressure of 140/90 mm Hg. The primary end point was doubling of serum creatinine level or dialysis-dependent renal failure. Secondary outcomes included change in proteinuria and decrease in glomerular filtration rate (GFR).

RESULTS

There were 54 patients in the treatment group and 55 patients in the placebo group. Baseline clinical characteristics were similar between groups, although the treatment group had a marginally greater baseline GFR (87 +/- 36 versus 78 +/- 38 mL/min/1.73 m2 [1.45 +/- 0.60 versus 1.30 +/- 0.63 mL/s/1.73 m2];P = 0.29) and less proteinuria (protein, 1.8 +/- 1.2 versus 2.3 +/- 1.7 g/d; P = 0.21) than the placebo group. Average blood pressures during the study were 92.7 +/- 10.6 mm Hg in the treatment group and 100.9 +/- 9.1 mm Hg in the placebo group (P < 0.001). During the study period, 4 patients in the placebo group and 1 patient in the treatment group reached the primary end point (log-rank test, P = 0.18). Proteinuria decreased significantly in the treatment group (protein, 1.8 +/- 1.2 to 1.2 +/- 1.2 g/d; P = 0.03), but did not change in the placebo group. With multiple linear regression models, valsartan treatment resulted in a 33.0% decrease in proteinuria (95% confidence interval, 10.9 to 55.1) after adjusting for other confounding factors. There was a significant decrease in mean rate of GFR decrease in the valsartan-treated group (-5.62 +/- 6.79 mL/min/y [-0.09 +/- 0.11 mL/s/y]) compared with the placebo group (-6.98 +/- 6.17 mL/min/y [-0.12 +/- 0.10 mL/s/y]) throughout the study period after adjustment for average blood pressure and proteinuria (P = 0.014).

CONCLUSION

Valsartan significantly decreases proteinuria and slows renal deterioration in patients with IgA nephropathy after adjustment for confounding factors, notably blood pressure. The long-term benefit of valsartan needs to be confirmed with additional studies.

Value of urinary excretion of microalbumin in predicting glomerular lesions in children with isolated microscopic hematuria

Urinary microalbumin excretion was assessed in 76 children with asymptomatic microscopic hematuria in whom the presence of proteinuria, hypertension, reduced renal function, hypercalciuria, urinary tract infection or structural abnormality of the urinary tract had been excluded. All children underwent a percutaneous kidney biopsy to determine whether microalbumin excretion can be used as a marker to predict the source of hematuria. Microalbumin excretion was considered normal if the urinary ratio of microalbumin to creatinine (MA/Cr ug/mg) was < or =30. Twenty-two (29%) had microalbuminuria (MA/Cr 96+/-30 microg/mg) and 54 (71%) had normal albumin excretion (MA/Cr 13+/-2 microg/mg). Of those with normoalbuminuria, 38 (70%) had normal renal tissue, 15 (28%) thin glomerular basement membrane (TGBM) disease and 1 (2%) IgA nephropathy. In contrast, 20 (91%) of those with microalbuminuria had IgA nephropathy and 2 (9%) had TGBM disease. The mean urinary MA/Cr ratio for all IgA children was 89+/-32 microg/mg higher compared with a value for the children with TGBM disease (14 +/-3 microg/mg, P <0.001) or children whose renal biopsy appeared normal (11+/-2 microg/mg, P <0.001). Statistical analysis revealed no significant differences between the mean MA/Cr ug/mg ratio for children with TGBM disease and those with normal glomerular findings. Fourteen of the 20 children with IgA nephropathy who also had microalbuminuria were treated with an angiotensin-converting enzyme (ACE) inhibitor. Over a mean follow-up of 51 months, none developed overt proteinuia; hematuria resolved and microalbuminuria returned to normal in eight (57%) during therapy with the ACE-inhibitor. In contrast, hematuria persisted and prtoteinuria developed in the other untreated children. None of the children with TGBM disease developed overt proteinuria after a mean of 51 months. Hematuria was persistent in children with TGBM disease, but often resolved in those whose biopsies were completely normal. These data suggest that determination of urinary microalbumin excretion is warranted in the routine examination of children with isolated microscopic hematuria. Routine screening for microalbuminuria may help to identify a subgroup of patients with IgA nephropathy who are at high risk for progressive kidney disease and need more intensive therapy and closer follow-up.

The practical aspects of combination therapy with angiotensin receptor blockers and angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers (ARBs) are widely prescribed for the management of hypertension. ACE inhibitors (ACE-I) and, more recently, ARBs have an established track record of success in the treatment of congestive heart failure (CHF), proteinuric renal disease and most recently the hypertensive patient with a high cardiac-risk profile. The individual success of each of these drug classes has fuelled speculation that given together the overall effect of both would exceed that of either given alone. This premise, although biologically plausible, has yet to be proven in a convincing enough fashion to support the routine use of these two drug classes in combination. Additional clarifying studies are needed to establish whether specific patient subsets exist that might benefit from such combination therapy.

Type 2 diabetes: RENAAL and IDNT--the emergence of new treatment options

The Reduction in End Points in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study and the Irbesartan Diabetic Nephropathy Trial (IDNT) are two recently reported trials with hard end points, conducted in patients in advanced stages of diabetic nephropathy. Two other studies--the Irbesartan Microalbuminuria Study (IRMA)-2 and the Microalbuminuria Reduction with Valsartan study (MARVAL)--were trials conducted in patients with type 2 diabetes with microalbuminuria, a cardiovascular risk factor associated with early-stage diabetic nephropathy. These trials all had a common theme--that is, does an angiotensin receptor blocker (ARB) interfere with the natural history of diabetic nephropathy in a blood pressure-independent fashion? Without question, the results of these trials legitimatize the use of the ARB class in forestalling the deterioration in renal function, which is almost inevitable in the patient with untreated diabetic nephropathy. These data can now be added to the vast array of evidence supporting angiotensin-converting enzyme (ACE) inhibitor use in patients with nephropathy associated with type 1 diabetes. It now appears a safe conclusion that the patient with diabetic nephropathy should receive therapy with an agent that interrupts the renin-angiotensin system. These studies have not resolved the question as to whether an ACE inhibitor or an ARB is the preferred agent in people with nephropathy from type 1 diabetes, though the optimal doses of these drugs remain to be determined. Head-to-head studies comparing ACE inhibitors to ARBs in diabetic nephropathy are not likely to occur, so it is unlikely that comparable information will be forthcoming with ACE inhibitors. An evidence-based therapeutic approach derived from these trials would argue for ARBs to be the foundation of therapy in the patient with type 2 diabetes and nephropathy.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in combination: theory and practice

Angiotensin converting enzyme inhibitors and angiotensin receptor blockers are commonly used to treat hypertension and/or a range of progressive end-organ diseases. The success of each of these drug classes in disease-state management is without dispute, and has led to speculation that given together the observed response would improve upon that observed with a member of each drug class individually given. Few studies are available, however, which carefully address the effect(s) of the combination of an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker. Review of available studies would seem not to strongly support combination therapy with an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker as preferred therapy in the broad base of general hypertensive patients with or without end-organ disease. Additional clarifying studies are needed to determine if specific patient subsets exist that might benefit from such combination therapy.