Pretreatment blood pressure reliably predicts progression of chronic nephropathies. GISEN Group

Progression of renal disease: renoprotective specificity of renin-angiotensin system blockade

Recent guidelines for management of patients with chronic kidney disease recommend both lower optimal BP targets and agents that block the renin-angiotensin system (RAS) for specific additional BP-independent renoprotection. Although there are other compelling rationales to use RAS blockade in patients with chronic kidney disease, including its antihypertensive effectiveness and ability to counteract the adverse effects of diuretics, a critical review of the available scientific evidence suggests that the specificity of renoprotection that is provided by RAS blockade has been greatly overemphasized. Little evidence of truly BP-independent renoprotection is observed in experimental animal models when ambient BP is assessed adequately by chronic continuous BP radiotelemetry. Although the clinical trial evidence is somewhat stronger, nevertheless, even when interpreted favorably, the absolute magnitude of the BP-independent component of the renoprotection that is observed with RAS blockade is much smaller than what is due to its antihypertensive effects.

Angiotensin-converting enzyme inhibition and renal protection in nondiabetic patients: the data of the meta-analyses

ESRD represents a major health problem. The number of patients who enter kidney replacement programs has increased at an average of 7% per year in the past 10 yr. A large number of experimental and clinical studies have demonstrated that chronic nephropathies share common pathogenic mechanisms that contribute to renal disease progression, even independent of the original cause. Clinical studies found a significant correlation between the extent of urinary protein excretion and the rate of GFR decline in both diabetic and nondiabetic chronic nephropathies. Randomized trials, in particular the Ramipril Efficacy In Nephropathy (REIN) study, also showed that treatments that reduce proteinuria (namely angiotensin-converting enzyme [ACE] inhibitors) are renoprotective and limit progression to ESRD. Meta-analyses of randomized clinical trials also evaluated the role of proteinuria and of ACE inhibition therapy in chronic renal disease progression. Their findings were consistent with those of the REIN study and confirmed in larger series of patients the predictive value of proteinuria and the renoprotective effect of proteinuria reduction by ACE inhibition therapy. Thus, the meta-analyses may confirm and extend previous findings generated by randomized clinical trials. Conceivably, well-designed studies in properly selected and carefully monitored patients who are at increased risk continue to be the best approach to test novel hypotheses. The meta-analyses, however, represent a valuable tool to evaluate the consistency and generalizability of trial results to larger cohorts of patients.

Risk factors for renal failure in children with non-glomerular nephropathies

The aim of the present study was to analyze the progression of chronic renal failure (CRF), the effects of modification of risk factors for disease progression, and to formulate a theoretical model of CRF progression in an unselected group of children with CRF. The study was a cross-sectional, retrospective analysis of 92 patients aged 9.2+/-5.8 years with CRF and low-level proteinuria [glomerular filtration rate (GFR) 43+/-18 ml/min per 1.73 m(2), proteinuria 0.57 g/day, range 0-3.9 g/day]. Inclusion criteria were an established diagnosis of CRF and completion of any surgical treatment. The etiology of CRF in the majority of patients was congenital uropathy. Sixty-nine patients observed for longer than 3 years were divided into two groups according to progression of CRF or improvement of GFR. Forty-three patients were on renoprotective therapy. Over a 3-year period GFR decreased in 39 children and improved in 30 children. There were no differences between the groups in the etiology of CRF. Patients with progression of CRF were older ( P<0.08), grew faster ( P<0.004), had higher blood pressure ( P<0.01), and were more often proteinuric ( P<0.03). Arterial hypertension in patients with progression of CRF was resistant to therapy and these patients needed more intensive treatment. Renoprotective therapy led to improvement of kidney function in 50% of patients, and resistance to renoprotective therapy was correlated with increased body mass and height. Patients who received renoprotective drugs showed stabilized kidney function ( P<0.007) and decreased proteinuria ( P<0.05) and blood pressure ( P<0.02), despite higher basal values. In patients on renoprotective therapy in whom CRF progressed despite treatment, proteinuria was persistent in contrast to patients with improvement ( P<0.02). The best model of CRF progression in the path diagram included systolic blood pressure and anthropometric parameters. In conclusion, in unselected patients with CRF of non-glomerular origin and nil-to-moderate proteinuria the main risk factors for CRF progression are rapid somatic growth, age, and blood pressure. Arterial hypertension and proteinuria, even of mild intensity, differ significantly between patients with progression of CRF and those with stable or improved renal function. Renoprotective therapy is related to significant slowing of CRF progression, but the risk factors for resistance to therapy include persistent proteinuria and somatic growth.

Blood pressure and long-term mortality in United States hemodialysis patients: USRDS Waves 3 and 4 Study

BACKGROUND

The long-term prognostic associations of pre- and post-dialysis blood pressures, interdialytic weight gain, and antihypertensive use in hemodialysis patients are unclear.

METHODS

The United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Waves 3 and 4 Study, a randomly generated sample of 11,142 subjects receiving hemodialysis on December 31, 1993, was examined, with vital status followed until May 2000.

RESULTS

Pre- and post-dialysis blood pressure values, interdialytic weight gain and number of antihypertensives averaged 151.8/79.7, 137.0/74, 3.6% and 0.76, respectively. Prognostic discrimination was maximized by considering pre- and post-systolic and diastolic blood pressure values simultaneously, in a pattern suggesting that wide pulse pressures were associated with mortality (P < 0.0001). Comorbidity adjustment markedly affected associations, with low pre-dialysis diastolic (P < 0.05), low post-dialysis dialysis diastolic pressure (P < 0.05), high post-dialysis dialysis systolic pressure (P < 0.05), and high interdialytic weight gains (P = 0.005) associated with mortality. Each class of antihypertensive drug, except angiotensin-converting enzyme (ACE)-inhibitors, was associated with lower mortality in unadjusted models, an effect most pronounced for beta-blockers (hazards ratio 0.72, 95% CI 0.66 to 0.79, P < 0.0001). Comorbidity adjustment eliminated survival associations for each antihypertensive class except beta-blockers.

CONCLUSIONS

Pre- and post-dialysis blood pressure values have independent associations with mortality, in a way that implicates wide pulse pressures. Much of the adverse prognosis of wide pulse pressures probably reflects older age and cardiovascular comorbidity. Large interdialytic weight gains are associated with shorter survival when comorbidity is taken into account. Beta-blocker use shows a robust association with survival, and may be protective.

Long-term renal consequences of hypertension for normal and diseased kidneys

Substantial evidence indicates that the adverse effects of hypertension on the kidney depend on the degree to which systemic blood pressure elevations are transmitted to the renal microvasculature. Such blood pressure transmission and consequent susceptibility to hypertensive renal damage is markedly exacerbated in states characterized by preglomerular vasodilation and an impairment of the normally protective renal autoregulatory mechanisms, e.g. diabetes or chronic renal disease. Moreover, this pathophysiology gives rise to the prediction that prevention of hypertension-induced barotrauma will require blood pressure to be reduced well into the normotensive range in such patients, as is being recognized in the currently recommended blood pressure goals. Agents that block the renin-angiotensin system should be preferred as initial therapy as they may provide additional risk reductions and minimize the potassium and magnesium depletion associated with the diuretic use usually necessary to achieve the lower blood pressure targets. The current failure to achieve optimal blood pressure reductions may be contributing not only to the still escalating incidence of end-stage renal disease in diabetic patients, but also to their greatly increased cardiovascular morbidity and mortality.

Progression, remission, regression of chronic renal diseases

The prevalence of chronic renal disease is increasing worldwide. Most chronic nephropathies lack a specific treatment and progress relentlessly to end-stage renal disease. However, research in animals and people has helped our understanding of the mechanisms of this progression and has indicated possible preventive methods. The notion of renoprotection is developing into a combined approach to renal diseases, the main measures being pharmacological control of blood pressure and reduction of proteinuria. Lowering of blood lipids, smoking cessation, and tight glucose control for diabetes also form part of the multimodal protocol for management of renal patients. With available treatments, dialysis can be postponed for many patients with chronic nephropathies, but the real goal has to be less dialysis-in other words remission of disease and regression of structural damage to the kidney. Experimental and clinical data lend support to the notion that less dialysis (and maybe none for some patients) is at least possible.