Toto RD, Mitchell HC, Smith RD, Lee H-C, McIntire D,
Pettinger WA
"Strict" blood pressure control and progression of renal
disease in hypertensive nephrosclerosis
Kidney Int
(Sep) 48:851-859 1995
Hypertensive nephrosclerosis is the leading cause of ESRD in
African-Americans in the United States. Most of the patients with this
diagnosis have not undergone renal biopsy, but recent studies suggest
that clinical data are highly predictive of hypertension. Theoretically
renal damage caused by systemic hypertension should be mitigated or
abolished if blood pressure is sufficiently lowered. However, there are
no large prospective clinical trials of antihypertensive therapy in
patients with established hypertensive nephrosclerosis which have
carefully analyzed the effect of blood pressure lowering on the rate of
decline in glomerular filtration rate.
The purpose of this study was to measure the rate of decline
in GFR in 87 patients with hypertensive nephrosclerosis randomized to
two different levels of diastolic blood pressure: strict (N=42) < 80
mmHg versus conventional (N=35) 85-95 mmHg. All patients had
long-standing hypertension and a baseline GFR of <70 (range 10-70)
ml/min/1.73 m2, 53/77 were African-American and 29 were women. The
patients were followed for a mean of 40 months. The mean rate of
decline in GFR was not significantly different between groups despite a
significant difference in mean follow-up diastolic blood pressure of
about 6 mmHg. Remarkably the mean rate of decline in GFR for both
groups was < 1.0 ml/min/year and neither rate was significantly
different from zero. Analysis of the estimated decline in GFR suggested
a trend to a slower decline in GFR in the "strict" group; however, this
was not significant. Nine patients developed ESRD during follow up and
7 of these were African-Americans.
This is an exciting finding which has important implications
for management of hypertensive nephrosclerosis as well as for the design
of future clinical trials in hypertensive progressive renal diseases.
Still, the study has several limitations including small sample size
(limited power), limited follow-up, lack of demonstration of progression
prior to randomization and small difference in mean follow-up diastolic
blood pressure. Nevertheless, the data suggest that long-term control
of diastolic blood pressure within the range of 81-87 mmHg can slow or
arrest deterioration in renal function in patients with hypertensive
nephrosclerosis. Since the majority of patients in this study were
African-American, patients at highest risk for ESRD due to hypertension
should benefit greatly from early, aggressive blood pressure control.
(Toto)
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CRF by problem area :
Progression
H: Pathophysiology :
Kidney in hypertension