Effect of control of hypertension on progressive renal failure.

This study assesses the direct effect of different degrees of blood pressure control on the progression of chronic renal failure (CRF) in 18 patients with nephropathies of varying etiology (Glomerular filtration rate [GFR]: 14.99 +/- 5.94 ml/min/1.73 m2). The study involves three consecutive phases; Phase 1 consisted of a retrospective analysis of blood pressure and biochemical data: mean diastolic blood pressure (MDBP) was 89.9 +/- 7.9 mmHg and the mean rate of decline in renal function was -68.9 1/mol of creatinine/month. Phase 2 consisted of a 6 months prospective period of frequent (monthly) follow-up and optimization of blood pressure control when MDBP was reduced to 83.9 +/- 6.5 mmHg (p < 0.001 cf phase 1) and the rate of decline in renal function fell to -25.2 1/mol/month (p < 0.05 cf phase 1). Phase 3 consisted of another 6-month period when further reduction of MDBP 77.1 +/- 6.6 mmHg (p < 0.01 cf phase 2) was brought about by the addition of the calcium antagonist nifedipine (10 mg thrice/daily). This was not associated with further improvement in the rate of decline of renal function as in this phase the rate of decline was -53.2 1/mol/month. This study confirms that frequent follow-ups with improved blood pressure control slow the rate of decline in renal function. Further reduction of diastolic blood pressure to below 80-85 mmHg could not be shown to confer additional benefit.