Long-term renal function in primary hypertension. An epidemiological and pathophysiological study

Abstract

The purpose of this study was to investigate the influence of birth factors on adult blood pressure and to study the long-term renal function and hemodynamic changes in primary hypertension. The investigations were performed in two population-based samples of men derived from two large screening investigations on blood pressure, a screening investigation of 49-year old men and the Primary Prevention Study. Birth variables were studied in 430 subjects, born in 1926-27, who had participated in the screening investigation of 49-year-old men in Göteborg. The 14-year follow-up study of renal function and hemodynamics and urinary albumin excretion was performed in a stratified random sample of normotensive (n=11) and hypertensive (n=23) 49-year-old men. The effects of intensified blood pressure control (to a diastolic blood pressure, DBP <85 mm Hg) on renal function, hemodynamics and urinary albumin excretion, achieved by addition of felodipine or ramipril to ongoing treatment with ß-blockade, were investigated in 28 hypertensives. To determine if treated primary hypertension can lead to end-stage renal disease, the development of serum creatinine levels during 20 years in 686 hypertensive men from the Primary Prevention Study, recruited from a random third of the male population aged 47-55 years at entry, was studied. The findings demonstrate that preterm birth (gestational age less than 38 weeks) seemed to increase the risk of hypertension in adult life. They also showed, that good long-term blood pressure control (DBP <90 mm Hg) in primary hypertension can protect the kidneys from abnormal progressive decline in glomerular filtration rate and arrest proteinuria but does not normalise the reduced renal blood flow or the increased renal vascular resistance seen in primary hypertension. On decreasing the DBP to <85 mm Hg, achieved by addition of felodipine to ongoing treatment with ß-blockade, renal blood flow increased and renal vascular resistance decreased to levels no longer significantly different from normal. Addition of ramipril to ß-blockade reduced blood pressure less and renal function and hemodynamics did not normalise, but the urinary albumin excretion was lowered. The median value for the urinary albumin excretion remained within the range of the urinary albumin excretion of the normotensives in both the felodipine and the ramipril-treated groups. In the Primary Prevention Study, none of the hypertensives developed a hypertensive end-stage renal disease and only a few patients showed a slight increase in serum creatinine level before the age of 70. Thus, white patients with non-malignant primary hypertension without underlying renal disease and with good blood pressure control do not appear to develop progressive decline in kidney function or hypertensive end-stage renal disease.