K033: Albumin excretion rate in mild hypertension: A 5-year follow-up of the harvest study

The clinical significance of microalbuminuria in subjects with mild hypertension is not well known. We studied 947 young subjects (mean age = 33 ± 9 years) with stage I hypertension from the HARVEST Study. All patients underwent 24-hour ambulatory BP monitoring and 24-hour urine collection for albumin excretion rate (AER) assessment (by radioimmunoassay). Subjects were followed for 5 years and treated if they developed sustained hypertension (n = 132; clinic diastolic BP persistently ≥100 mmHg). In 384 patients ambulatory BP monitoring and AER assessment were repeated when they developed sustained hypertension (n = 86) or at the end of the follow-up (n = 298). Baseline AER was slightly greater in the subjects who developed the end-point than in those who did not (12 ± 23 vs 11 ± 35, p = 0.02). The prevalence of microalbuminuria (AER ≥ 30 mg/24 h) was 7.6% and 4.9%, respectively, in the two groups (p = ns). Among the subjects who repeated the tests, a nonsignificant increase in AER was observed in the 86 subjects who developed the end-point (from 11.6 ± 16.8 to 14.8 ± 33.4 mg/24 h), and a significant increase in the 298 subjects whose BP did not increase (from 11.1 ± 24.7 to 18.8 ± 63.2 mg/24 h, p < 0.000). In a multiple Cox regression analysis in which age and sex were included (n = 947) baseline AER was a marginal predictor for the development of sustained hypertension (p = 0.02). The predictive power of AER decreased when clinic BP was included in the model (p = 0.075) and completely disappeared when 24-hour BP was taken into account. The change in AER from baseline to second assessment (n = 384) was also unrelated to the development of the end-point. These results indicate that in a population of young subjects with borderline to mild hypertension AER is not helpful for identifying those subjects who develop more severe hypertension during the subsequent years.