Predictors of future established hypertension and diurnal blood pressure variability in borderline hypertension.

Among 157 patients with borderline hypertension 33.8% developed established hypertension (H), 28.6% became normotensive (N), and 37.6% still had borderline hypertension (BH) during a 3 to 10 year follow-up period (an average of 6.4 years). Significant differences in the clinical data among these 3 groups at the first examination were observed in systolic blood pressure (SBP), diastolic blood pressure (DBP), age, obesity, known duration of hypertension and SV1 + RV5 on an electrocardiogram. Analysis of variance showed that SBP increased with age in both sexes, while DBP of men less than 49 years of age was higher in the H group than in the other groups. Obesity and duration of hypertension appeared to contribute to the later development of hypertension because of a higher blood pressure. Obese men in the H group generally had higher DBP than nonobese patients in the other groups. Men with a longer history of hypertension in the H group also had a higher initial blood pressure. SV1 + RV5 in many of the subgroups of the H group was often higher in similar subgroups of the other groups. These inter-subgroup differences may affect the statistical differences in the above-mentioned parameters among the 3 groups. The mean value and standard deviation of SBP and DBP of diurnal blood pressure measurements were in the order of established hypertensives, borderline hypertensives and normotensive subjects when power-normal distribution was applied. There was no evidence that lability of blood pressure was a characteristic feature of borderline hypertension.