Factors associated with the development of stable hypertension in young borderline hypertensives.
To identify factors predisposing subjects to the development of stable hypertension and to estimate their relative importance in 70 young patients with borderline hypertension monitored for 10 years. Longitudinal evaluation of the incidence of stable hypertension [diastolic blood pressure (DBP) > 95 mmHg]. Patients were examined at baseline by determination of resting blood pressure, intracellular sodium level and individual pressor response to mental arithmetic and to intravenous saline loading. They were re-examined after 10 years to assess the prevalence of established hypertension and the importance of some prognostic variables identified prospectively (age, sex, intracellular sodium level, baseline blood pressure, pressor response to stress and acute salt-sensitivity). The prevalence of sustained hypertension (DBP > 95 mmHg) was 35.8% after 10 years of follow-up study. Subjects developing hypertension were older (26.9 +/- 1.3 versus 21.0 +/- 1.8 years) and showed a higher percentage of family history of hypertension (92 versus 64%) and of acute salt-sensitivity (72 versus 53%). The pressor response to mental arithmetic was greater in patients who developed hypertension (systolic blood pressure 26.9 +/- 1 versus 22.7 +/- 0.9 mmHg, P = 0.005 DBP = 16.6 +/- 0.8 versus 13.1 +/- 0.7 mmHg, P = 0.005), who also showed higher levels of intracellular sodium (30.7 +/- 0.6 versus 27.3 +/- 0.5 mmol/kg, P = 0.001). The same variables were found to be related to the development of hypertension in a multivariate analysis and the concomitant presence of 4-5 risk factors was associated with a reasonable predictive power for the identification of patients at high risk (sensitivity 72%, specificity 67%, predictive accuracy 76%). The present study demonstrates that borderline hypertensives at high risk of stable hypertension can be identified by the concomitant evaluation of some clinical and cellular characteristics directly related to long-term development of high blood pressure.