Clinical characteristics of isolated clinic hypertension.

Objective: To analyze the clinical characteristics of patients with isolated clinic hypertension (ICH) compared with other hypertensive patients, and to evaluate the capacity of physicians to predict a diagnosis of ICH.

Methods: A cross-sectional, comparative multicenter descriptive study was made of 6176 hypertensive individuals without pharmacological treatment, subjected to ambulatory blood pressure monitoring (ABPM). In 2611 cases, ABPM was prescribed due to suspected ICH. The participants were consecutively selected in primary care centers and hospital hypertension units in all Spanish Autonomous Communities. ICH was defined by clinical blood pressure (BP) >or= 140 mmHg (systolic) or >or= 90 mmHg (diastolic), with diurnal ambulatory BP < 135 and < 85 mmHg (ICH1) or BP < 130 and < 80 mmHg (ICH2) or 24-h BP < 125 and < 80 mmHg (ICH3).

Results: ICH1, ICH2 and ICH3 criteria were met by 1807 (29.2%), 960 (15.5%) or 1133 (18.3%) subjects, respectively. Total sample mean age (SD) was 51.8 (14.1) years, and clinical BP 145.7 +/- 17.3/89.3 +/- 11.3 mmHg. Compared with the rest of the hypertensive individuals, the patients with ICH were predominantly female, of older age, with fewer smokers, and increased frequency of obesity. Moreover, they were more frequently nondippers, and with greater systolic BP in the office (P < 0.05), except when we used ICH3 criteria. The sensitivity and specificity of the physician predictions in relation to suspected ICH1, ICH2 and ICH3 were 48.7 and 60.4%, 52.9 and 59.7%, and 52.3 and 60.0%, respectively.

Conclusions: The prevalence of ICH is between 15 and 29%, depending on the defining criterion used. The 24-h ICH criteria are not affected by awake/sleep biases, and should be preferred. Clinical capacity for predicting ICH is low.