An Independent Predictor of Prognosis in Essential Hypertension

To determine the prognostic significance of ambulatory blood pressure, we prospectively followed for up to 7.5 years (mean, 3.2) 1187 subjects with essential hypertension and 205 healthy normotensive control subjects who had baseline off-therapy 24-hour noninvasive ambulatory blood pressure monitoring. Prevalence of white coat hypertension, defined by an average daytime ambulatory blood pressure lower than 131/86 mm Hg in women and 136/87 mm Hg in men in clinically hypertensive subjects, was 19.2%. Cardiovascular morbidity, expressed as the number of combined fatal and nonfatal cardiovascular events per 100 patient-years, was 0.47 in the normotensive group, 0.49 in the white coat hypertension group, 1.79 in dippers with ambulatory hypertension, and 4.99 in nondippers with ambulatory hypertension. After adjustment for traditional risk markers for cardiovascular disease, morbidity did not differ between the normotensive and white coat hypertension groups (P=.83). Compared with the white coat hypertension group, cardiovascular morbidity increased in ambulatory hypertension in dippers (relative risk, 3.70; 95% confidence interval, 1.13 to 12.5), with a further increase of Target-organ damage in essential hypertension is more closely associated with ambulatory than with clinic blood pressure (BP),and for any given value of clinic BP it is directly related to the mean levels and variabilityof ambulatory BP. Since targetorgan damage is a powerful predictor of morbidity and mortality in hypertension,-' ambulatory BP might offer prognostic information beyond that provided by clinic BP. Only one large prospective study, based on daytime ambulatory BP readings, has been published concerning the prognostic significance of ambulatory BP in essential Received May 24, 1994; accepted in revised form August 5, 1994. From Ospedale Generale Regionale "R. Silvestrini," Unita Organica di Malattie Cardiovascolari e Medicina Interna (P.V., C.P., C.B., A.C., M.B., C.G., I.Z.); Ospedale "Beato G. Villa," Citta delta Pieve (G.S.); Ospedale "S. Agostino," Castiglione del Lago (M.G.); Cattedra di Statistica e Biometria, Istituto di Medicina Interna e Medicina Vascolare delPUniversita di Perugia (A.S., C.S.); and Istituto di Medicina Interna e Scienze Endocrine e Metaboliche dell'Universita di Perugia (G.R.) (Italy). Presented in part at the 15th Scientific Meeting of the International Society of Hypertension, Melbourne, Australia, March 1994, and at the Ninth Annual Scientific Meeting of the American Society of Hypertension, New York, NY, May 1994. Reprint requests to Dr Paolo Verdecchia, Ospedale Generale Regionale "R. Silvestrini," Unita Organica di Malattie Cardiovascolari e Medicina Interna, Localita San Sisto, 06100 Perugia PG, Italy. © 1994 American Heart Association, Inc. morbidity in nondippers (relative risk, 6.26; 95% confidence interval, 1.92 to 20.32). After adjustment for age, sex, diabetes, and echocardiographic left ventricular hypertrophy (relative risk versus subjects with normal left ventricular mass, 1.82; 95% confidence interval, 1.02 to 3.22), cardiovascular morbidity in ambulatory hypertension was higher (P=.0002) in nondippers than in dippers in women (relative risk, 6.79; 95% confidence interval, 2.45 to 18.82) but not in men (P=.9\). Our findings suggest that ambulatory blood pressure stratifies cardiovascular risk in essential hypertension independent of clinic blood pressure and other traditional risk markers including echocardiographic left ventricular hypertrophy. Cardiovascular morbidity is low in white coat hypertension and exceedingly high in women with ambulatory hypertension and absent or blunted blood pressure reduction from day to night. (Hypertension. 1994;24:793-801.)