Purpose: This study was undertaken to investigate whether there is a relationship between the white-coat effect and the cardiovascular complications of hypertension.

Patients and Methods: In 1,013 consecutive borderline to severe hypertensive outpatients (889 men) with a mean age (±SE) of 33.6 ± 0.5 years and a mean office blood pressure of 152.3 ± 0.6/95.5 ± 0.4 mm Hg, blood pressure was measured by noninvasive 24-hour ambulatory monitoring. Target organ damage was assessed by electrocardiogram, chest X-ray, echocardiography, and ophthalmoscopy. The degree of target organ damage and of left ventricular hypertrophy was assessed in the subjects divided according to the levels of their daytime blood pressure and the extent of their white-coat effect.

Results: The subjects with a high white-coat effect showed a greater degree of hypertensive complications than those with intermediate or a low white-coat effect. The significant association between the white-coat phenomenon and the hypertensive complications was confirmed by the results of stepwise regression analyses, where sex, age, duration of hypertension, and ambulatory blood pressure were added to the model. A two-way ANOVA showed that both ambulatory blood pressure and the white-coat effect were related to the degree of target organ damage and to left ventricular hypertrophy. Moreover, daytime blood pressure and the white-coat effect showed an interactive effect on hypertensive complications, as the influence of the white-coat effect on end organs increased with increasing levels of ambulatory blood pressure.

Conclusions: The present results show that the white-coat effect is related to the degree of hypertensive complications and that this association is stronger in the subject with more severe hypertension.