White coat hypertension and white coat effect similarities and differences*

The rise in blood pressure (BP) associated with clinical visit (white coat effect) may be one basic mechanism of white coat hypertension (persistently raised clinic BP together with a normal BP outside the clinic), but the relations between white coat hypertension, white coat effect, and target organ damage have not yet been assessed on large populations. Thus, we performed 24-h noninvasive ambulatory BP monitoring and 2D-guided M-mode echocardiography in 1,333 untreated subjects with essential hypertension and 178 control normotensive subjects. White coat hypertension was defined by an average daytime ambulatory BP < 131/86 mm Hg in women and < 136/87 mm Hg in men and its prevalence was 18.9% (n = 252). The white coat effect was calculated for systolic and diastolic BP as the difference between clinic BP and average daytime ambulatory BP. Echocardiographic left ventricular mass was slightly but not significantly greater in the group with white coat hypertension than in the normotensive group (93 v 87 g/m2, P = NS), and increased in the group with ambulatory hypertension (112 g/m2, P < .01). The prevalence of white coat hypertension markedly decreased from the first to the fourth Joint National Committee V (JNC V) stage of severity of hypertension (186/559 subjects (33%) in I; 59/501 (11%) in II; 7/230 (3%) in III; 0/43 (0%) in IV; P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)