[Does ambulatory determination of blood pressure allow the measurement of white coat effect?]

The aim was to find an objective indicator in order to evaluate white coat effect (WE). The first hour average values after placing an ambulatory blood pressure recorder (15 mn intervals) were compared to those of the 4 following hours of diurnal activity. A first hour systolic arterial blood pressure (SBP 1H) increase of 10 mmHg or more was considered as an ambulatory WE positive (AWE+) and was compared to clinical WE (CWE). CWE+ was observed in 78 pts and AWE+ in 72 among a group of 172 unselected pts referred for hypertension.

the correlation between AWE and CWE is weak (r = 0.49) but significant (p < 0.001). There was no difference between the two groups in age, sex, clinical blood pressure, heart rate or ambulatory BP after the first hour (table). There was a significant difference in SBP between the 2 groups (p < 0.001) during the first hour only. [table: see text]

Ambulatory blood pressure recording is able to recognize and evaluate the white coat effect. We suggest to consider independently the first hour of each recording and to compare it with the mean pressure measured during the period of diurnal activity.