WHITE COAT EFFECT IN 35 CONSECUTIVE HYPER TENSIVE PATIENTS - METHOD OF QUANTIFICATION - ROLE OF DOCTOR-PATIENT DIALOG

The << white coat >> effect, an alarm reaction to the presence of a do ctor, is an important cause of blood pressure variability, the frequen cy, amplitude and mechanisms of which are only partially understood. I n order to evaluate these factors, a prospective study was undertaken in 35 consecutive patients referred for assessment of clinical hyperte nsion. The alarm reaction was investigated during the consultation, at the time of interrogation, in periods of silence, in the sitting and upright positions. Twenty-four to forty-eight measurements (average 36 .8) of the blood pressure and heart rate were performed in each patien t with a Diasys 200 R monitor. The ambulatory period of 3 to 5 hours a fter the consultation provided 12 to 24 measurements (average 20.7) wh ich were considered to be the reference for comparison with the consul tation period. A total of 2038 measurement were made and analysed. Ana lysis of variance (GLM) for each patient and for the whole group gave an assessment of the alarm reaction during the patient-doctor dialogue and periods of silence with reference to the ambulatory period. Durin g the ambulatory period, the average and standard deviation for systol ic pressure were 134 +/- 0.7 mmHg, and for diastolic pressure 93.1 +/- 0.6 mmHg. These pressures were significantly lower than during the tw o periods of consultation, with and without dialogue (p < 0.0001). Dur ing the consultation, the systolic and diastolic blood pressure values were significantly higher during the dialogue than during the periods of silence (p < 0.0001). During the dialogue, the systolic pressure a ttained 153.7 +/- 0.7 mmHg and the diastolic pressure : 107.2 +/- 0.6 mmHg. During the periods of silence, the systolic pressure was 139.9 /- 0.8 mmHg and the diastolic pressure: 99.2 +/- 0.6 mmHg. Between the se periods of dialogue and silence there was a difference in average s ystolic pressure of 13.8 mmHg and diastolic pressure, of 8 mmHg. This study shows that the white coat effect can be quantified. It is charac terised by a significant increase in systolic and diastolic pressures during the consultation compared with the ambulatory period. In additi on, this effect is significantly increased during the dialogue with th e doctor compared with the periods of silence.