Janus faces of the white coat effect: blood pressure not only rises, it may also fall.

For reliable control of hypertension, it is essential to know the prevalence of the white coat effect (WCE), which is defined as either a difference of 10 mmHg or more in systolic blood pressure (BP) and/or a difference of 5 mmHg or more in diastolic BP measured by a general practitioner (GP), a nurse, or the patient him/herself. The objective was to assess the WCE in hypertensive patients visiting GPs in primary healthcare centres. A blinded, randomised study in six primary healthcare centres was conducted, where eight GPs, nine nurses and 210 patients (92 men and 118 women) on a hypertension control regimen participated. Heart rate and BP in GPs', nurses' and self-service rooms were measured twice using a sphygmomanometer and an automatic device. Altogether, 148 patients (70%) performed the self-measurements of BP and heart rate perfectly successfully in all the three rooms. These were included in the final analyses. One out of three patients (33%) showed a marked alerting WCE in the GP's room (systolic BP rose by at least 10 mmHg and/or diastolic BP by at least 5 mmHg). On the contrary, one out of 10 (10%) showed a marked relaxing WCE in the GP's room (systolic BP decreased by at least 10 mmHg and/or diastolic BP by at least 5 mmHg). It can be concluded that the WCE in general practice has two faces: an alerting reaction and a relaxing reaction. This should be taken into account in hypertension control.

RCT Entities:   Population Interventions Outcomes