White Coat Effect and White Coat Hypertension: What Do They Mean?

Gianfranco Parati, MD, Grzegorz Bilo, MD, Giuseppe Mancia, MD


Cardiovasc Rev Rep. 2003;24(9) 

In This Article

Abstract and Introduction

The alerting reaction to the physician's visit is known to induce a blood pressure rise termed "white coat effect." This phenomenon has often been associated with a clinical condition characterized by a persistently high blood pressure in the doctor's office and a persistently normal blood pressure at other times, a condition commonly referred to as "isolated office hypertension" or "white coat hypertension." In this paper the direct and indirect methods of assessing these phenomena are briefly discussed, together with the sometimes discrepant definitions used when referring to them. The possible clinical relevance of both white coat effect and isolated office hypertension is addressed.

The occurrence of a transient increase in blood pressure (BP) at the time of sphygmomanometric measurement in the clinic environment was first described in 1897 by Riva-Rocci.[1] Nearly 50 years later, Ayman and Goldshine[2] observed that BP values measured by the patient at home were invariably lower than BP values recorded by physicians in their office, and that this difference persisted over an average observation period of 104 weeks. The quantitative assessment of this phenomenon was first provided in 1983 by Mancia et al.[3] through use of continuous intra-arterial ambulatory BP recording. It was observed that the BP rise during a physician's visit: 1) actually starts with the beginning of the visit even before the time of actual BP measurement; 2) persists for approximately 10-15 minutes (i.e., the duration of the visit); 3) is accompanied by a parallel rise in heart rate; 4) is quantitatively relevant, there is maximal increase in intra-arterial systolic and diastolic BP during the first 2-4 minutes[3,4] of the visit amounting on average to +27/+14 mm Hg; and 5) is characterized by a pronounced between-subject variability, making the prediction of individual pressor responses to the physician's visit impossible.[3] Figure 1 demonstrates a representative pattern of BP changes during a physician's visit, showing an original intra-arterial BP tracing taken from a 24-hour ambulatory BP recording performed by the Oxford technique through a catheter percutaneously inserted into the radial artery. During the ambulatory recording, a 15-minute visit by a physician unknown to the patient was scheduled. During consultation, the patient's BP increased, reaching a peak in the first 4-5 minutes, and subsequently declined toward pre-visit values. However, even at the last minute of the visit, BP values were still higher than during the periods preceding or following the physician's visit. Figure 2 shows the pronounced interindividual variability in the pressor effects of a physician's visit. A much lower and a more transient BP rise was recorded when a nurse, rather than a doctor, was in charge of the visit and of the related conventional BP measurement. The increase in BP and heart rate associated with the physician's visit did not show a tendency to easily vanish, but remained of comparable magnitude during four consecutive visits repeated over a 48-hour intra-arterial recording period (always performed by the same physician or nurse).[4]

Original intra-arterial blood pressure (BP) recording performed in a patient before, during, and after a 15-minute visit by a physician unknown to the patient. Arrows indicate the beginning and the end of a 15-minute doctor's visit. ABP=pulsatile arterial BP; MAP=mean BP; *ABP=BP values integrated every 10 minutes; HR=heart rate Reprinted with permission from Lancet. 1983;2:695-698.[3]

Maximal changes in intra-arterial systolic and diastolic blood pressure (BP) (SBP/DBP) recorded during the first 4-5 minutes of a physician's visit as compared with the baseline average SBP and DBP values of the 5 minutes preceding the visit (see Figure 1 for more details). Data are shown as individual changes (dots) from 48 hypertensive patients. The horizontal lines refer to the average values of these peak changes in SBP and DBP for the group as a whole. Reprinted with permission from Lancet. 1983;2:695-698.[3]

This phenomenon, which represents one of the major problems associated with conventional clinic BP measurement, has been interpreted as the hemodynamic result of patients' alarm reactions to a physician's visit, a reaction that was later referred to as the "white coat effect" (WCE).[5] Its clinical importance is related to the possibility that it might lead to overestimation of initial BP levels and/or to underestimation of the effect of antihypertensive treatment. These original observations were subsequently confirmed by several papers based on an indirect quantification of this phenomenon, focusing on the finding that clinic BP is in most cases higher than ambulatory BP. This was taken as a demonstration that the WCE does exist in real life and is not only a research artifact.[6]