Terminology: Two terms are in current use to describe patients whose blood pressures are high only in a medical setting (white-coat hypertension and isolated office or clinic hypertension). The term white-coat effect is also commonly used to describe the pressor response to the clinic setting.
Definitions: White-coat hypertension is generally defined as a persistently elevated clinic blood pressure in combination with a normal ambulatory blood pressure (ABP). There is disagreement regarding the optimal cutoff point for ABP. The white-coat effect is operationally defined as the difference between the clinic blood pressure and daytime ABP. PREVALENCE OF WHITE-COAT HYPERTENSION: This varies according to the definition of white-coat hypertension and the population studied, but is approximately 20% among mild hypertensives, and increases with age.
Metabolic and biochemical aspects: Authors of some studies have suggested that white-coat hypertension is associated with metabolic abnormalities such as hyperlipidemia that lead to an increase in cardiovascular risk, but most have not found this. TARGET-ORGAN DAMAGE: Several measures of target-organ damage have been compared among normotensives, white-coat hypertensives, and sustained hypertensives; these include left ventricular mass, microalbuminuria, and carotid atherosclerosis. In general, target-organ damage in white-coat hypertension is less than that in sustained hypertension, but in some studies it has been found to be more prevalent than in normotensives.
Morbidity and mortality: Authors of a relatively small number of prospective studies have concluded that white-coat hypertensives have a lower risk of morbidity than do sustained hypertensives, but a larger number have drawn the more general conclusion that, when there is a discrepancy between the clinic blood pressure and ABP, the prognosis is more closely related to the ABP.
Management: When white-coat hypertensives are prescribed antihypertensive medication there is usually a decrease in clinic blood pressure, but little or no change in ABP. Thus drug treatment is not necessarily indicated. Another issue is the follow-up of white-coat hypertensives; there is general agreement that blood pressure outside the office should be monitored indefinitely. Some patient may have been wrongly classified as white-coat hypertensives, and others may progress to develop sustained hypertension.