White-coat hypertension in adults and children

The measurement of blood pressure in the clinic triggers an altering reaction and a rise in blood pressure in the patient. Such a reaction is usually defined as a 'white-coat effect' or 'white-coat phenomenon', while the coexistence of persistently high office blood pressure with normal blood pressure outside the medical setting is referred to as 'white-coat' or 'office' hypertension. The white-coat effect can be estimated on a beat-to-beat basis using invasive (intra-arterial) or non-invasive methods, or, more commonly, by measuring the difference between office blood pressure and average daytime ambulatory blood pressure. The white-coat effect has little clinical importance because it is not associated with the target-organ damage and prognosis. We found that cardiovascular morbidities of healthy normotensive controls and subjects with white-coat hypertension did not differ. Results of a prospective study with intra-arterial blood pressure monitoring and preliminary prospective data from another group confirm our findings. A recent analysis of our database suggests that we should use a restrictive definition of white-coat hypertension (for example, average daytime blood pressure <130/80 mmHg) in order to identify the minority of subjects with low probabilities of developing a major cardiovascular event in the subsequent years. Also a recent document by the American Society of Hypertension suggests that one should use restrictive upper normal limits of ambulatory blood pressure (i.e., average daytime blood pressure <135 mmHg systolic and 85 mmHg diastolic). We have found that, over a follow-up period of 0.5-6.5 years, 37% of subjects with white-coat hypertension spontaneously evolve into ambulatory hypertension, with accompanying increase in left ventricular mass. The probability of developing ambulatory hypertension increased with the baseline values of ambulatory blood pressure, not of clinic blood pressure. A final answer on the clinical significance of white-coat hypertension will come from very large surveys of the natural history of this condition in the long term. Authors of these longitudinal studies should also compare the response to drug treatment of these subjects with that to life-style-modification measures.