Long-term prognostic value of white coat hypertension: an insight from diagnostic use of both ambulatory and home blood pressure measurements.

The prognostic value of white coat hypertension (WCH) is still debated. In 2051 subjects representative of the general population of Monza, we measured office, ambulatory, and home blood pressure (BP). The risk of cardiovascular and all-cause mortality was assessed over 16 years in normotensive, sustained hypertensive, and WCH subjects, the last group being defined as usually done in clinical practice (ie, by normality of 1 out-of-office [ambulatory or home] BP with an office BP elevation). Compared with normotensive subjects, the risk of cardiovascular mortality, as adjusted for potential confounders, showed a progressive significant increase in WCH and sustained hypertensive subjects (2.04 and 2.94; P=0.006). In either group, a significant increase in adjusted risk was also seen for all-cause mortality. However, when the WCH group was subdivided into 2 subgroups, that is, subjects in whom both out-of-office BPs were normal (true WCH, 42%) or one BP was normal whereas the other was elevated (partial WCH, 58%), only the latter showed a significantly greater adjusted risk of cardiovascular and all-cause mortality (2.76 and 1.58; P<0.03). Compared with normotensive subjects, the partial WCH group also exhibited a marked increase in adjusted risk of developing sustained hypertension over a 10-year time period (2.58; P<0.0001), but in this case the risk was also increased in true WCH subjects (2.89; P<0.0001). Thus, WCH includes subjects with a widely different long-term risk of a cardiovascular event. To identify those at higher risk, measurements of both out-of-office BPs are desirable.