How often do office blood pressure measurements fail to identify true hypertension? An exploration of white-coat normotension

Background: The often-observed differences between ambulatory (ABP) and off ice blood pressure (OBP) measurements have brought attention to the problem of misdiagnoses. Although there has been much focus on white-coat hyperten sion (elevated OBP with normal ABP means), few studies have examined "white -coat normotension" (WCN; normal OBP with elevated ABP means). Objectives: To describe patients with WCN in terms of prevalence and quanti tative differences between ABP and OBP; to identify psychological and demog raphic features that discriminate them from true normotensive patients; and to offer possible corrections for diagnostic limitations of OBP measuremen ts in clinical practice. Design and Methods: Five OBP measurements and 10- to 12-hour daytime ABP mo nitoring in 319 presumed healthy participants. Results: Prevalence rates of WCN were 23% for systolic BP and 24% for diast olic BP. Participants with WCN were more often male, past smokers, and olde r and consumed more alcohol. Increasing the number of office readings and d iscarding the first office reading did nor improve the accuracy of OBP meas urements. Participants with BP of 10 mm Hg above or below the 140/90 office reading cutoff showed the lowest accuracy, with more than 50% of normotens ive diagnoses being incorrect. Conclusions: Office measures of BP lack sensitivity, missing a sizable port ion of individuals who have hypertensive mean ABP measurements. Subjects wi th WCN differ from true normotensive subjects on several demographic and li festyle variables. Only those office readings averaging 20 points above or below the 140/90 cutoff represent safe diagnostic information.