Variability between current definitions of 'normal' ambulatory blood pressure. Implications in the assessment of white coat hypertension.

Abstract
The assessment of white coat hypertension is complicated by the lack of generally agreed-on normal limits of ambulatory blood pressure. To assess the influence of four of these limits on the prevalence of white coat hypertension and the corresponding distribution of left ventricular hypertrophy, we performed 24-hour ambulatory blood pressure monitoring and echocardiographic studies in 346 untreated patients with essential hypertension and 47 age-matched normotensive control subjects. The upper limits of normal daytime ambulatory blood pressure were lower using standards drawn from clinically normotensive populations than using standards drawn, partly or entirely, from general populations. The prevalence of white coat hypertension differed markedly using the different standards, being 12.1%, 16.5%, 28.9%, and 53.2% (chi 2 = 346.0, p less than 0.0001). Left ventricular mass index averaged 77 g/m2 in the control group, 85 g/m2 in the two groups with white coat hypertension defined by using standards drawn fr...