Prevalence and clinical significance of a greater ambulatory versus office blood pressure ('reversed white coat' condition) in a general population

Background: Attention has recently been directed to a condition termed 'reversed white coat' because of an av. 24 h ambulatory blood pressure (BP) uncharacteristically greater than office BP. No data are available, however, on the prevalence of this condition in the general population, as well as on its relationship to BP, age, gender, antihypertensive treatment and cardiac organ damage. Methods: In 3200 individuals (participation rate 64%), randomly selected to be representative of the residents of Monza (Milan, Italy) for sex and decades of age (25 to 74 years), we measured office BP (av. of three measurements, sphygmomanometry), ambulatory BP (automatic readings every 20 min, Spacelabs 90207) and left ventricular mass (echocardiog.). Results: A 'reversed white coat' condition (identified when 24-h av. ambulatory systolic, diastolic or mean were higher than the corresponding office values) was seen in 15% (diastolic) to 26% (systolic) of the population as a whole. Prevalence was greater (34-40%) when the difference between office and daytime BP was considered but in both instances it remained less than the prevalence of the white-coat phenomenon. A reversed white-coat condition was similarly frequent in males and females and showed a steep redn. with age and increasing office BP values. Prevalence was greater in hypertensive subjects in whom treatment achieved BP control than in untreated or unsatisfactorily treated individuals. Within each quartile of 24-h or office BP, left ventricular mass index adjusted for demog. and biochem. values was similar in reversed white coat vs. the remaining subjects. The absence of any assocn. with left ventricular hypertrophy scores against the clin. significance of this phenomenon.