Prevalence, predictive factor, and clinical significance of white-coat hypertension and masked hypertension in Korean hypertensive patients

Background : The prevalence and clinical significance of white-coat hypertension (WCHT) and masked hypertension (MHT) are unknown in Koreans. Here we measure the frequency of WCHT and MHT in hypertensive subjects and identify the epidemiologic and/or clinical factors that predict it in Korean subjects. Methods : This study is a retrospective analysis of a random sample from February 2004 to October 2005. All patients had measurements of blood pressure (BP) in the clinic and 24-hour ambulatory blood pressure monitoring (ABPM). Subjects were classified into four groups on the basis of daytime ambulatory BP and clinic BP level: 1) Normotension (NT), 2) MHT, 3) WCHT, and 4) sustained hypertension (SHT). Results : For all 967 patients, the mean clinic BP was 157.7±22.0/ 95.3±13.1 mmHg, and the mean daytime ambulatory BP was 136.4±15.0/ 86.2±10.7 mmHg. The NT, MHT, WCHT, and SHT groups consisted of 51 (5.3%), 55 (5.7%), 273 (28.2%), and 588 (60.8%) subjects, respectively. The left ventricular mass index was significantly higher in SHT than in the other groups, and was positively correlated with BP, especially ABPM. Compared with NT, the factors associated with MHT were younger age, male gender, higher BMI, clinic BP ≥130 mmHg, and alcohol consumption. Compared with SHT, the factors associated with WCHT were female gender, lower BMI, and clinic BP < 150 mmHg. Conclusions : WCHT and MHT were prevalent in the hypertensive population. ABPM was more predictive of target organ damage than clinic BP, and could be useful in identifying subjects at risk for WCHT and MHT.