title: [The white coat effect during the first hour of ambulatory blood pressure].
abstract: OBJECTIVE
  To investigate the white coat effect during the first hour of ambulatory blood pressure and its effect on the ABPM.
  
  
  METHODS
  A total of 626 outpatients and inpatients (257 were male, 369 were female), whose ages ranged from 13 to 90 (average age: 55 years) were entered into this study. All subjects were taken measurements of clinic blood pressure. Ambulatory BP monitoring was applied to the nondominant arm between 8:30 to 9:29, and set the average BP value of this interval as the first hour blood pressure.
  
  
  RESULTS
  There was an obvious elevation of the first hour measurement than that of the other intervals of 24ABPM. The white coat effect (WCE) was greater in women than in men (average BP of 1(st) hour-average BP in daytime: (9.5 +/- 13.4)/(6.0 +/- 7.8) mm Hg (1 mm Hg = 0.133 kPa) vs. (5.5 +/- 11.9)/(4.2 +/- 7.8) mm Hg, P < 0.01), and there was no statistic significant difference was founded among different age groups.
  
  
  CONCLUSIONS
  The first hour of ambulatory blood pressure monitoring is associated with significantly elevated blood pressure. We propose that improved ambulatory blood pressure monitoring recordings would be obtained in clinical practice, and more particularly in research applications, if 25 hours ambulatory blood pressure monitoring was carried out, excluding the first hour from the summary analyses.
authors.affiliation: Hypertension Center and Department of Evidence Based Medicine, Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Jian-feng
authors.initials: JF
authors.lastname: Huang
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.forename: Jian-xin
authors.initials: JX
authors.lastname: Li
authors.forename: Li-xia
authors.initials: LX
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000523:psychology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000209:etiology / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult