title: The importance of the clinical observer in the development of a white-coat effect in African-American patients with hypertension.
abstract: BACKGROUND
  As the office-awake blood pressure (BP) difference (white-coat effect) in African-Americans has not been evaluated, we studied the ethnicity, professional status (nurse versus doctor) and sex of the observer on the white-coat effect in African-American patients with hypertension.
  
  
  METHODS
  Seated clinical BP measurements were obtained in random order by an African-American male research physician, a Caucasian male research physician, and a Caucasian female nurse who is of similar age and clinical experience. Within 1 week, ambulatory BP recordings were performed.
  
  
  RESULTS
  A total of 65 African-American patients [54+/-13 years, 55% women, body mass index (BMI) 31+/-6 kg/m, 62% on drug therapy, 28% current smokers] participated in the study. Twenty-two percent had a systolic white-coat effect >20 mmHg and 49% had a diastolic white-coat effect >10 mmHg (average of all observers). Although there were no differences in the magnitude of the white-coat effect among the three study observers, the primary physician's diastolic white-coat effect was significantly greater than that of the African-American physician (14+/-12 vs. 9+/-12, P=0.05), but not the systolic white-coat effect (16+/-16 vs. 10+/-16 mmHg, P=0.09). BMI positively correlated with the systolic and diastolic white-coat effect (r=0.30, P=0.02 and r=0.41, P=0.0001), but this correlation was true only for female patients in multiple regression analyses. BMI significantly predicted the systolic (P=0.043) and diastolic (P=0.004) white-coat effects.
  
  
  CONCLUSIONS
  A white-coat effect is relatively common in African-American patients with hypertension and is the largest when the observer is their usual doctor. The clinical observer's ethnicity or sex does not play an important role in generating a white-coat effect in African-American patients with hypertension.
authors.affiliation: Section of Hypertension and Clinical Pharmacology, Center for Cardiology and Cardiovascular Biology, University of Connecticut School of Medicine, Farmington, Connecticut 06030-3949, USA.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Labinson
authors.forename: Sharon
authors.initials: S
authors.lastname: Giacco
authors.forename: Henry
authors.initials: H
authors.lastname: Gift
authors.forename: George A
authors.initials: GA
authors.lastname: Mansoor
authors.forename: William B
authors.initials: WB
authors.lastname: White
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D001795:Blood Pressure Determination; D018660:Blood Pressure Monitoring, Ambulatory; D015992:Body Mass Index; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D010817:Physician-Patient Relations; D010820:Physicians; D012737:Sex Factors; D044465:White People