title: Marked underestimation of blood pressure control with conventional vs. ambulatory measurements in an urban, developing community of African ancestry.
abstract: BACKGROUND
  As groups of African descent may have higher nocturnal blood pressure (BP) for a given day BP than other ethnic groups, we ascertained whether this translates into differences in conventional (CBP) and 24-h ambulatory (ABP) BP control at a community level.
  
  
  METHODS
  Ambulatory 24-h, day and night BP (model 90207; SpaceLabs, Issaquah, WA) and CBP (mean of five values) control rates were determined in 689 randomly selected participants (>16 years) of African ancestry in South Africa. Target organ effects were determined from urinary microalbumin-to-creatinine ratios (ACR) and aortic pulse wave velocity (PWV, applanation tonometry).
  
  
  RESULTS
  Of the participants 45.7% were hypertensive and 22.6% were receiving antihypertensive medication. More participants had uncontrolled BP at night (34.0%) than during the day (22.6%, P < 0.0001). Uncontrolled CBP was noted in 37.2% of participants, while a much lower proportion had uncontrolled ABP (24.1%) (P < 0.0001). Marked differences in the proportion of hypertensive participants with uncontrolled CBP and ABP were noted (treated: CBP = 62.2%, ABP = 33.3%, P < 0.0001; all: CBP = 81.3%, ABP = 44.4%, P < 0.0001). These differences were accounted for by a high prevalence of isolated increases in CBP (white-coat effects) (treated = 35.9%; all = 39.4%). Indeed, after censoring data from participants with white-coat effects, similar CBP and ABP control rates were noted. Participants with white-coat effects had similar ACR and PWV values as participants with normal ABP and CBP.
  
  
  CONCLUSIONS
  In communities of African descent, despite worse BP control at night than during the day, a high prevalence of white-coat effects translates into a striking underestimation of BP control in hypertensives when employing CBP rather than ABP measurements.
authors: The Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors: Muzi J
authors: MJ
authors: Maseko
authors: Angela J
authors: AJ
authors: Woodiwiss
authors: Olebogeng H I
authors: OH
authors: Majane
authors: Nomonde
authors: N
authors: Molebatsi
authors: Gavin R
authors: GR
authors: Norton
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D044383:Black People / Q000208:ethnology*; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology; D003906:Developing Countries; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000208:ethnology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009819:Office Visits; D013019:South Africa; D016896:Treatment Outcome; D014505:Urban Population
chemical_list: D000959:Antihypertensive Agents