title: No further decrease in blood pressure when the interval between readings exceeds one hour.
abstract: OBJECTIVE
  The assessment of blood pressure (BP) in individuals is traditionally based on a few BP readings obtained at intervals of just a few minutes. We examined if increasing intervals between BP readings on one visit would have an impact on the BP estimates.
  
  
  METHODS
  We conducted an examination survey of cardiovascular risk factors in the general population aged 25-64 years in Seychelles (Indian Ocean), attended by 1255 of 1565 eligible participants. BP was measured once shortly after participants' arrival to the study centers (BP1) and twice before discharge, 15-351 min later (BP2, BP3; separated by 2 min).
  
  
  RESULTS
  Mean (standard error) BP1 was 135.1 (0.7)/87.9 (0.4) mmHg, BP2: 130.7 (0.6)/85.1 (0.4) mmHg and BP3: 128.4 (0.6)/83.9 (0.3) mmHg. The difference in BP between the first and the last measurements (DeltaBP1-BP3) was, respectively, 5.8 (1.3)/2.6 (0.9) mmHg for a time interval between BP1 and BP3 of 15-60 min, 6.3 (0.5)/3.9 (0.3) mmHg for 61-120 min, 6.9 (0.6)/4.1 (0.4) mmHg for 121-240 min and 7.4 (0.7)/4.3 (0.5) mmHg for 241-351 min (P-trend for systolic/diastolic BP: 0.15/0.49). In multivariate analysis, both systolic and diastolic DeltaBP were associated with the initial BP level and the female sex but not with time (in minutes) between BP readings (for systolic/diastolic BP, P=0.12/0.34).
  
  
  CONCLUSIONS
  The decrease in subsequent BP readings obtained did not differ whether the time interval between BP measurements was larger or smaller than 1 h. This indirectly suggests that extending the time interval between repeated BP readings on one single visit is unlikely to be a valid, alternative strategy to the recommendation of gathering BP readings on several, separate visits to define hypertension.
authors.affiliation: Community Prevention Unit, Institute of Social and Preventive Medicine, University Hospital Center, University of Lausanne, Switzerland.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chiolero
authors.forename: Jacqueline C
authors.initials: JC
authors.lastname: Witteman
authors.forename: Bharathi
authors.initials: B
authors.lastname: Viswanathan
authors.forename: Julita
authors.initials: J
authors.lastname: William
authors.forename: Pascal
authors.initials: P
authors.lastname: Bovet
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors