title: The impact of automated blood pressure devices on the efficiency of clinical trials.
abstract: By reducing measurement error, automated blood pressure (BP) devices should enhance the precision of BP estimation and thereby decrease sample size requirements in clinical trials of BP-lowering therapy. Enhanced precision would be particularly relevant to clinical trials assessing the efficacy of nonpharmacological therapies. In the present investigation, resting (clinic) BPs by the Dinamap 8100 (a stationary device) and the Accutracker II (an ambulatory device) were as precise as manual BPs given an equal number of observations by each method. However, both the Dinamap and Accutracker devices underestimated resting diastolic BP in comparison to the manual observers. Estimates of average daytime and 24-hour ambulatory BP, based on large numbers of observations over an extended period of time, were extremely precise. These findings suggest that the use of automated devices to measure resting BP may not reduce samples sizes, whereas use of ambulatory BP devices should reduce samples sizes considerably.
authors.affiliation: Johns Hopkins University School of Medicine, Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Hospital, Baltimore, Maryland 21205.
authors.forename: L J
authors.initials: LJ
authors.lastname: Appel
authors.forename: S
authors.initials: S
authors.lastname: Marwaha
authors.forename: P K
authors.initials: PK
authors.lastname: Whelton
authors.forename: M
authors.initials: M
authors.lastname: Patel
mesh_terms: D015982:Bias; D001794:Blood Pressure; D015924:Blood Pressure Monitors / Q000706:statistics & numerical data*; D002940:Circadian Rhythm; D006801:Humans; D006973:Hypertension / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D015203:Reproducibility of Results