Estimates of blood pressure variability in adolescents using an automatic blood pressure measuring device

Knowledge of BP variability is important for BP screening and for the design of studies with BP as an outcome. We calculated estimates of the between-visit and within-visit variances from data obtained using an automated BP.device (Dinamap) in 776 students, aged 13-17 years, in the Exeter-Andover Project. Each subject had his or her BP measured three times per visit at up to 24 weekly visits. We compared these estimates of variance with those published for adolescents using a standard mercury sphygmomanometer. For subjects measured using the Dinamap, the between-visit variance was greater for SBP and the within-visit variance for both pressures was almost three times greater than for subjects measured with the standard instrument.