Reproducibility of Office and Out-of-Office Blood Pressure Measurements in Children Implications for Clinical Practice and Research

This study aimed to evaluate the reproducibility of office (OBP), ambulatory (ABP), and home blood pressure (HBP) measurements in children and adolescents, and their implications in diagnosing hypertension in clinical practice and in pediatric hypertension research. Apparently healthy children and adolescents referred for suspected hypertension were included. Measurements of 2-visit OBP, 7-day HBP, and 24-hour ABP were performed twice, 1 to 6 months apart. Reproducibility was quantified using the SD of differences between repeated measurements. The sample size of clinical trials comparing the efficacy of antihypertensive drugs using each method was calculated. Fifty-eight individuals were analyzed (mean age, 13.0 +/- 2.9 years, 60.3% boys). The reproducibility of 24-hour ABP (SD of differences 5.7/4.5 systolic/diastolic) and HBP (5.9/5.0 mm Hg) were comparable and superior to that of visit-2 OBP (9.2/7.8) and awake (6.7/5.5) or asleep ABP (7.6/6.1). As a consequence, a parallel-group comparative trial aiming to detect a difference in the effect of 2 drugs of 10 mm Hg systolic BP, would require 36 participants when using OBP measurements, 14 using 24-hour ABP, and 15 using HBP (102/34/42 respectively for detecting a 5 mm Hg difference in diastolic BP). For a crossover design trial, the corresponding sample sizes are 9/3/4 for systolic BP and 26/9/11 for diastolic, respectively. These data suggest that in children and adolescents 24-hour ABP and 7-day HBP have similar reproducibility, superior to OBP and daytime or asleep ABP. These findings have major implications in diagnosing hypertension in children in clinical practice and in designing clinical research trials in pediatric hypertension.