Nighttime Home Blood Pressure in Children: Association with Ambulatory Blood Pressure and Preclinical Organ Damage

Abstract

This study aimed to investigate a novel technique for nighttime blood pressure evaluation using a home blood pressure (HBP) monitor in children and adolescents, in terms of association with ambulatory blood pressure (ABP) and preclinical organ damage. Children and adolescents (aged 6-18 years) referred for elevated blood pressure were evaluated with ABP (24 hours) and HBP monitoring during daytime (7 days, duplicate morning and evening measurements) and nighttime (automated asleep measurements for 3 nights with 3 hourly measurements/night; Microlife WatchBP Home N). Preclinical organ damage was assessed by echocardiographic left ventricular mass index, carotid intima-media thickness, carotid distensibility coefficient, and carotid-femoral pulse wave velocity. Ninety-one individuals were analyzed (mean age 13.3±2.8 years; 54 men; 17 with elevated ABP). There was a close association between daytime (awake) ABP and HBP (r=0.81/0.77, systolic/diastolic) and between nighttime (asleep) values (r=0.78/0.60) (all P<0.05). Daytime HBP was slightly lower than daytime ABP (difference, -2.0±6.5/-0.9±5.1 mm Hg, systolic/diastolic, P<0.01/NS), whereas nighttime HBP was slightly higher than nighttime ABP (2.6±7.2/2.2±6.1 mm Hg, P<0.01 for both). Nighttime systolic ABP and HBP were correlated with left ventricular mass index (r=0.37 and 0.29, respectively), carotid intima-media thickness (0.45, 0.47), carotid distensibility coefficient (-0.22, -0.20), and carotid-femoral pulse wave velocity (0.47, 0.53) (P=NS for comparisons between methods). The agreement between nighttime HBP and ABP in identifying individuals with nighttime hypertension (≥95th percentile for nighttime ABP) was 82% (κ=0.49; P<0.01) and nondippers 57% (κ=0.19; P=0.03). In conclusion, in children and adolescents, nighttime HBP monitoring is feasible, is closely associated with nighttime ABP and similarly associated with preclinical organ damage.