O104 OPTIMAL NIGHTTIME BLOOD PRESSURE MONITORING SCHEDULE USING HOME MONITORS IN CHILDREN AND ADOLESCENTS: ASSOCIATION WITH AMBULATORY BLOOD PRESSURE AND PRECLINICAL TARGET-ORGAN DAMAGE

Background and Objective: To evaluate the optimal schedule for nighttime blood pressure (BP) assessed using home monitors (HBP) in terms of agreement with nighttime ambulatory BP (ABP) and association with indices of preclinical organ damage in children and adolescents. Methods: Apparently healthy children and adolescents (6-18 years) referred for elevated BP were subjected to (i) 24-hour ABP monitoring using a validated upper-arm cuff oscillometric device (Microlife WatchBP O3), (ii) HBP monitoring during daytime (7 days, duplicate morning and evening measurements) and nighttime (automated measurements, 3 nights, 3 hourly measurements/night) using a validated upper-arm cuff oscillometric device (total of 9 nighttime readings, Microlife WatchBP HOME N), (iii) carotid intima-media thickness (cIMT) measurement (ultrasonography), (iv) carotid-femoral pulse wave velocity (cfPWV) (Complior device; duplicate measurements), and (v) echocardiographic determination of left ventricular mass index (LVMI). Results: Forty-nine individuals were included (mean age 13.4±2.7 years, 51% males). There were no differences in nighttime HBP among individual readings or the average of different nights (night 1: 109.7±10.9/60.8±7.3 mmHg, systolic/diastolic BP; night 2: 109.1±11.7/59.7±8.6 mmHg; night 3: 109.1±11.5/60.4±8.4 mmHg, p=NS for all comparisons). By averaging an increasing number of nighttime systolic HBP readings, there was a consistent trend towards a stronger association of nighttime HBP with nighttime ABP (correlation coefficients r increased from 0.65 to 0.81), and with indices of preclinical organ damage (LVMI: 0.21 to 0.30; cIMT: 0.38 to 0.57; cfPWV: 0.60 to 0.69). There was no further improvement in these associations by averaging >4 nighttime readings. The diagnostic agreement between the two methods in detecting nocturnal hypertension was progressively improved by averaging more nighttime HBP readings with near plateau at 4 measurements. Conclusions: A two-night HBP monitoring schedule (6 readings) appears to be the minimum requirement for a reliable assessment of nighttime HBP in children and adolescents, which provides reasonable agreement with nighttime ABP and association with preclinical organ damage.