Reproducibility of ambulatory blood pressure measurements in essential hypertension

BACKGROUND: Data on the reproducibility of serial measurements of ambulatory blood pressure in hypertensive patients are lacking. The purpose of this study was to examine (1) the reproducibility of four consecutive ambulatory blood pressure measurements, and (2) the reproducibility of nocturnal falls in blood pressure in hypertensive patients. METHODS: Twenty patients with mild to moderate essential hypertension underwent four separate ambulatory blood pressure monitorings, on the same day of the week, at 30-day intervals. Antihypertensive therapy was discontinued for 2 weeks before each recording. Comparing the mean values of blood pressure over 24h, as well as diurnal, nocturnal and hourly periods, among the four recordings determined the reproducibility of blood pressure measurements. A day/night difference in mean systolic and in mean diastolic blood pressure defined the nocturnal fall in blood pressure. RESULTS: No significant differences were observed in either hourly, 24-h, diurnal or nocturnal systolic blood pressure, diastolic blood pressure and heart rate, or in the nocturnal fall in systolic and diastolic blood pressure among the four recordings. CONCLUSIONS: Hourly systolic blood pressure, diastolic blood pressure, heart rate, and nocturnal fall in blood pressure were reproducible in four ambulatory blood pressure monitorings recorded over 4 months. These findings suggest that ambulatory blood pressure monitoring is a reliable tool to monitor blood pressure changes.