Reproducibility of ambulatory blood pressure in treated and untreated hypertensive patients

Objective: We tested the reproducibility of ambulatory blood pressure (ABP), BP variability, and BP reduction in hypertensive patients. Methods: Forty-two hypertensive patients were enrolled, and ABP monitoring (ABPM) was performed four times in each patient: twice before and twice after the treatment. Morning BP was defined as the average of 2 h after waking, and morning BP surge (MBPS) was defined by four ways: sleep-trough, preawake, morning-evening and morning-after-bed surge. The BP variability was evaluated by standard deviation, weighted standard deviation, coefficient of variation and average real variability. The reproducibility was compared using the repeatability coefficient and the Bland-Altman's method. Results: The awake, sleep, 24-h and morning BP were well corresponded in the first and the second ABPM values in each period. The four measures of BP variability also corresponded well between the first and the second ABPM values in each period. MBPS did not correspond well in each period when it was defined by diaries, but the extent of correlation was improved when it was defined by actigraphy. The reproducibility of BP-lowering effect was fair when it was defined by a single parameter, but not very good when it was defined by two parameters (e.g. MBPS). Conclusion: The reproducibility of ABP levels and BP variability was fairly good and that of MBPS was moderate when defined by actigraphy. The good reproducibility of BP reduction means that each single ABPM, before and after the treatment, is acceptable for the assessment of drug efficacy.