Limited reproducibility of 24-h ambulatory blood pressure monitoring.

Results of 24-h ambulatory blood pressure monitoring (ABPM) including average blood pressure, variability, and nocturnal dipping are considered the gold standard for diagnosis and the best predictor of the future end organ damage in chronic hypertension. Here we report on the reproducibility of ABPM results for these three measures over a period of months. A total of 35 hypertensive patients (43% female, mean age 64 years), underwent two separate ABPM recordings within 14 weeks, with unchanged medical treatment and lifestyle in the interim. The day and night average blood pressure, dipping status of systolic pressure, and the standard deviation of systolic and diastolic blood pressure as a measure of variability were compared between the two recordings. Individual values for average systolic and diastolic pressures showed only a modest correlation between the two measurements (r = 0.56, r = 0.81, p < 0.01). Standard deviations of 24-h pressure were also positively but weakly correlated (r = 0.4, p < 0.001). The occurrence of dipping was reproducible in 71% of the patients. Average blood pressure, pressure variability, and dipping as assessed by ABPM are only moderately reproducible. Clinical decision-making based on single ABPM datasets should be made with caution, and repetition of ABPM seems justified in some cases.