Long-term reproducibility and usefulness of daytime recording of noninvasive 24-hour ambulatory blood pressure monitoring in borderline hypertension: A two-year follow-up study

We investigated the long-term reproducibility of noninvasive 24-hour ambulatory blood pressure monitoring (ABPM) compared with casual blood pressure measurements in 54 individuals (47+/-11 years) with borderline hypertension. ABPM and casual blood pressure measurements were obtained 3 times over 2 year period. ABPM data were analyzed to determine the average 24-hour blood pressure (24-BP), the average blood pressure during the waking hours (Day-BP), and the average blood pressure from the time the subject went to bed until he awoke (Night-BP). ABPM measurements were similar for Year 1, 2, and 3 (24-BP: Year 1; 1 30+/-10/79+/-6 mmHg; Year 2; 130+/-10/79+/-7mmHg; and Year 3; 130+/-10/78 +/-7mmHg). Bland-Altman analysis and standard deviation of the difference also indicated the reproducibility of 24-BP was better than casual pressure. The 24-BP was significantly correlated with both Day-BP and Night-BP for each year. Day-BP showed the stronger correlation. Our results suggest that Day-BP provides reproducible estimation in subjects with borderline hypertension.