Our objective was to test the agreement between nighttime home and nighttime ambulatory blood pressure (BP) and to compare their associations with left ventricular hypertrophy, arterial stiffness and carotid atherosclerosis.Design and method:
A population sample of 248 participants underwent measurements for 24-hour ambulatory BP and nighttime home BP (3 measurements at 2, 3 and 4 hours during 2 nights). We measured ambulatory BP with a Microlife WatchBP O3 device and home BP with a timer-equipped Microlife WatchBP Home N device. In addition, the participants underwent measurement of pulse wave velocity (PWV) and ultrasonographic examinations for left ventricular mass index (LVMI) and carotid intima-media thickness (IMT). The agreement between nighttime BPs were assessed with paired t-test, intra-class correlation and Bland-Altman plots. In addition, Pearson's correlation coefficients were calculated to assess the associations between nighttime BPs and end-organ damage, and the coefficients were compared with method described by Dunn and Clark.Results:
The mean number of ambulatory and home nighttime BP measurements was 16.6 ± 3.5 and 5.6 ± 1.3, respectively. No significant differences were found between mean ambulatory and home nighttime BPs (systolic/diastolic difference: 0.7 ± 7.6/0.2 ± 6.0 mmHg, p = 0.16/0.64). Furthermore, no systematic differences in systolic or diastolic nighttime BPs were identified between the two methods in Bland-Altman plots. Intra-class correlation coefficients for the relationships between systolic/diastolic nighttime BPs were high (0.81/0.71, p < 0.0001 for both). Correlation coefficients for BP indices and end-organ damage and their comparisons are shown in the Table. All home and ambulatory nighttime BP indices were positively correlated with PWV, LVMI, and IMT. The only significant difference in the correlations between end-organ damage and nighttime ambulatory or nighttime home BP, was a slightly stronger correlation between PWV and ambulatory systolic BP than for home systolic BP (p = 0.03, Table).Conclusions:
We conclude that home and ambulatory monitors produce similar nighttime BP values that had comparable associations with end-organ damage. Therefore, nighttime home BP measurement can be promoted as an alternative to ambulatory monitoring for measuring nighttime BP.