Conventional office blood pressure measurements and unattended automated office blood pressure compared with home self-measurement and 24-h ambulatory blood pressure monitoring

Objective To assess whether automated office blood pressure (BP) (AOBP) measurement is a better method for measuring BP in the office than conventional techniques and an alternative to out-of-office BP measurements: home-self BP (HSBP) or ambulatory BP monitoring (ABPM). Methods We conducted a cross-sectional study of 74 patients and compared AOBP with the conventional technique using a mercury sphygmomanometer and with both out-to-office BP measurements: HSBP of 7 days (three measurements in the morning, afternoon, and night) and daytime ABPM. In addition, we compared BP values obtained using HSBP and ABPM to determine their level of agreement. We used ANOVA to compare means, Bland-Altman, and intraclass correlation coefficients (ICC) for concordance. Results BP values obtained by the two office methods were similar: conventional 147.2/85.0 mmHg and AOBP 146.0/85.5 mmHg (P > 0.05) with good agreement (ICC 0.85). The mean SBP differences between AOBP and HSBP (P < 0.001) and between AOBP and ABPM (P < 0.001) were 8.6/13.0 mmHg with limits of agreement of -21.2 to 38.5 and -18.4 to 44.3 mmHg, respectively. The average SBP values obtained by HSBP were 4.3 mmHg higher than those obtained by ABPM (P < 0.01). Conclusion Our study showed good agreement and concordance between the two office methods as well between the two out-to-office methods, although there was a significant difference in the mean SBP between the HSBP and ABPM. Moreover, AOBP was not comparable to either HSBP or ABPM; therefore, the estimation of out-to-office BP using AOBP is not supported.