Comparison of blood pressure values-self-measured at home, measured at an unattended office, and measured at a conventional attended office.

Self-measured blood pressure (BP) at home (HBP) has been commonly used in clinical practice. Although the unattended office BP (UBP), in which a patient is left alone before and during the measurement, has been investigated, the advantages of UBP over HBP or conventionally measured attended office BP obtained using automated devices (CBP) remain unclear. We performed a multicenter clinical study in Japan to compare the UBP, CBP, and HBP among 308 patients with hypertension at 3 clinics (women, 57.8%; mean age 71.8 years; under antihypertensive drug therapy, 96.4%). The patients measured HBP twice in the morning and twice in the evening for 5 days according to the Japanese Society of Hypertension guidelines. Using the Omron HEM-907 cuff-oscillometric device, the UBP and CBP were measured in line with the protocol in the Systolic blood PRessure INtervention Trial (SPRINT) and in accordance with the guidelines, respectively. Correlation coefficients were ≤0.16 for the comparison of UBP versus morning and evening HBP for the systolic measurement, whereas they were approximately 0.5 (P < 0.001) for the diastolic measurement. The difference between UBP minus HBP was small on average but varied among individuals (mean ± SD for UBP minus morning HBP: 0.9 ± 17.8/-4.5 ± 10.5 mmHg; UBP minus evening HBP: 5.7 ± 17.8/-0.1 ± 11.3 mmHg). In contrast, the measurement values of CBP and UBP were highly correlated (r ≥ 0.72), but the difference between CBP minus UBP was 10.4 ± 12.0/4.2 ± 6.5 mmHg. Based on the low correlations and wide range of differences, UBP cannot be used as an alternative to HBP.