The objective of the study was to investigate the reproducibility of office BP, home BP and 24-h ABPM over a period of one week. For this purpose, an office BP measurement was taken on study days 1 and 7 in 101 patients and an ambulatory 24-h ABPM was carried out on study days 7 and 14. In the time intervals between study days 1 and 7 and between study days 8 and 14, the patients measured their home BP themselves with an oscillometric wrist instrument.
One hundred and one participants were included in the study. All subjects were consecutively recruited from the outpatients of Medical Policlinic of the University of Bonn.
The data of 97 patients with complete data sets (55 men and 42 women, 69 participants with office-measured hypertension, 28 with office-measured normotension, 23 participants with antihypertensive treatment and 74 without treatment) were included in the statistical analysis. Hypertensive subjects measured home BP before taking antihypertensive medication. The antihypertensive treatment regime (frequency and timing) was not changed during the study period. 4 patients were excluded. The inclusion criteria were aged between 18 and 75 years and the presence of written consent to participate in the study. The exclusion criteria were significant arrhythmias, pregnancy and lactation. The University of Bonn issued a positive ethical vote on the study.
1. Office blood pressure measurement (office BP)
The blood pressure was measured in the doctor's office in accordance with the recommendations of the American Heart Association (AHA) and the European Society of Hypertension (ESH) after the participant had rested for five minutes in a sitting position [, ]. On study day 1, two measurements per upper arm were made with a two-minute interval between each measurements with the auscultatory blood pressure instrument from Acuson (Acuson Greenlight 300 with universal cuff). Office BP was measured with the same procedure only on the left upper arm on study day 7. The office BP was taken with a precision nearest 2 mmHg.
2. Blood pressure self-measurement (home BP)
The patients measured their blood pressure themselves with the oscillometric wrist instrument from Omron (wrist instrument HEM- 637 IT with position sensor). Between study days 1 and 7 and study days 8 and 14, the participants took two measurements on the left wrist each day in the morning between 6 and 9 a.m. and in the evening between 8 and 9 p.m. after sitting for five minutes with a two-minute interval between the two consecutive measurements. Hypertensive subjects measured home BP before taking antihypertensive medication. The antihypertensive treatment regime was not changed during the study period. Patients were instructed how to correctly use the oscillometric Omron wrist device for home BP measurement with a standardized 30 min. teaching program. The blood pressure parameters of the first week (day 1 to day 7) were compared with the results of the second week (day 8 to day 14). The HEM- 637 IT wrist device is validated according to the international protocol of the European Society of Hypertension . The home BP was measured in accordance with the user procedures and recommendations of the European Society of Hypertension .
3. Ambulatory 24-hour-blood pressure measurement (24-h ABPM)
The ambulatory 24-h blood pressure was performed according to AHA and ESH guidelines and measured with the ABPM 04 instrument of the company Meditech, Hungary, on the left upper arm on study day 7 and 14. In the period between 6 a.m. and 10 p.m., an oscillometric blood pressure measurement was taken automatically at intervals of 20 minutes, and at intervals of 45 minutes in the period between 10 p.m. and 6 a.m. The CardioTens is validated according to the BHS (British Hypertension Society) protocol