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Background: Two electronic devices for self-measurement of blood pressure at the brachial artery - the Seinex SE-9400 (Seinex Electronics Ltd, Belfast, UK) and the Microlife BP 3AC1-1 (Microlife Corporation, Berneck, Switzerland) - were evaluated in two separate studies according to the International Protocol of the European Society of Hypertension.

Design: The international validation protocol is divided into two phases: the first phase is performed on 15 selected participants (45 blood pressure measurements); if the device passes this phase, 18 supplementary participants are included (54 blood pressure measurements) making a total number of 33 participants (99 blood pressure measurements) on whom the final validation is performed.

Methods: The same methodology recommended by the European Society of Hypertension protocol was applied for both studies. In each study and for each participant, four blood pressure measurements were taken simultaneously by two trained observers using mercury sphygmomanometers alternately with three measurements by the tested device. The difference between the blood pressure value given by the device and that obtained by the two observers (mean of the two observers) was calculated for each measure. The 99 differences were classified into three categories (<=5, <=10, <=15 mmHg). The number of differences in each category was compared with the number required by the ESH protocol. An individual analysis was then done to determine, for each participant, the number of comparisons <=5 mmHg. At least 22 of the 33 participants should have two of their three comparisons <=5 mmHg.

Results: In both studies, the two tested devices passed the first phase of the validation process. For the complete analysis (phase 1 and phase 2), the average differences between the device and mercury sphygmomanometer readings were in the first study for the Seinex SE-9400 device 0.9 /-5.2 and -1.7 /-4.7 mmHg for systolic and diastolic blood pressure, respectively, and -0.2 /-4.5 and -2.0 /-4.8 mmHg for the Microlife BP 3AC1-1 device in the second study. For both devices, readings differing by less than 5, 10 and 15 mmHg for systolic and diastolic blood pressure values fulfill the recommendation criteria of the International Protocol as well as the individual analysis.

Conclusions: The Seinex SE-9400 and the Microlife BP 3AC1-1 devices fulfilled the validation recommendations of the International Protocol.

(C) 2005 Lippincott Williams & Wilkins, Inc.