Background: A high percentage of hypertensive patients present an arm circumference of over 32 cm; the use of a large cuff is therefore recommended. Validation studies are usually performed in the general population using a standard-size cuff. The aim of this study was to assess the accuracy of the Omron M7 device in a population with an arm circumference ranging from 32 to 42 cm.
Design: A validation study was performed according to the International Protocol of the European Society of Hypertension. This protocol is divided into two phases: the first phase is performed on 15 selected participants (45 pairs of blood-pressure measurements); if the device passes this phase, 18 supplementary participants are included (54 pairs of blood-pressure measurements), making a total number of 33 participants (99 pairs of blood-pressure measurements), on whom the analysis is performed.
Methods: For each participant, four blood-pressure measurements were performed simultaneously by two trained observers, using mercury sphygmomanometers fitted with a Y tube; the measurements alternated with three by the test device. The difference between the blood-pressure value given by the device and that obtained by the two observers (mean of the two observations) was calculated for each measure. The 99 pairs of blood-pressure differences were classified into three categories (<or=5, <or=10 and <or=15 mmHg). The number of differences in each category was compared with the number required by the European Society of Hypertension protocol.
Results: The Omron M7 device passed the first and the second phases of the validation process. The average differences between the two observers were 1.5+/-3.2 and -0.5+/-2.2 mmHg for systolic blood pressure and diastolic blood pressure, and those between the device and the mercury sphygmomanometer were -1.6+/-6.7 for systolic blood pressure and -0.12+/-4.0 mmHg for diastolic blood pressure Readings that differ by less than 5, 10 and 15 mmHg for systolic blood-pressure and diastolic blood-pressure values fulfill the recommendation criteria of the European Society of Hypertension protocol.
Conclusions: The Omron M7 (HEM-780-E) device fulfilled the validation criteria of the international protocol in a population with an arm circumference ranging from 32 to 42 cm.