ACCURACY AND REPRODUCIBILITY OF 30 DEVICES FOR SELF-MEASUREMENT OF ARTERIAL BLOOD-PRESSURE

Thirty commercially available noninvasive devices for self-measurement of blood pressure were tested for accuracy and reproducibility agains t intraarterial measurement in 15 normotensive and 15 hypertensive sub jects. For reference to outpatient measurements, a standard sphygmoman ometer was included. Analysis of the data for any device was performed according to a statistical model in which two types of errors, repres enting accuracy and reproducibility, were distinguished: offset (mean difference between intraarterial measurement and device) and standard deviation (comprising intraindividual and interindividual variability) . Linearity of the devices was analyzed by linear regression with intr aarterial measurement as independent variable. The average offset of a ll tested devices amounted to 11.7 mm Hg (ranging from -0.2 to 21.4 be tween instruments) for systolic blood pressure and -1.6 mm Hg (range - 11.4 to 8.1) for diastolic blood pressure. The standard deviation betw een instruments ranged from 7.0 to 15.4 mm Hg for systolic and from 3. 3 to 16.0 mm Hg for diastolic blood pressure. Except for the devices b ased on the oscillometric principle, most (semi-) automated devices de monstrated a variability similar to the mercury sphygmomanometer (offs et = 14.3 for systolic and 0.1 mm Hg for diastolic pressure; standard deviation = 7.5 for systolic and 5.6 mm Hg for diastolic blood pressur e). Devices based on the oscillometric principle had a significantly l arger variability. It is concluded that new devices should be tested f or accuracy and reproducibility before application for clinical use. B lood pressure measurements from instruments with larger offset are onl y comparable to values from other instruments after rescaling in accor dance with their offset.