Development of equations for converting random-zero to automated oscillometric blood pressure values

Abstract

Background: This study aimed to collect data to compare blood pressure values between random-zero sphygmomanometers and automated oscillometric devices and generate equations to convert blood pressure values from one device to the other. Methods: Omron HEM-907, a widely used automated oscillometric device in many epidemiologic surveys and cohort studies, was compared here with random-zero sphygmomanometers. In total, 201 participants aged 40-79 years (37% men) were enrolled and randomly assigned to one of two groups, with blood pressure measurement first taken by automated oscillometric devices or by random-zero sphygmomanometers. The study design enabled comparisons of blood pressure values between random-zero sphygmomanometers and two modes of this automated oscillometric device (automated and manual), and assessment of effects of measurement order on blood pressure values. Results: Among all participants, mean blood pressure levels were the lowest when measured with random-zero sphygmomanometers compared with both modes of automated oscillometric devices. Several variables, including age and gender, were found to contribute to the blood pressure differences between random-zero sphygmomanometers and automated oscillometric devices. Equations were developed using multiple linear regression after taking those variables into account to convert blood pressure values by random-zero sphygmomanometers to automated oscillometric devices. Conclusions: Equations developed in this study could be used to compare blood pressure values between epidemiologic and clinical studies or identify shift of blood pressure distribution over time using different devices for blood pressure measurements.