Derivation of a measure of systolic blood pressure mutability: a novel information theory-based metric from ambulatory blood pressure tests.

We provide ambulatory blood pressure (BP) exams with tools based on information theory to quantify fluctuations thus increasing the capture of dynamic test components. Data from 515 ambulatory 24-hour BP exams were considered. Average age was 54 years, 54% were women, and 53% were under BP treatment. The average systolic pressure (SP) was 127 ± 8 mm Hg. A data compressor (wlzip) designed to recognize meaningful information is invoked to measure mutability which is a form of dynamical variability. For patients with the same average SP, different mutability values are obtained which reflects the differences in dynamical variability. In unadjusted linear regression models, mutability had low association with the mean systolic BP (R(2) = 0.056; P < .000001) but larger association with the SP deviation (R(2) = 0.761; P < .001). Wlzip allows detecting levels of variability in SP that could be hazardous. This new indicator can be easily added to the 24-hour BP monitors improving information toward diagnosis.