Methodological insights and correlations of short-term BP variability indices

Blood Pressure Variability (BPV) is an independent risk factor for cardiovascular events. Short-term indices of BPV, such as standard deviation (SD), coefficient of variation (CV), average real variability (ARV), and Time Rate Index (TRI) are calculated using blood pressure (BP) measurements from 24-hour ambulatory blood pressure monitoring (ABPM). Although these indices have distinct units and amplitudes, their relationships have not been thoroughly investigated. This study aims to explore the correlation between the SD, CV, ARV, and TRI indices of short-term BPV.

Data were collected during the baseline evaluation of hypertensive participants with obstructive sleep apnoea in a randomised controlled trial. Systolic BPV indices were measured using 24-hour systolic ABPM. Pearson correlation (r) and intraclass correlation (ICC) for consistency were calculated among the BPV indices.

Sixty-five participants aged ≥40 years were evaluated. SD, CV, and ARV showed high linear correlations, and their ICCs indicated moderate consistency between SD and CV, and between CV and ARV. In contrast, TRI exhibited weak correlations and no ICC consistency with the other indices.

The strong linear correlations and moderate-to-high ICC consistency among SD, CV, and ARV suggest these indices may be used interchangeably in studies of short-term BPV and cardio-vascular outcomes. TRI, however, reflects a distinct construct and should be evaluated separately when assessing its prognostic value.