Test Re-Test Reliability of Brachial Artery Flow-Mediated Dilation in Healthy Adults

Abstract

Ultrasonographic assessment of flow mediated dilation (FMD) is a valuable noninvasive measurement of endothelial function; it has been shown to be a useful prognostic tool for cardiovascular disease risk. However, reproducibility of FMD in the literature varies greatly (Coefficient of Variations (CV) =2-84%). Purpose: Therefore the aim of this study was to examine the test-retest reliability and day-to-day variability in measurements of FMD in 14 healthy young adults. Methods: FMD was analyzed on three different occasions within a 21 day period for each subject after a ≥ 8 hour overnight fast. Ultrasound derived diameter of the brachial artery was measured at baseline (resting condition) and immediately following reactive hyperemia. FMD was calculated as percent change in diameter from baseline. Results: FMD measurements for interday comparisons demonstrated moderate to strong reliability (intraclass correlation coefficient [ICC] = 0.73, P=0.004; CV = 24.7%). Additionally, reliability for average baseline diameter (CV = 4.5%; ICC = 0.95; p<0.001) and max hyperemic diameter (CV = 4.8%; ICC = 0.93, p<0.001) were very strong. Conclusion: These results suggest that FMD can be measured with adequate reproducibility in healthy adults when following a strict protocol.