Interobserver agreement in duplex scanning for vein grafts

Abstract

Background: although the precision of duplex scanning is of utmost importance in vein-graft surveillance, it has not been properly assessed. This study aims to analyse interobserver agreement on duplex scanning.

Methods: a blinded comparative trial of 69 infrainguinal vein bypass reconstructions. Two consecutive duplex scans were performed by different examiners and duplex ultrasound machines on the same patient. The duplex examinations were also compared with angiography, when available, and clinical follow-up.

Results: interobserver agreement in Kappa statistics was 0.69, signifying "good" agreement between the examinations in detecting haemodynamically significant changes in the grafts. The sensitivity, specificity and accuracy figures compared with a combination of angiography and follow-up data for the two scans were 80%, 91%, 88% and 85%, 93%, 91%, respectively. The limits of agreement were, however, wide for Doppler-derived velocity characteristics.

Conclusion: duplex scanning is an accurate and reproducible method for detecting haemodynamically significant changes in infrainguinal vein grafts.