Reliability of Laser Doppler Flowmetry Curve Reading for Measurement of Toe and Ankle Pressures: Intra- and Inter-observer Variation

C. HØYER; J.P.D. PALUDAN; S. PAVAR; J.A. BIURRUN MANRESA; L.J. PETERSEN

EUROPEAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY : THE OFFICIAL JOURNAL OF THE EUROPEAN SOCIETY FOR VASCULAR SURGERY.

W B SAUNDERS CO LTD

Lugar: Londres; Año: 2014 vol. 47 p. 311 - 318

1078-5884

ObjectivesTo assess the intra- and inter-observer variation in laser Doppler flowmetry curve reading for measurement of toe and ankle pressures.MethodsA prospective single blinded diagnostic accuracy study was conducted on 200 patients with known or suspected peripheral arterial disease (PAD), with a total of 760 curve sets produced. The first curve reading for this study was performed by laboratory technologists blinded to clinical clues and previous readings at least 3 months after the primary data sampling. The pressure curves were later reassessed following another period of at least 3 months. Observer agreement in diagnostic classification according to TASC-II criteria was quantified using Cohen´s kappa. Reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland?Altman analysis.ResultsThe overall agreement in diagnostic classification (PAD/not PAD) was 173/200 (87%) for intra-observer (κ = .858) and 175/200 (88%) for inter-observer data (κ = .787). Reliability analysis confirmed excellent correlation for both intra- and inter-observer data (ICC all ≥.931). The coefficients of variance ranged from 2.27% to 6.44% for intra-observer and 2.39% to 8.42% for inter-observer data. Subgroup analysis showed lower observer-variation for reading of toe pressures in patients with diabetes and/or chronic kidney disease than patients not diagnosed with these conditions. Bland?Altman plots showed higher variation in toe pressure readings than ankle pressure readings.ConclusionsThis study shows substantial intra- and inter-observer agreement in diagnostic classification and reading of absolute pressures when using laboratory technologists as observers. The study emphasises that observer variation for curve reading is an important factor concerning the overall reproducibility of the method. Our data suggest diabetes and chronic kidney disease have an influence on toe pressure reproducibility.