Reproducibility of ultrasound and CEAP classification to describe possible chronic venous disorders in the legs

Objective. Determine the reproducibility of the Clinical (C) aspect of the Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification and the duplex ultrasound examination (DUS) for describing an individual’s lower extremity chronic venous disorder status. Approach. 33 study participants were examined via CEAP classification and DUS on seven vein segments on two days by two measurement teams (two investigators each). Recommendations for standardization were considered (morning, standing position, manual reflux-provocation manoeuver). One investigator of one measurement team performed the CEAP classification under consistent conditions on both days (test-retest reliability). Additionally, the CEAP classification was performed by two investigators, each from a different measurement team, of the same participant, on the same day (inter-rater reliability). For DUS, test-retest reliability involved one rater evaluating ultrasound images of the same participant taken by the same team across both days. Inter-rater reliability was assessed by having two raters evaluate the same image, while inter-observer reliability was determined by having one rater evaluate the images performed by both teams on the same days. Bland-Altman plots (including systematic bias), weighted kappa, intraclass correlation coefficient, standard error of measurement, and smallest real difference were computed. Main results. Regarding CEAP, classifications agreed with 76% (test-retest, kw=0.71) and 63% (inter-rater, kw=0.63). Difficulties occurred when differentiating between the lowest three C-classes. No systematic errors were found for DUS in all vein segments. Inter-rater reliability in DUS was very high (sem-range=[0.05-0.13]; ICC-range=[0.45-1.00]), compared to test-retest (sem-range=[0.07-0.93]; ICC-range=[-0.21-0.94]) and inter-observer reliability (sem-range=[0.12-0.61]; ICC-range=[-0.01-0.95]). When evaluating whether a reflux was classified pathological, the absolute agreement was very high with ≥94% across all vein segments. Significance. Study results indicated that when considering recommendations for standardization, a high reproducibility of DUS and CEAP classification can be achieved. In future epidemiological field studies, using several raters evaluating the same ultrasound images and finding consensus in case of disagreement seems reasonable.