Inter-Observer Agreement of the Paris and the Simplified Classifications of Superficial Colonic Lesions: A Western Study

Aims The Paris classification of superficial colonic lesions is widely adopted, but a simplified description which subgroups the shape into pedunculated, sessile/flat and depressed lesions has been proposed recently. To evaluate accuracy and inter-rater agreement among 13 Western endoscopists for the two classification systems.

Methods Seventy video clips of superficial colonic lesions were classified according to the two classifications, and their size estimated. The inter-observer agreement for each classification was assessed using both Cohen k and AC1 statistics. Accuracy was taken as the concordance between the standard morphology definition and that made by participants. Sensitivity analyses investigated agreement between trainees (T) and staff members (SM), simple or mixed lesions, distinct lesion phenotypes, and for laterally spreading tumors (LSTs).

Results Overall, the inter-observer agreement for the Paris classification was substantial (κ=0.61; AC1=0.66), with 79.3 % accuracy. Between SM and T, the values were superimposable. For size estimation the agreement was 0.48 by the κ-value, and 0.50 by AC1. For single or mixed lesions κ-values were 0.60 and 0.43, respectively; corresponding AC1 values were 0.68 and 0.57. Evaluating separately the several different polyp subtypes, agreement differed significantly when analyzed by the k-statistics (0.08-0.12) or the AC1 Statistics (0.59-0.71). Analyses of LSTs provided a κ-value of 0.50 and an AC1 score of 0.62, with 77.6 % accuracy. The simplified classification outperformed the Paris classification: κ=0.68, AC1=0.82, accuracy=91.6 %.

Conclusions Agreement is often measured with Cohen’s κ, but we documented higher level of agreement when analyzed with AC1 statistic. The level of agreement was substantial for the Paris classification, and almost perfect for the simplified system.

Citation: Cocomazzi F, Gentile M, Perri F et al. eP173 INTER-OBSERVER AGREEMENT OF THE PARIS AND THE SIMPLIFIED CLASSIFICATIONS OF SUPERFICIAL COLONIC LESIONS: A WESTERN STUDY. Endoscopy 2021; 53: S153.

Publication History

Article published online:
19 March 2021