Augmenting inter‐rater concordance of radiologic extranodal extension in HPV‐positive oropharyngeal carcinoma: A multicenter study

Objectives To assess intra‐ and inter‐institutional concordance and identify methods to increase precision in radiologic extranodal extension (rENE) ascertainment in HPV+ oropharyngeal carcinoma. Methods Six radiologists, blinded to clinical outcomes, from three centers assessed rENE in two phases: Phase‐I (20 cases) utilized each individual's a priori appreciation of the literature. Phase‐II (30 additional cases) was performed after deliberating experience and consolidating operating definitions. Intra‐ and inter‐institutional Kappa were calculated at >50% and >75% certainty levels, respectively. Results The Phase‐I intra‐institutional kappa was 0.76, 0.32, and 0.44 at >50% certainty and improved to 0.89, 0.61, and 0.66 at >75% certainty. Inter‐institutional Fleiss' kappa also improved with higher certainty (from 0.40 to 0.57, p = 0.039). The Phase‐II inter‐rater kappa was significantly higher than Phase‐I at the same certainty level (both p