Validation of US evaluation of ulcerative colitis activity.

This study was aimed at validating the inter-rater grading agreement for assessing disease activity in patients with established ulcerative colitis (UC) using transabdominal ultrasonography (US) versus colonoscopy (CS). Fifty-seven patients underwent US and CS at four facilities. UC disease activity was assessed using the original US grading system and CS Matts classification. Initially, the US and CS grades were assessed at each examining facility, and still images and movie clips were re-assessed at the central facility. Grading agreement between the examining and central facilities was evaluated. Grading agreement for US and CS were 0.75 and 0.72 in all segments and 0.82 and 0.70 in the maximum grade of each patient, respectively (all p < 0.001). US grading agreement was "almost perfect" for the maximum grade and "moderate" to "substantial" for other assessments. The inter-rater US grading agreement was good and not inferior to that of CS for evaluating UC disease activity.