Psychometric evaluation of the Urgency NRS as a new patient-reported outcome measure for patients with ulcerative colitis

Abstract

Abstract Background The Urgency Numeric Rating Scale (NRS) was developed as a content-valid single-item patient-reported outcome measure to assess severity of bowel urgency. Here, we evaluated the psychometric properties of the Urgency NRS. Methods Data were from a multicenter, randomized, placebo-controlled phase 3 trial in adults with moderately to severely active ulcerative colitis (NCT03518086). Patients completed the Urgency NRS using a daily electronic diary, from which weekly average Urgency NRS scores were calculated. Test–retest reliability, known-groups validity, construct validity, responsiveness, and score interpretation were assessed using the modified Mayo score, Inflammatory Bowel Disease Questionnaire (IBDQ), Patient Global Rating of Severity (PGRS), Patient Global Rating of Change (PGRC), and Geboes score. Results The study sample comprised 1,162 participants (40.2% female). Mean Urgency NRS score was higher (worse) at baseline than at week 12 (6.2 vs. 3.7). Test–retest reliability was strong, with intra-class correlation coefficients of 0.76–0.89. Baseline least-square mean Urgency NRS score was higher for participants with a PGRS score greater than the median (worse symptoms) than for those with a PGRS score less than or equal to the median (7.5 vs. 5.4; p < 0.0001), indicating good known-groups validity. Urgency NRS score was moderately correlated with IBDQ total and domain scores, PGRS, PGRC, and modified Mayo stool frequency, establishing its convergent validity. Correlations were weak for Geboes score and weak to moderate for modified Mayo endoscopic subscore and modified Mayo rectal bleeding, indicating that the Urgency NRS also had discriminant validity. Patients achieving clinical remission, clinical response, IBDQ remission, and PGRS score improvement showed significantly greater improvement on the Urgency NRS (p < 0.0001 for all), demonstrating responsiveness to change. A ≥ 3-point improvement in Urgency NRS score represented a meaningful improvement in bowel urgency and an Urgency NRS score of ≤ 1 point represented a bowel urgency remission threshold that was closely associated with clinical, endoscopic, and histologic remission. Conclusions The Urgency NRS is a valid and reliable patient-reported outcome measure that is suitable for evaluating treatment benefits in clinical trials in patients with moderately to severely active ulcerative colitis.