Development and psychometric validation of a patient-reported outcome measure scale for Crohn’s disease anorectal stricture

Abstract Background Anorectal stricture is a severe and debilitating complication of Crohn’s disease (CD). Currently, no specific patient-reported outcome measures (PROMs) exist to assess the severity of anorectal stricture or its impact on the quality of life (QoL) among patients with CD. A new PROM scale has been developed to measure CD anorectal stricture. Methods A 3-phase mixed-methods approach was implemented. Items were generated through a literature review and semi-structured interviews, followed by screening and refinement via pre-surveys and the Delphi method to create an initial scale. Cognitive interviews with patients were conducted to further optimize item content. Psychometric validation included structural validity assessments (comparisons with the hospital anxiety and depression scale [HADS] and the inflammatory bowel disease questionnaire [IBDQ]), as well as reliability and sensitivity evaluations through test–retest analysis. Results The study involved 171 patients with CD-associated anorectal stricture, 13 colorectal surgeons, 3 gastroenterologists, 1 general surgeon, and 1 nurse (all specializing in CD), along with 2 researchers experienced in PROM design, leading to the development of the Crohn’s disease Anorectal Stricture Quality of Life Scale (CDAS-QoL). The scale demonstrated high internal consistency and reliability (Cronbach’s α = 0.92; Guttman split-half = 0.84), good stability (Intraclass correlation coefficient = 0.87), and sensitivity (lower scores in patients with symptom improvement, P = .001; higher scores in those with symptom worsening, P = .03). CDAS-QoL scores were positively correlated with HADS scores (r = 0.66, P < .001) and negatively correlated with IBDQ scores (r = -0.67, P < .001). Conclusions The CDAS-QoL scale is a validated PROM tool applicable to clinical decision-making and trials. It provides an effective instrument to quantify the severity of anorectal stricture in CD and assess its impact on patients’ QoL.