Development and initial psychometric validation of a patient-reported outcome measure for Crohn's perianal fistula: the Crohn's Anal Fistula Quality of Life (CAF-QoL) scale

Introduction Crohn's perianal fistulas are challenging for patients and clinicians. Many do not respond to available treatments and despite recommendations by a global consensus, there are currently no specific patient-derived quality of life tools to measure response to treatment. We present a new validated patient-reported outcome measure (PROM) for this complicated disease phenotype. Methods A draft questionnaire was generated using unstructured qualitative patient interviews on the experience of living with Crohn's perianal fistula, a nationwide multidisciplinary consensus exercise, a systematic review of outcomes assessing medical/surgical/combined treatment and a patient and public involvement day. Psychometric properties were assessed including construct validity (by comparison with the Hospital Anxiety and Depression Scale (HADS) and the UK Inflammatory Bowel Disease Questionnaire (UK-IBDQ)), and reliability and responsiveness was assessed by test-retest analysis. Results Data from 211 patients contributed to development of a final 28-item questionnaire. The Crohn's Anal Fistula Quality of Life (CAF-QoL) demonstrated good internal consistency (Cronbach's alpha 0.88), excellent stability (intraclass correlation 0.98) and good responsiveness and construct validity, with positive correlation with the UK-IBDQ and HADS. Conclusion The CAF-QoL scale is ready for use as a PROM in research and clinical practice. It complements objective clinical evaluation of fistula by capturing impact on the patient.

Automated summary

Crohn's perianal fistulas present challenges for patients and clinicians, with no specific patient-derived quality of life tools to measure treatment response. The newly developed Crohn's Anal Fistula Quality of Life (CAF-QoL) scale has shown good internal consistency, stability, responsiveness, and construct validity, complementing objective clinical evaluation of the disease.