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.
Competing Interests: Competing interests: KS, PJT and SOA have received honoraria from Takeda for sitting on an advisory board. PJT has received honoraria from Takeda for speaking at a symposium. LD: speaker fees from Janssen and AbbVie; consultancy fees from GL Assessments. CN: speaker’s fees from Takeda, Tillots Pharma and Ferring Pharmaceuticals. ALH has served as a consultant, advisory board member or speaker for AbbVie, Atlantic, Bristol Myers Squibb, Celltrion, Falk, Ferring, Janssen, MSD, Napp Pharmaceuticals, Pfizer, Pharmacosmos, Shire and Takeda. She also serves on the global steering committee for Genentech.
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