Capturing quality of life in pouch anal and vaginal fistula: development of PAVF-QoL-14, a patient-reported outcome measure.

INTRODUCTION

Perianal pouch fistula can significantly affect quality of life, yet no disease-specific patient reported outcome measure (PROM) exists. We have developed and validated a 14-item PROM-the Pouch Anal and Vaginal Fistula Quality of Life scale (PAVF-QoL-14).

METHODS

COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidance for PROM development was used to develop and validate PAVF-QoL-14. A systematic literature review and semi-structured patient interviews (n = 14) identified key domains. Cognitive interviews and item-level content validity index with experts refined the draft questionnaire. Psychometric evaluation included principal component analysis (PCA), internal consistency testing, and construct validity assessment against Hospital Anxiety and Depression Scale (HADS) and Short-Form 12 (SF-12). Test-retest analysis was performed on 76 patients.

RESULTS

An initial 34-item draft scale was generated and refined through cognitive interviews (n = 10) and psychometric testing (n = 76). Flesch readability score was 63%. Kaiser-Meyer-Olkin test confirmed sampling adequacy (KMO = 0.905), and correlations between items were found significant using Bartlett's test of sphericity (p < 0.001). Four domains (symptoms, discharge, faecal incontinence, and future concerns) were extracted, explaining 63.7% of the total variance. Following stepwise regression, a 14-item short-form was developed, demonstrating excellent internal consistency (Cronbach's α = 0.920). Responsiveness was good (effect size 0.77), and test-retest reliability demonstrated excellent stability (ICC = 0.924). Construct validity was supported by moderate-to-strong correlations with HADS (r = 0.589, p < 0.001) and SF-12 (r = 0.525, p < 0.001). The final questionnaire generates scores ranging from 14 to 70, with higher scores indicating greater fistula-related impairment in quality of life.

CONCLUSION

PAVF-QoL-14 provides a concise, validated, and disease-specific measure of quality of life for pouch-related fistula and shows strong potential for use in clinical practice and clinical trials.