The Pakistan Palatal Fistula Difficulty Index (PPFDI): Development and Initial Validation of a Novel Scoring Index for Surgical Complexity and Referral Guidance

Palatal fistulae remain the most common complication following cleft palate repair, with recent studies reporting incidence rates ranging from 2% to 35%. Existing classification systems offer limited guidance on surgical complexity or referral pathways. This study developed and validated the Pakistan Palatal Fistula Difficulty Index (PPFDI), a novel scoring system designed to quantify fistula complexity based on 6 domains: location, size, configuration, number of fistulae, recurrence history, and velopharyngeal function. A 3-tiered framework was proposed to guide referral based on complexity level and surgeon experience. Each domain was scored on a 3-point ordinal scale, yielding a total score range of 6 to 18. Content and face validity were established through a modified Delphi process involving 30 expert cleft surgeons, with all 6 domains achieving ≥70% agreement. Inter-rater reliability was assessed using standardized, anonymized clinical case files (n=30) independently scored by 4 senior cleft surgeons. The PPFDI demonstrated strong inter-rater reliability (ICC=0.87, 95% CI: 0.87-0.95), with domain-specific ICCs ranging from 0.78 to 0.92. The mean PPFDI score was 11.1 (SD=2.9), with 43.3% of cases classified as high complexity (score ≥12). Agreement between PPFDI-informed referral tier and clinician-determined referral need was 91.7% (Cohen kappa=0.81), indicating excellent alignment. The PPFDI offers a reliable and clinically meaningful method to stratify palatal fistula complexity and may support more structured decision-making in both low-resource and high-resource settings. Further validation through multicenter studies and correlation with surgical outcomes is warranted to confirm its broader clinical applicability.