Validation and Clinical Adaptation of a Swedish Version of the Tonsil Outcome Inventory-14 Questionnaire

To translate, culturally adapt, and validate a Swedish version of the Tonsillectomy Outcome Inventory-14 (TOI-14) and to evaluate an extended version including three additional sleep-disordered breathing (SDB) items (TOI-17) among adult tonsil surgery patients.

This prospective multicenter study was conducted across five Swedish ENT departments between 2022 and 2023. One-hundred-and-eight adults scheduled for tonsil surgery and 84 controls without tonsil disease completed the TOI-14, TOI-17, and EQ-5D VAS at baseline and 2 weeks later, and patients repeated the questionnaires 6 months after surgery. Psychometric evaluation included internal consistency, test-retest reliability, convergent and known-groups validity, responsiveness, confirmatory factor analysis (CFA) and exploratory factor analysis (EFA).

At baseline, patients reported markedly higher TOI-14 (39.5 ± 17.8) and TOI-17 (50.7 ± 19.8) scores than controls (3.9 ± 4.5 and 4.9 ± 5.0; p < 0.001). Both instruments showed excellent internal consistency (α = 0.88 and 0.82) and high test-retest reliability (ICC = 0.89 and 0.83). Scores correlated with EQ-5D VAS (r = -0.54 and -0.55; p < 0.001) and improved significantly 6 months postoperatively (p < 0.001). The CFA of the Swedish TOI-14 showed suboptimal fit of the original four-factor model, while EFA of the TOI-17 supported a five-factor solution, with the three SDB items forming a distinct, internally coherent domain (loadings 0.6-0.8).

The Swedish TOI-14 and TOI-17 are valid, reliable, and responsive patient-reported outcome measures for adults with tonsil disease. The extended TOI-17 version adds clinically relevant coverage of sleep-related symptoms, enhancing applicability for both clinical use and registry-based quality assessment.

III-non-randomized controlled cohort.