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

## TL;DR

This study validates a Swedish version of the TOI-14 questionnaire and tests an extended version with sleep-related items for use in adult tonsil surgery patients.

## Contribution

The study introduces a culturally adapted and validated Swedish version of the TOI-14 and evaluates an extended TOI-17 with sleep-disordered breathing items.

## Key findings

- The Swedish TOI-14 and TOI-17 showed excellent internal consistency and high test–retest reliability.
- The TOI-17 supported a five-factor model with sleep-disordered breathing items forming a distinct domain.
- Both questionnaires improved significantly 6 months post-surgery and correlated well with quality of life measures.

## Abstract

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.