Validity and reliability of the TED-QOL: a new three-item questionnaire to assess quality of life in thyroid eye disease

Aim To develop and test a user-friendly questionnaire for rapidly assessing quality of life (QOL) in thyroid eye disease (TED). Methods A three-item questionnaire, the TED-QOL, was designed and compared to the 16-item Graves Ophthalmopathy (GO)-QOL and the nine-item GO-Quality of Life Scale (QLS). 100 patients with TED were administered all three questionnaires on two occasions. Results were compared to clinical severity scores (Vision, Inflammation, Strabismus, Appearance (VISA) classification). Main outcomes were construct and criterion validity, test-retest reliability, duration, comprehension and completion rates. Results TED-QOL correlated strongly with the other questionnaires for corresponding items (Pearson correlation: appearance 0.71, 0.62; functioning 0.69, 0.66; overall QOL 0.53). Test-retest analysis demonstrated good reliability for all three questionnaires (intraclass correlations: TED-QOL 0.81, 0.74, 0.87; GO-QOL 0.81, 0.82; GO-QLS 0.74, 0.86, 0.67). TED-QOL was significantly faster to complete (1.6 min vs GO-QOL 3.1 min, GO-QLS 2.7 min, p<0.0001) and had a higher completion rate (100% vs GO-QOL 78%, GO-QLS 94%). There was only moderate correlation between items on all three questionnaires and VISA scores. Conclusion The TED-QOL is rapid and easy to complete and analyse and has similar validity and reliability to longer questionnaires. All questionnaires showed only moderate correlation with disease severity, emphasising the discrepancy between objective and subjective assessments and the importance of measuring both.