Establishing the usefulness of the GO-QOL in a UK hospital-treated population with thyroid eye disease in the CIRTED trial.

Thyroid eye disease (TED) is a potentially sight-threatening and cosmetically disfiguring condition arising in 25-50% of patients with Graves' hyperthyroidism. CIRTED is the first study to evaluate the long-term role of radiotherapy and prolonged immunosuppression with azathioprine in treating TED, one aim of which was to validate the use of the English version of GO-QOL in an UK population with TED. In a three stage design over a 48 week period, the GO-QOL was tested and compared to a general measure of quality of life (WHOQOL-Bref). In stage 1 utilising a standard 14 day test-retest design both GO-QOL subscales achieved Cronbach's alphas demonstrating excellent validity and internal reliability (Visual Function 0.929 and 0.931; Appearance 0.888 and 0.906). In stage 2, Repeated Measures ANOVA demonstrated longitudinal validity, with both subscales of the GO-QOL showing significant change over time (Visual Function, η2 = 0.114, p < .001; Appearance, η2 = 0.069, p < .002). In stage 3 the GO-QOL showed discriminant validity at the week 48 time point, with the visual function subscale being able to detect changes in groups identified by clinicians (using BCCOM ratings of improvement or deterioration), while both subscales could detect group differences when based on participants' subjective ratings of TED noticeability and severity. The results of this project provide support for the English translation of the GO-QOL as an outcome measure for patients with moderately severe active Graves' orbitopathy/TED.