Bridging and Validation of the Specific Graves Ophthalmopathy Quality of Life Questionnaire With Health State Utility Values

Abstract

Objective: In thyroid eye disease (TED), inflammation and expansion of orbital muscle and periorbital fat result in diplopia and proptosis, severely impacting patient quality of life (QOL). The reported health state utility (HSU) scores, which are QOL measures, allow quantification of TED impact and improvement with therapies; however, no current QOL instrument has been validated with HSU scores for TED. Here, we used the disease-specific Graves Ophthalmopathy Quality of Life (GO-QOL) questionnaire and HSU scores to validate QOL impact.

Methods: The GO-QOL scores from patients in 2 randomized, masked, placebo-controlled teprotumumab trials (N=171) were compared with 6 HSU values based on severity of proptosis/diplopia in those studies. Patient GO-QOL and HSU scores were compared at baseline and after 6-month treatment via regression analyses. GO-QOL and HSU scores were correlated for validation and quantification of QOL impact by severity state and to estimate quality-adjusted life year improvement.

Results: GO-QOL scores were correlated with TED severity, indicating that worse severity was associated with lower (worse) GO-QOL scores. Less severe health states were represented by higher (better) GO-QOL scores. Importantly, GO-QOL scores were positively correlated with utility scores of the 6 health states, allowing for conversion of the GO-QOL scores to utility scores. A positive (improved) 0.013 utility change was found for each 1-point (positive) improvement in GO-QOL score produced by teprotumumab versus placebo.

Conclusion: Patients with moderate-to-severe active TED health states demonstrate increasing TED severity associated with declining utility values and worsening GO-QOL scores. These results indicate that the GO-QOL scores can be used to bridge to the HSU scores for benefit quantification.

Keywords: GO-QOL; health state utility; thyroid eye disease; utility.