Adaptation and validation of the Hungarian version of Thyroid-Related Patient-Reported Outcome-39 (ThyPro-39) questionnaire: testing factor structure, known-group validity with the comparison of quality of life in Hashimoto’s thyroiditis and Graves’ disease

BACKGROUND: Living with autoimmune thyroid disease is a longstanding challenge and can seriously affect the quality of life. We aimed to adapt and validate the Hungarian version of the Thyroid-Related Patient-Reported Outcome-39 (ThyPro-39) questionnaire, test its factor structure, and compare two frequent autoimmune thyroid diseases, Hashimoto’s thyroiditis, and Graves’ disease. We tested the factor structure of ThyPro-39 with a series of confirmatory factor analyses (CFAs). To examine the validity of ThyPro-39 and to compare the quality of life of the two groups — Hashimoto’s thyroiditis (N = 240), Graves’ disease (N = 51) — CFA with covariates were used. RESULTS: Our results supported a bifactor model with psychosocial and somatic symptoms as general factors, and 12 symptom-specific factors. Based on the analysis of omega hierarchical indices ranging between 0.22 and 0.66, the specific scales also carry information besides the composite scores and should be used when a more detailed analysis is required. In the multivariate analysis, perceived stress was significantly associated with the general psychosocial factor (β = 0.80), symptom factors (β = 0.34), anxiety (β = 0.43), depressivity (β = 0.37), and emotional susceptibility (β = 0.38) specific factors. Graves’ patients reported more eye symptoms (d = 0.45) and cosmetic complaints (d = 0.40), while Hashimoto patients had more cognitive problems (d = 0.36) and more severe hypothyroid symptoms (d = 0.35). These group differences confirm the known-group validity of the questionnaire. CONCLUSIONS: The validity of the Hungarian version of ThyPRO-39 is supported. We recommend using two composite scores of psychosocial and somatic symptoms and the specific symptoms scores to measure the quality of life in clinical practice and research.