Adaptation and cross-cultural validation of the Spanish version of the Thyroid-Related Quality-of-Life Patient-Reported Outcome questionnaire

• Published in: Endocrinologia, diabetes y nutricion Vol. 65; no. 9; pp. 500 - 507
• Main Authors: Boronat, Mauro, González-Lleó, Ana, Rodríguez-Pérez, Carlos, Feldt-Rasmussen, Ulla, López-Plasencia, Yaiza, Rasmussen, Åse Krogh, Alberiche-Ruano, María Pino, Hegedüs, Laszlo, Alvarado-Martel, Dácil, Bonnema, Steen Joop, Marrero-Arencibia, Dunia, Groenvold, Mogens, Bjorner, Jakob Bue, Watt, Torquil
• Format: Journal Article
• Language: English
• Published: Spain 01.11.2018
• Subjects: Adult; Cultural Characteristics; Female; Humans; Male; Middle Aged; Patient Reported Outcome Measures; Quality of Life; Self Report; Thyroid Diseases - therapy; Translations; Translation; Cross-cultural validity; Questionnaire; Thyroid disease; Validez transcultural; Enfermedad tiroidea; Calidad de vida; Cuestionario; Traducción; Quality of life
• ISSN: 2530-0172; 2530-0180
• DOI: 10.1016/j.endinu.2018.06.010

The ThyPRO questionnaire is the most widely used tool for measuring quality of life in patients with benign thyroid diseases. The purpose of this study was to adapt and validate a Spanish translation of the ThyPRO and its abbreviated version (ThyPRO-39). Adaptation to the Spanish language was performed using the forward-backward translation method, followed by a pretesting study on five representative patients. The final questionnaire (ThyPROes) was administered to 155 patients with thyroid disorders recruited in a tertiary Spanish hospital. Psychometric properties were evaluated by multitrait scaling and estimation of internal consistency reliability (Cronbach's alpha coefficient). Data from a previous sample of 902 Danish patients were used to analyze differential item functioning (DIF) between the Spanish and the original Danish versions of the questionnaire using ordinal logistic regression. Three of 85 items in ThyPROes and four of the 39 items in ThyPRO-39es lacked convergent validity, while lack of discriminant validity was found for in nine and 14 items of each version respectively. Cronbach's alpha was >0.7 for 12 of 13 scales in the ThyPRO and 10 of 12 scales in the ThyPRO-39es. Eight items in the ThyPROes were flagged with DIF (one with non-uniform DIF), as were two items in the ThyPRO-39es. DIF magnitude was small (explained variance in the item score <3%) in most cases, with a minor impact on scale scores. The Spanish versions of the ThyPRO and ThyPRO-39 show acceptable psychometric properties and good cross-lingual validity, and are suitable for use in clinical studies.