Comparing translations of the EORTC QLQ-C30 using differential item functioning analyses

Abstract

The European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 is one of the most widely used quality of life instruments for cancer patients. The aim of this study was to assess whether there were linguistic differences in the way an international sample answered the EORTC QLQ-C30 questionnaire. Thirteen translations of the EORTC QLQ-C30, representing 22 countries, were investigated using a database of 27,891 respondents, incorporating 103 separate studies. Differential item functioning (DIF) analyses were conducted using logistic regression to identify items which, after controlling for subscale, were answered differently by language of administration. Both uniform and non-uniform DIF were assessed. Although most languages showed similar results to English, at least one instance of statistically significant DIF was identified for each translation, and a few of these differences were large. In some cases, the patterns were supported by the results of qualitative interviews with bilingual people. Although, overall, there appeared to be good linguistic equivalence for most of the EORTC QLQ-C30 items, several scales showed strongly discrepant results for some translations. Some of these effects are large enough to impact on the results of clinical trials. Based on our experience in this study, we suggest that validation of translations of health-related quality of life instruments should include exploration of DIF.

Differential item functioning (DIF) in the EORTC QLQ-C30: a comparison of baseline, on-treatment and off-treatment data

“…The statistical methodology was identical to that used in the previous papers examining the EORTC QLQ-C30 at baseline [6,7]. Differential item functioning (DIF) analyses using ordinal logistic regression using Stata 10 software were used to investigate whether responses to a particular item differed from other items in the same scale with respect to the translation used after controlling for the overall scale score and adjusting for other variables.…”

“…We previously reported two sets of DIF analyses of a large database of questionnaire responses to the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, a cancer-specific QoL instrument, and examined the evidence for different response patterns by both language of administration [6] and by cultural/geographic grouping [7]. The results suggested that most questionnaire items were answered similarly, regardless of the nationality of the respondent or the translation of the questionnaire used.…”

Portuguese Version of the EORTC QLQ-OES18 and QLQ-OG25 for Health-Related Quality of Life Assessment

“…However, it is important to note that sociodemographic and clinical variables asymmetries may markedly influence HRQoL and response patterns among different populations. 19,20 Such effects may influence decision-making, as the same intervention may have disparate effects among patients of different cultural backgrounds. This insight at least partly explains and justifies the importance of performing the translation of QLQ-OES18 and QLQ-OG25 to the national native language (in this case, Portuguese).…”

Evaluación de la calidad de vida, estado emocional y estrategias de afrontamiento en pacientes con enfermedad neoplásica pulmonar

“…No existe correla- (44) ** No se ha encontrado ninguna investigación en español que aporte datos comparables con nuestra muestra, la única disponible es la de Arrarás, Martínez,Manterola, Salgado, Martínez, Vera, Illarramendi (2005) (45) cuya muestra está compuesta por 97 pacientes con NSCLC pero en estadios muy avanzados (III y IV). *** No se encontraron datos referenciales para los síntomas específicos de cáncer de pulmón medidos con el QLQ-LC13 **** Disnea-C30 hace referencia al síntoma de disnea medido por el cuestionario QLQ-C30 y Disnea-LC13 hace referencia al medido por el QLQ-LC13 ción negativa entre depresión y las escalas sintomáticas.…”