http://repub.eur.nl/res/aut/28089/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/32917/ 2012-06-29T00:00:00Z Background: Although cancer-specific Health-related Quality-of-Life measures are commonly included in randomized clinical trials or other prospective non-randomized clinical studies, it is rare that preference-based instruments are used, which allow the calculation of a Utility weight suitable for estimating Quality-adjusted Life-Years gained. Objective: To test the external validity of a previously published mapping algorithm to transform the EORTC QLQ-C30 questionnaire responses into EQ-5D-derived utilities by predicting EQ-5D utilities from QLQ-C30 scores. Study design and methods: Comparative retrospective data analysis of four multicentre, prospective clinical trials in Breast, Multiple Myeloma, Non-Hodgkin Lymphoma and Non-Small-Cell Lung cancer patients with, respectively, 219, 172, 132 and 172 patients. Regression analysis of individual pairs of EQ-5D and QLQ-C30 scores. Results: Although the internal predictive power of a previously published mapping equation was high, its external validity when tested on a set of unrelated external data sets in other cancers proved to underestimate both the mean and variance of the mapped EQ-5D utilities. Furthermore, it appears that the relationship between QLQ-C30 scores and EQ-5D values is not stable across the different data sets. Conclusions: Validation of the proposed algorithm in other external clinical data sets should be encouraged as well as the application of other more complex mapping methods to enhance accuracy of mapping. In the meanwhile, direct mapping from QLQ-C30 profiles to EQ-5D utilities using published algorithms should be performed with reservations. http://repub.eur.nl/res/pub/22910/ 2011-01-01T00:00:00Z Abstract: The Overall Assessment of the Speaker’s Experience of Stuttering for adults (OASES-A; Yaruss & Quesal, 2006, 2010) is a patient-reported outcome measure that was designed to provide a comprehensive assessment of “the experience of the stuttering disorder from the perspective of individuals who stutter” (Yaruss & Quesal, 2006, p.90). This paper reports on the translation process and evaluates the psychometric performance of a Dutch version of the OASES-A. Translation of the OASES-A into Dutch followed a standard forward and backward translation process. The Dutch OASES-A (OASES-A-D) was then administered to 138 adults who stutter. A subset of 91 respondents also evaluated their speech on a 10-point Likert scale. For another subset of 45 respondents, a clinician-based stuttering severity rating on a 5-point Likert scale was available. Thirty-two of the respondents also completed the Dutch S-24 scale (Brutten & Vanryckeghem, 2003). The OASES-A-D showed acceptable item properties. No ceiling effects were observed. For 30 out of 100 items, most of which were in Section IV (Quality of Life), floor effects were observed. Cronbach’s alpha coefficients for all sections and subsections surpassed the 0.70 criterion of good internal consistency and reliability. Concurrent validity was moderate to high. Construct validity was confirmed by distinct scores on the OASES-A-D for groups with different levels of stuttering severity as rated by the speakers themselves or by clinicians. These results suggest that the OASES-A-D is a reliable and valid measure that can be used to assess the impact of stuttering on Dutch adults who stutter.