Page 146 - Demo

Chapter 6144The preliminary test versions of the questionnaires for individuals with TSC and proxies were reviewed and refined by the expert group. Based on their expertise, topics were added, altered, or removed. TranslationTwo questionnaires were initially developed in the Dutch language in the Netherlands and Belgium. After professional expert translation into English using back and forward translation, a pilot was performed in the United States with English-speaking individuals with TSC and representatives (at least five self-rated and five proxy-rated) in order to broaden the population. The pilot concluded with a discussion with the expert group, and final revisions were made to the questionnaires with a final consensus. Cognitive interview study (comprehensibility)A cognitive interview study was performed in all participating languages (Dutch and English) to assess the comprehensibility of the questionnaire. Other than those who participated in the concept elicitation, individuals with TSC from the participating outpatient clinics were asked to provide qualitative feedback on the questionnaire. At least five participants were recruited per type of report (self or proxy) with a definite diagnosis of TSC2 and a minimum age of 18 years for each participating country (the Netherlands, Belgium, and the United States), with an aimed minimum of 30 participants. We aimed to include participants with different ages, gender, and education to have a sample representing the target population. Individuals with TSC were excluded when an additional genetic disorder to TSC was diagnosed. The cognitive interview study included the ‘Think aloud’ method33,40,41 and the ‘Retrospective Verbal Probing’ technique to assess comprehensibility of the instructions, all items, response options, and recall period.41Study 2: Content validityFace and content validity was examined by the multidisciplinary expert group and with the abovementioned participants from the cognitive interview study in the Netherlands, Belgium, and the United States; these countries were selected by convenience. Individuals with TSC from the participating outpatient clinics were asked to provide feedback on the digital Annelieke Muller sHL.indd 144 14-11-2023 09:07