Page 152 - Demo

Chapter 6150Study 2: Content validityContent and face validity of the questionnaire were ensured by involving TSC experts in the field, including individuals with TSC and representatives in focus group interviews and the expert multidisciplinary team. In this way, the instrument’s content validity was verified by all major stakeholders. We recruited eleven participants (five self-rated and six proxy-rated) in the Netherlands, ten in Belgium (five self-rated and five proxy-rated), and ten participants in the United States (five self-rated and five proxy-rated). Feasibility: It took participants 16.53 (±5.00, range 10-30) minutes to complete the questionnaire. Participants preferred a digital version and the lay-out was assessed as clear by 85.7% of the participants and 14.3% somewhat agreed. Comprehensibility: 81% of the participants found the instructions, the items and the formulations clear and 19% somewhat agreed. One participant indicated difficulties when complaints are always present. Small suggestions were made for clarification. 85.7% of the examples provided were clear and understandable. 66,7% indicated clear response options. Feedback included lack of the response option ‘not applicable’ in the selfreport version and difficulty to estimate the applicability of ‘not applicable’ or ‘do not know’ for the proxy-report. 85.7% of the participants agreed on the sequence of items. Relevance and comprehensiveness: Participants did not indicate other items or complaints and agreed on comprehensiveness, completeness, and relevance. All relevant questions were included, although not all questions were applicable to the different levels of functioning. Study 3: Structural validity, internal validity, construct validityE-mails with access to the questionnaires were sent to 210 participants, with a response rate of 78%. In total 163 participants completed the TSC-PROM, of whom 114 participants filled in the complete questionnaire battery (85% of self-reporting participants and 46% of proxy-reporting participants). Six and thirteen self-reporting participants and 27 and 36 proxy-reporting participants did not fill out the SF-36 and ASEBA questionnaires, respectively. Annelieke Muller sHL.indd 150 14-11-2023 09:07