Page 147 - Demo

Development and validation of the TSC-PROM1456questionnaire by completing a feedback form by using the ‘Retrospective Verbal Probing’ technique,41 and a topic guide by interviewers who were trained specifically for the study. The feedback form consisted of questions on relevance, comprehensiveness, comprehensibility, and practical issues such as ease of use and lay-out. The TSC-PROM was considered feasible when time to complete was below thirty minutes. Comprehensibility was considered sufficient when at least 75% of the participants agreed on clarity of the instructions, items, formulations, response options, and sequence of items. Also, individuals with TSC were asked whether there were missing, redundant, or unclear items, as well as the most important TSC manifestations, to identify possible missing themes. Cognitive debriefing was performed to refine further and focus the items of the questionnaire and to gain insight into the instrument’s practical applicability. Group meetings and interviews were recorded and transcribed verbatim. Two researchers were involved in the analysis. The pilot phase concluded with a final discussion with the expert group about whether each item was relevant for the construct of interest and comprehensiveness of the TSC-PROM. .Study 3: Structural validity, internal consistency, construct validityProcedureE-mails with an invitation link and login code granting access to the questionnaires were sent to participants after answering a question about whether the questionnaire will be filled out by either the individual with TSC themselves or a proxy when (assisted) self-report was not possible, as indicated by the primary caregiver, legal representative or clinician. A proxy who declared to know the individual with TSC well, such as the legal representative or primary caregiver, was allowed to fill out the questionnaires.ParticipantsTo be eligible for participation in this study, adults (18 years or older) with a definite diagnosis of TSC, molecularly or clinically confirmed according to recent recommendations,1,2 should be English or Dutch-speaking. Participants were recruited from the outpatient TSC clinics at the University Medical Center of Utrecht (Utrecht, the Netherlands), Erasmus Medical Center (Rotterdam, the Netherlands), the University Hospital of Brussels (Brussels, Belgium), Le Bonheur Children’s Hospital Memphis (Memphis, Annelieke Muller sHL.indd 145 14-11-2023 09:07