Govert Veldhuijzen

152 Chapter 8 METHODS The English version of the GESQ was used with permission of the authors. 11 The translation of this questionnaire was performed using backward and forward translation. 12,13 The questions were first translated into Dutch by a Dutch native speaker. We strived to provide a translation which most closely resembles the original instrument. The result of the translation was discussed with the expert panel. This panel was composed by four members of our research team (AvE, CR, GV, MdJ). As a result, some minor adjustments were made. Then the questionnaire was translated backwards into English by a different translator, being an English native speaker. Next, the original questionnaire was compared with the backward translation in another expert panel meeting. Finally, the 1.0 version of D-GESQ was fine-tuned based on the outcomes of this session. Patients who had undergone upper endoscopy or colonoscopy were recruited from the outpatient’s clinic of the Radboudumc, Nijmegen The Netherlands, for the internal validation process. A member of the research team asked patients to complete the 1.0 version of the questionnaire. We applied the think-aloud method, meaning that while performing a task, patients verbalize whatever crossed their minds. 14 Based on the data coming from the original development of the GESQ we estimated that 20 patients would be sufficient to obtain data saturation. The data saturation point is classified as the point at which the possibility of collecting new additional information has been reached. 15 Main goal of the think-aloud method was to evaluate whether each question was interpreted correctly. General comments were also collected. The aim was to create a questionnaire which was clear to all patients and that covered all aspects of patient satisfaction. The results of these conversations were analysed, and questions were rewritten where necessary, resulting in a 2.0 version. The 2.0 version of the questionnaire in Dutch (see Supplementary Material) was embedded in the online computer based education (CBE) platform used in our endoscopy unit. 16 This platform acts as a nexus between the endoscopy department and the patient throughout the scheduling and patient education process prior to endoscopy. 17 The D-GESQ was timed to be sent out automatically, 30 days after patients had been subjected to upper endoscopy or colonoscopy. This interval was chosen because it allows additional patient reported evaluation of adverse events. The 30 day period is the chosen interval in the quality measure for colonoscopies performed in the Dutch colorectal cancer screening programme. 4 There were no reminders sent by email.