Govert Veldhuijzen

68 Chapter 4 Table 1. In- and exclusion criteria Inclusion criteria Exclusion criteria Adult age Illiteracy for Dutch Referral for complete colonoscopy requiring bowel preparation Audio-visual handicaps Able to provide informed consent Mental disabilities Unwilling to participate No internet access (or relatives with internet access) OUTCOME MEASURES The primary outcome measure is the quality of bowel preparation during endoscopy. Endoscopists are trained to score the bowel preparation with the Boston Bowel Preparation Scale (BBPS). The BBPS is a cumulative score of three bowel segments, ranging from 0-1 “unsatisfactory”, 2-3 “poor”, 4-5 “fair”, 6-7 “good”, and 8-9 “excellent”. Scores of ≥6 are considered adequate. 9,10 As secondary outcomes, the focus is on sickness absence, anxiety, satisfaction and information re-call. Information is also collected on patient activation and health literacy. The cost minimization effect of the intervention is calculated in two ways. The comparison between groups with regard to endoscopy unit costs will be done using a cost-per-visit analysis. The macroeconomic effect of sickness absence is also evaluated, as patients in the intervention group will need less hospital visits. To do so, several items are assessed: socio-economic status, work status and duration of sickness absence, using an adapted iMTA Productivity Cost Questionnaire. 11 Patients anticipating invasive medical procedures often experience anxiety that may exceed their coping mechanisms. Anxiety is assessed at T0 and T1 with the State-Trait Anxiety Inventory (STAI). 12 The STAI is a widely used 20-item self-report instrument with scores ranging from 20 (absence of anxiety) to 80 (high anxiety). Patient satisfaction is scored using two different measures. Patient experience impacts future behaviour and therefore “willingness to return” is assessed at T3, ranging from 1 (extremely unwilling to return) to 10 (extremely willing to return). Furthermore, the Net Promoter Score (NPS) is utilized on the question “Would you recommend this endoscopy unit to your peers?”. Patient’s scores range from 1 (Not at all likely) to 10 (Extremely likely). The NPS will be assessed at T0 and T3 and is calculated as % Promoters (scores 9-10) - % Detractors (scores 1-6). 13 To evaluate patient comprehension of the information in the CBE patients are asked to reproduce elements of the instruction. The patient information re-call is assessed at T1 (before colonoscopy) using a 10-item test, with questions to be answered with “yes” or “no”. The effect of patient education in colonoscopy is influenced by the