Govert Veldhuijzen

94 Chapter 5 Table 1. Baseline Characteristics Per-protocol population Nurse counselling Computer Based Education Nurse versus Computer Based Education (statistical test) Gender n (%)  Male  Female 106 (48.8) 111 (51.2) 129 (46.1) 151 (53.9) p = 0.539 (Chi-Square) Age (mean, SD) 56 years, 14.5 56 years, 14.5 p = 0.797 (t-test) Ethnicity n (%)  Native Dutch  Other 194 (89.4) 22 (10.1) 242 (86.4) 30 (10.7) p = 0.764 (Chi-Square) Educational level† n (%)  Low  Middle  High 27 (12.4) 121 (55.8) 69 (31.8) 41 (14.6) 154 (55.0) 85 (30.4) p = 0.980 (Chi-Square) Prior experience with colonoscopy n (%) 101 (46.8) 140 (51.5) p = 0.301 (Chi-Square) † Highest completed educational level was split into three levels where ‘low’ comprised no education through to lower secondary education, ‘middle’ comprised upper secondary and middle vocational education, and ‘high’ comprised higher vocational and tertiary education Primary endpoint BBPS scores were collected for all 684 patients. In the ITT and PP population, mean BBPS scores in both groups exceeded the threshold of 6 considered adequate. In the PP population, the mean BBPS in the nurse counselling group was 8.00 (95% CI 7.78; 8.21), comparable to that of the CBE group at 7.81 (95% CI 7.62; 8.00), p=0.207. We subsequently calculated the risk to obtain an adequate BBPS (> 6). In the ITT population the CBE group, 93.4% of patients, reached an adequate BBPS score, compared to 95.8% assigned to the nurse counselling group. The 95% confidence interval of the relative risk difference (–2.4%) was –5.8% to 0.9%, which was within the prespecified non-inferiority margin of 10%. In the PP population the CBE group, 93.2% of patients reached an adequate BBPS score, compared to 94.0% assigned to the nurse counselling group. The 95% confidence interval of the relative risk difference (–0.8%) was –5.1% to 3.5%, which was within the prespecified non-inferiority margin of 10%. Thus, our findings showed that CBE is not inferior to nurse counselling in both the ITT and PP population (i.e., that the null hypothesis was rejected).