Effectiveness of a decision aid for colorectal cancer screening on components of informed choice according to educational attainment: a randomised controlled trial

Background The decision to take up colorectal cancer screening has to be made on informed grounds balancing benefits and harms. Self-administered decision aids can support citizens in making an informed choice. A self-administered web-based decision aid targeting citizens with lower educational attainment has been evaluated within the target population. However, the effectiveness in the general screening population remains unexplored. The aim of this study was to evaluate the effectiveness of a web-based decision aid for colorectal cancer screening on components of informed choice among previous non-participants in colorectal cancer screening. Methods and findings The study was designed as a parallel randomised controlled trial among non-participants in colorectal cancer screening in Central Denmark Region (men and women aged 53–74 years). Respondents to baseline and follow-up questionnaires comprised the study population (n = 1,723). The intervention group received the decision aid electronically along with the second reminder. The control group received only the second reminder. The main outcomes (knowledge, attitudes, uptake and decisional conflict) were obtained through questionnaires data and from the Danish Colorectal Cancer Screening Database. The decision aid increased the uptake rate by 8 percentage points (95% CI: 3.4;12.6) but had no effect on either knowledge (scale score differences: 0.09; 95% CI: -0.05;0.24) or attitudes (0.45; 95% CI: -0.00;0.91). Decisional conflict decreased by 1.69 scale points (95% CI: -3.18;-0.20). The effect was similar across educational attainment levels. Conclusions The web-based decision aid offers a feasible way to provide individualised screening information in a "one size fits all" approach that may hold the potential to increase informed CRC screening uptake