Providing Quantitative Information and a Nudge to Undergo Stool Testing in a Colorectal Cancer Screening Decision Aid: A Randomized Clinical Trial

Background. Guidelines recommend that patient decision aids should provide quantitative information about probabilities of potential outcomes, but the impact of this information is unknown. Behavioral economics suggests that patients confused by quantitative information could benefit from a nudge towards one option. We conducted a pilot randomized trial to estimate the effect sizes of presenting quantitative information and a nudge. Methods. Primary care patients (n = 213) eligible for colorectal cancer screening viewed basic screening information and were randomized to view (a) quantitative information (quantitative module), (b) a nudge towards stool testing with the fecal immunochemical test (FIT) (nudge module), (c) neither a nor b, or (d) both a and b. Outcome measures were perceived colorectal cancer risk, screening intent, preferred test, and decision conflict, measured before and after viewing the decision aid, and screening behavior at 6 months. Results. Patients viewing the quantitative module were more likely to be screened than those who did not (P = 0.012). Patients viewing the nudge module had a greater increase in perceived colorectal cancer risk than those who did not (P = 0.041). Those viewing the quantitative module had a smaller increase in perceived risk than those who did not (P = 0.046), and the effect was moderated by numeracy. Among patients with high numeracy who did not view the nudge module, those who viewed the quantitative module had a greater increase in intent to undergo FIT (P = 0.028) than did those who did not. Limitations. The limitations of this study were the limited sample size and single healthcare system. Conclusions. Adding quantitative information to a decision aid increased uptake of colorectal cancer screening, while adding a nudge to undergo FIT did not increase uptake. Further research on quantitative information in decision aids is warranted.