How does a colorectal cancer screening decision aid plus patient navigation promote screening completion? A mediation analysis from randomized controlled trial data

Authors: Malo TL, Brenner AT, Weaver MA, Reuland DS

Category: Behavioral Science & Health Communication, Behavioral Science & Health Communication
Conference Year: 2018

Abstract Body:
Purpose: Screening is a powerful but underutilized colorectal cancer (CRC) prevention tool. CRC screening decision aids and patient navigation can improve screening completion. However, the mechanisms through which these interventions contribute to changes in screening behavior are not well understood. We sought to examine potential mediating effects of intermediate decision-making outcomes on CRC screening completion among patients who viewed a screening decision aid and received patient navigation. Methods: Participants (n=265) at two study sites were randomized to view either a CRC screening decision aid (intervention) or food safety (control) video before a primary care encounter. Immediately after the encounter, they completed a survey assessing intermediate decision-making outcomes, including CRC screening test preference (colonoscopy or fecal testing vs. none), knowledge (range: 0-6), discussion with their provider (yes/no), and self- efficacy to complete CRC screening (not at all [1] to extremely confident [5]). After completing the survey, intervention participants received support for screening completion from a patient navigator. Screening completion was assessed for all participants by electronic health record review six months after their encounter. We fit a probit path analysis model to assess the potential mediating roles of the intermediate decision-making outcomes on screening completion, controlling for study site. Results: CRC screening test preference was the only significant mediator of the relationship between the intervention and screening completion (p<0.001). This variable explained approximately 40% of the total effect of the intervention on screening completion. Model fit was good: root mean square error of approximation = 0 (90% confidence interval: 0, 0.074) and Tucker-Lewis Index = 1.039. Conclusion: Findings suggest that an intervention in which patients viewed a decision aid and received patient navigation increased CRC screening completion, in part, by enhancing patients’ ability to indicate a specific CRC screening test preference. Designing behavioral CRC screening interventions to facilitate patients’ test preference formation may improve their effectiveness. Future research should also consider measuring this construct.

Keywords: colorectal cancer; decision aids; path analysis; primary care; screening