Intervention Mediators in a Randomized Controlled Trial to Increase Colonoscopy Uptake Among Individuals at Increased Risk of Familial Colorectal Cancer

Background: Understanding the pathways by which interventions achieve behavioral change is important for optimizing intervention strategies. Purpose: We examined mediators of behavior change in a tailored-risk communication intervention that increased guideline-based colorectal cancer screening among individuals at increased familial risk. Methods: Participants at increased familial risk for colorectal cancer (N = 481) were randomized to one of two arms: (1) a remote, tailored-risk communication intervention (Tele-Cancer Risk Assessment and Evaluation (TeleCARE)) or (2) a mailed educational brochure intervention. Results: Structural equation modeling showed that participants in TeleCARE were more likely to get a colonoscopy. The effect was partially mediated through perceived threat (β = 0.12, p < 0.05), efficacy beliefs (β = 0.12, p < 0.05), emotions (β = 0.22, p < 0.001), and behavioral intentions (β = 0.24, p < 0.001). Model fit was very good: comparative fit index = 0.95, root-mean-square error of approximation = 0.05, and standardized root-mean-square residual = 0.08. Conclusion: Evaluating mediating variables between an intervention (TeleCARE) and a primary outcome (colonoscopy) contributes to our understanding of underlying mechanisms that lead to health behavior change, thus leading to better informed and designed future interventions. Trial Registration Number: ClinicalTrials.gov, NCT01274143.