S689 Beyond the Envelope: Harnessing Social Science to Boost Colorectal Cancer Screening Rates in Mailed FIT Outreach

Introduction: Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths in the US. It is highly preventable through regular screening, but screening remains inconsistent. Mailed stool-based fecal immunochemical testing (FIT) improves screening rates, however prior studies suggest return rates of only 20-30%. This study aims to determine whether enhancing communications with evidence-based social psychology content in mailed FIT kits improves screening rates. Methods: This single-center randomized controlled trial focused primarily on Medicare patients at average-risk for colon cancer who were not up-to-date on CRC screening, based on EHR query. Patients were randomly assigned to one of 2 interventions: original communication (a series of standard communications, including a pre-mailing letter, FIT test letter, and reminders via text or robo-call); or enhanced communication (the same sequence, but incorporating social psychology and behavioral economics principles like personalization and anticipated regret to encourage FIT completion). We compared the rate of FIT test return at 90 days. Results: A total of 4,122 patients were included with a median age of 69 years. Baseline characteristics were similar across both groups. Within 90 days, 27% of all patients successfully completed the FIT test: 29% of patients receiving the enhanced communication had FIT test returned within 90 days compared to 26% of patients who received the original communication. The unadjusted odds ratio for obtaining patients’ FIT tests within 90 days was 1.14 (95% CI 0.99-1.31) for the enhanced communication outreach compared to the original communication (P = 0.065). Conclusion: The FIT test return rate in the enhanced communication group was not significantly higher than that of the original communication group. However, the overall return rate compares favorably to previous studies. Using evidence-based social psychology principles in mailed FIT communications did not appreciably improve CRC screening, but mailed FIT remains a key tool for reaching unscreened individuals. Future analysis will assess FIT return patterns across subgroups.