Abstract
BACKGROUND: Many countries have established organized colorectal cancer screening programs because they can reduce mortality and incidence from the disease; however, they rely on high participation rates, which are often suboptimal. This study examined the effectiveness of two reminder interventions on uptake rates in Ireland's population-based BowelScreen program. METHODS: Employing a quasi-experimental design, one intervention mailed the fecal-immunochemical test (FIT) directly to clients not responding to an initial invitation; the other mailed a reminder letter modified with behavioral insights. Interventions were tested separately and in combination and compared to the standard reminder letter (1: standard reminder letter [SRL]; 2: modified reminder letter [MRL]; 3: SRL + FIT direct [FITD]; and 4: MRL + FITD). PRIMARY OUTCOME: overall uptake rate (test completion at 5 months); Subgroup outcome: uptake rate among only those receiving reminders. Outcomes were modeled using multivariable logistic regression with group allocation as a fixed effect, adjusted for sex and deprivation. RESULTS: Uptake was significantly higher in the FITD groups (SRL: 48%; MRL: 50%; SRL + FITD: 54%; MRL + FITD: 54%; p < .001). After adjustment, compared to the SRL group, FITD groups had significantly higher odds of uptake (MRL: odds ratio [OR], 1.09; 95% confidence interval [CI], 0.96-1.23; SRL + FITD: OR, 1.30; 95% CI, 1.14-1.48; MRL + FITD: OR, 1.26; 95% CI, 1.11-1.44). This was also the case for subgroup analysis. The MRL did not result in higher uptake compared to SRL. CONCLUSION: Mailing the FIT kit directly to nonresponders resulted in improved FIT uptake. Organized FIT-based screening programs not reaching uptake targets should consider implementing this strategy if not already in place.