Abstract
OBJECTIVE: To evaluate participation and participation patterns in a population-based screening programme for colorectal cancer (CRC) using the faecal immunochemical test (FIT). METHODS: All individuals invited to three consecutive screening rounds in the population-based CRC screening between October 2015 and December 2020 in the Stockholm-Gotland Region, Sweden were included. Patterns of participation were assessed. RESULTS: The study included 26 541 individuals which resulted in 79 623 screening events. The overall uptake rate was 71.5% and women had a significantly higher participation rate. The participation rate increased significantly between the first and third screening round for both men and women, and the increase was larger among men than women (66.1 to 70.7% vs. 73.1 to 75.4%). In total, 80.9% participated at least once. Consistent participation was the most common participation pattern (61.0%). The probability of attending all three consecutive rounds after initial participation was 87.7%. Over the three rounds, 17.4% participated after a reminder letter. Screening individuals attending after a reminder letter had a higher proportion of drop-outs in the following screening round compared to initial participants (15.4% vs 6.2%). CONCLUSION: A constant and high participation rate was observed in population-based FIT-screening for CRC. Initial participation was a strong predictor for continuous participation. The need for a reminder letter before participation was a risk factor for subsequent drop-out.