Sociodemographic predictors of participation in colorectal cancer screening.

Purpose: Colorectal cancer screening by inviting citizens to complete a test for blood in faeces was initiated in Denmark in 2014. We have examined sociodemographic predictors that influence participation to identify factors that could be targeted to increase compliance. Methods: National registers were used to link data on invitations for colorectal cancer screening in Denmark from 2014 to 2015. Region of residence, age, gender, immigration status, income, educational level and marital status were identified. Logistic regression analysis was used to estimate the risk of non-participation for invited citizens while adjusting for all other sociodemographic variables. Results: A total of 854,237 individuals were included in the analysis. The national participation proportion was 65.33%, with significant differences between sociodemographic groups. Participation proportions were the lowest in non-Western immigrants (53.00%), individuals without a partner (54.05%) and those in the lowest income quartile (54.65%), with subgroup participation as low as 40.56%. The highest participation proportion was seen in individuals in the highest income quartile (71.56%). Region of residence, age, gender, educational level, income quartile, marital status and immigration status all had statistically significant independent differences in risk of non-participation after full model adjustment. Conclusion: Participation in colorectal cancer screening was high in Denmark in 2014 and 2015. Large differences in participation were seen between sociodemographic subgroups, potentially resulting in social inequality in the benefits from screening. Future efforts to increase participation should focus on the low compliance subgroups, such as singles, non-Western immigrants and people from the lowest socioeconomic groups.