In France, participation in organized colorectal cancer screening remains low. The objective of this study was to identify the determinants of participation in colorectal cancer screening in Isère, a French administrative entity.

This study examined the target population invited for screening between 2007 and 2008 in Isère. The statistical analysis method was based on a two-level logistic regression model: the first was the individual level relative to the individuals invited for screening and the second was an aggregate level corresponding to the socioeconomic level of an invited person’s residence area (IRIS: “Ilot regroupé pour l’Information Statistique”; Regrouped statistical information block). The evaluation of the socioeconomic level was based on the Townsend deprivation.

Participation varied depending on sex, age, and health insurance plan. The people residing in the least deprived IRISes participated more than individuals residing in the most deprived IRISes. The multilevel analysis showed a 24% difference in participation between the least and the most deprived IRISes.

The use of socioeconomic data on the IRIS geographical unit has identified, socially and geographically, the populations that participate the least, although this reflects “mean” behaviors. These results could be used to set up targeted actions to encourage participation in these populations.