O-0020SOCIO-ECONOMIC AND GEOGRAPHICAL DISPARITIES IN COLORECTAL ADENOMAS AND COLORECTAL CANCERS DETECTION : A POPULATION-BASED STUDY

Background: Rural areas were previously shown to be associated with colorectal adenoma detection rates that were lower than in urban areas, with no significant difference for colorectal cancer (CRC) incidence. However, this analysis was relatively crude and did not include socio-economic data. The present study aimed at assessing the impact of socio-geographical disparities on colorectal adenoma detection and CRC incidence in the Department of Cote d’Or, France, before mass screening implementation. Methods: The Cote d’Or registry of digestive tumours has collected all cases of colorectal polyps and cancers diagnosed in a well-defined geographical area (Cote d’Or, France) since 1976. The study population included all patients > 20 years, residing in Cote d’Or with a known place of residence, diagnosed for the first time either with colorectal adenomas or incident CRC between 01/01/1995 and 12/31/2002. Socio-geographical variables included distance to primary care physician (PCP), distance to gastroenterologist (GE) and the European Deprivation Index (EDI) collected in the smallest French areas available. Heterogeneity and spatial autocorrelation were tested. Spatial Bayesian poisson regression models were used and compared using the Deviance Information Criteria (DIC). Results: On the whole, 5,399 patients were diagnosed with at least one adenoma and 2,125 with invasive incident CRC. Age- and gender-standardized adenoma detection rate (/100 000) was 151 [CI95% 147-156], with variations according to the EDI and the distance to PCP. Thus, age- and gender-standardized adenoma detection rate ranged from 164 [CI95% : 155-173] for the most affluent quintile to 144 [CI95% : 134-154] and 151 [CI95% : 141-161] for the two most deprived quintiles. Regarding distance to PCP, adenoma detection rates were 161 [CI95% : 155-167] in the lowest quintile (lowest distance to PCP), versus 117 [CI95%: 102-133] for the highest quintile (highest distance to PCP). On the contrary, no significant differences were observed according to distance to GE. Age-and gender-standardized CRC incidence rate was 48 [CI95% : 46-51] without any significant variation according to socio-economic deprivation or according to the distance to physicians. Age and gender adjusted Bayesian model identified geographical disparities in colorectal adenoma detection: overdetection around the regional capital city and underdetection on the periphery of the