Socioeconomic position and participation in colorectal cancer screening

BACKGROUND: Colorectal cancer (CRC) screening with faecal occult blood test (FOBT) has the potential to reduce the incidence and mortality of CRC. Screening uptake is known to be inferior in people with low socioeconomic position (SEP) when compared with those with high position; however, the results of most previous studies have limited value because they are based on recall or area-based measures of socioeconomic position, and might thus be subject to selective participation and misclassification. In this study we investigated differences in CRC screening participation using register-based individual information on education, employment, and income to encompass different but related aspects of socioeconomic stratification. Also, the impact of ethnicity and cohabiting status was analysed. METHODS: A feasibility study on CRC screening was conducted in two Danish counties in 2005 and 2006. Screening consisted of a self-administered FOBT kit mailed to 177 114 inhabitants aged 50-74 years. Information on individual socioeconomic status was obtained from Statistics Denmark. RESULTS: A total of 85 374 (48%) of the invited returned the FOBT kits. Participation was significantly higher in women than in men (OR=1.58 (1.55-1.61)), when all socioeconomic and demographic variables were included in the statistical model. Participation also increased with increasing level of education, with OR=1.38 (1.33-1.43) in those with a higher education compared with short education. Also, participation increased with increasing income levels, with OR=1.94 (1.87-2.01) in the highest vs lowest quintile. Individuals with a disability pension, the unemployed and self-employed people were significantly less likely to participate (OR=0.77 (0.74-0.80), OR=0.83 (0.80-0.87), and OR=0.85 (0.81-0.89), respectively). Non-western immigrants were less likely to participate (OR=0.62 (0.59-0.66)) in a model controlling for age, sex, and county; however, this difference might be attributed to low SEP in these ethnic groups ((OR=0.93 (0.87-0.99), when adjusting for SEP indicators). CONCLUSION: This study based on individual information on several socioeconomic dimensions in a large, unselected population allowed for identification of several specific subgroups within the population with low CRC screening participation. Improved understanding is needed on the effect of targeted information and other strategies in order to reduce socioeconomic inequalities in screening.