How contextual factors influence disparities in colorectal cancer screening

PURPOSE: This study addresses the chain of causation linking contextual factors to colorectal cancer (CRC) screening disparities by evaluating the effect of racism and socioeconomic inequalities as well as other environmental features on colorectal cancer screening participation. METHODS: We analyze data on adults 50 years of age and older without a prior CRC diagnosis from the 2005 California Health Interview Survey, a population-based telephone survey. Area-level data were obtained from administrative and publicly available survey data. We use multilevel models with fixed and random effects to estimate these contextual effects on individual-level CRC screening. PRELIMINARY RESULTS: Of the 21,500 study participants, approximately 55% were screened within 5 years with colonoscopy, sigmoidoscopy, or fecal occult blood test; 27% had never been screened for CRC. Higher proportions of Non-Hispanic whites (59%) and African-Americans (56%) were recently screened compared to other racial/ethnic groups (43%-50%). Those with insurance, higher education, higher income, and who reported no racial/ethnic discrimination within the health care system were more likely to have been recently screened. CONCLUSIONS: In addition to identifying individual characteristics associated with CRC screening in 5 racial/ethnic groups, we demonstrated the size and direction of contextual effects and explored how they contribute independently or synergistically to CRC screening. Multilevel modeling can attribute the unexplained variance to specific counties so that findings from this study will help state and local health planners identify priority areas and subgroups for program or policy interventions.