Understanding Intention to Undergo Colonoscopy among Intermediate-Risk Siblings of Colorectal Cancer Patients: A Test of a Mediational Model

Background. There is a need for research to identify factors influencing intentions to undergo colorectal cancer (CRC) screening among family members at risk for CRC. This study tested a mediational model primarily guided by Ronisʹ elaboration of the Health Belief Model in predicting intention to have colorectal cancer screening among siblings of individuals diagnosed with colorectal cancer prior to age 56 years. Methods. Data were collected from 534 siblings of individuals diagnosed with CRC. A baseline survey was administered by telephone. Measures included perceived susceptibility, CRC severity, physician and family support for CRC screening, cancer-specific distress, the closeness of the relationship with the affected sibling, and future intention to have a colonoscopy. Participant age, gender, and number of prior colonoscopies, as well as the stage of the affected patientʹs cancer and time from the patientʹs diagnosis to the interview, were controlled for in the analyses. Results. The proposed model was not a good fit to the data. A respecified model was fit to the data. In this model, physician support, family support, and sibling closeness were significantly associated with both perceived benefits and barriers. Perceived severity was associated with barriers. Benefits and barriers, as well as cancer-specific distress, were directly associated with colonoscopy intentions. Results were consistent with a mediational role for benefits and barriers in the associations of sibling closeness and with a mediational role for barriers in the association between perceived severity and colonoscopy intentions. Family and physician support impacted intentions both directly and indirectly through effects on benefits and barriers. Perceived risk was not associated with benefits, barriers, or colonoscopy intentions. Conclusion. Intervention efforts to increase colonoscopy intentions may benefit from targeting family influences, particularly the affected proband in the family, as well as physician influence, cancer-related distress, perceived CRC severity, and perceived benefits and barriers to colonoscopy.