General practitioner endorsement of mail-out colorectal cancer screening: The perspective of nonparticipants.

Despite the health and economic benefits associated with mail-out colorectal cancer (CRC) screening, participation in programs across the world is suboptimal. A letter from the recipient's general practitioner (GP) endorsing program participation has been shown to have a consistent, but modest, effect on screening uptake; however, the mechanisms by which GP endorsement is effective have not been investigated. The purpose of the present study was to evaluate the potential utility of GP endorsement letters or SMS in the context of facilitating bowel cancer screening in previous nonparticipants and to identify mechanisms underlying responses. A cross-section of nonparticipants in the Australian National Bowel Cancer Screening Program (N = 110) was randomly assigned to view a letter or SMS from a GP endorsing participation via an online survey. Ordinal responses reflecting effectiveness of, and influences on, GP endorsement were collected along with open questions regarding other potential endorsers. Percentages, means, and 95% confidence intervals were calculated and compared. Fifty-two percent of the sample agreed that GP endorsement would encourage their future participation. Responses did not differ between SMS and letter formats. Trust in the GP had significantly more influence on response to GP endorsement than the credibility or medical knowledge. Other health professionals and cancer survivors were commonly suggested as alternative sources of endorsement. Interventions to improve CRC screening participation could benefit from the routine implementation of GP endorsement from GPs, other trusted health professionals, or cancer survivors, particularly by encouraging people who forget or procrastinate over collecting a stool sample.