Is the type of test used for mass colorectal cancer screening a determinant of compliance? A cluster-randomized controlled trial comparing fecal occult blood testing with flexible sigmoidoscopy

Background: The efficacy of colorectal cancer screening has been proved, and three different screening tests are recommended by international guidelines: the faecal occult blood test, flexible sigmoidoscopy and colonoscopy. While the effectiveness of a screening program depends on the compliance obtained, the role of the type of test on compliance has not yet been sufficiently studied. Aims: To measure the effect of the type of screening test used, i.e. faecal occult blood test or flexible sigmoidoscopy, on the compliance to colorectal cancer screening programs. Subjects and methods: A cluster-randomized two-arm trial was conducted. We randomly assigned 20 GP's practices that had an average of 150 patients between 50 and 74 years old. Results: 1449 individuals were referred to faecal occult blood test and 1538 to flexible sigmoidoscopy. The faecal occult blood test obtained higher compliance: 17.2% (95%CI 12.5-25.7) versus 7.0% (95%CI 5.7-9.0). The socio-economic status was an effect modifier of the test type: the effect of the type of test was smaller in low socioeconomic classes. Conclusions: The type of screening test used for colorectal cancer is a determinant of participation. In a low compliance area, better compliance will result from offering the faecal occult blood test than from the flexible sigmoidoscopy. (c) 2006 International Society for Preventive Oncology. Published by Elsevier Ltd. All rights reserved.