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 Antonio Federici MD, MPH a , Chiara Marinacci BSc b , Marialuisa Mangia MD c , Piero Borgia MD a , Paolo Giorgi Rossi PhD a, * , Gabriella Guasticchi MD a a Agency for Public Health, Lazio Region, Via di S. Costanza 53, 00198 Rome, Italy b Epidemiology unit Piedmont Region, Via Sabaudia 164, 10095 Grugliasco (Turin), Italy c Local Health Unit ASL RM B, Via Filippo Meda 35, 00100 Rome, Italy Accepted 20 March 2006 Abstract 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. # 2006 International Society for Preventive Oncology. Published by Elsevier Ltd. All rights reserved. Keywords: Colorectal cancer screening; Faecal occult blood test; Flexible sigmoidoscopy; Compliance; Cluster-randomized trial; Detection rate; Referral rate; Socio-economic level; Relative risks; Provider-related factors; Colonoscopy; Guaiac test 1. Introduction Observational studies of subjects who have undergone flexible rectosigmoidoscopy (FS) [2,3], and randomized trials using faecal occult blood tests (FOBT) [4–8] have provided evidence of the efficacy of screening programs. Many scientific societies and government agencies reco- mmend screening for colon cancer for the at-risk popu- lation, often specifying either FOBT, FS or colonoscopy, although following a variety of timetables [1–3,9–18]. The reported range of participation to screening programs is extremely wide, and it is very hard to pinpoint the reasons for this variability: in subjects at risk because of age, reported participation levels vary, with FOBT ranging from 12 to 95% in community-based programs and from 12% to 27% [18–21] when FS was offered on its own; in the ongoing UK Flexible Sigmoidoscopy Screening Trial, reported compliance is 71.3% [22]. This considerable variability is all the more problematic because estimated levels of participation not only determine cost benefits, but www.elsevier.com/locate/cdp Cancer Detection and Prevention 30 (2006) 347–353 Abbreviations: CRC, colorectal cancer; CONSORT, consolidated stan- dards of reporting trials; FOBT, faecal occult blood test; FS, flexible rectosigmoidoscopy; GP, General Practitioner; LHU, Local Health Units; OR, odds ratios; RR, relative risk * Corresponding author. Tel.: +39 0683060438; fax: +39 0683060463. E-mail address: giorgirossi@asplazio.it (P. Giorgi Rossi). 0361-090X/$30.00 # 2006 International Society for Preventive Oncology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.cdp.2006.03.009