The role of sigmoidoscopy in colorectal cancer screening – public preferences and predicted uptake

Background Participation in cancer screening is crucial to maximise its benefit. In colorectal cancer (CRC) screening, stool tests or colonoscopies are commonly offered worldwide screening tests. In the German CRC screening programme, the insured can primarily choose between stool test and colonoscopy. However, sigmoidoscopy is also an evidence-based procedure to reduce CRC mortality and even prevent CRC. Based on individual preferences, we aim to estimate the uptake for either colonoscopy, sigmoidoscopy, or stool test in CRC screening. Methods In 2020, statutory insured individuals aged 50, 55, and 60 in Germany, Lower Saxony, were invited to participate in a discrete choice experiment (DCE). Each participant received 8 choice tasks, each of which presented two unlabelled (procedure A and B) screening alternatives defined by 6 attributes (CRC incidence and mortality, complications, preprocedural bowel preparation, need for transportation home, colonoscopy following a positive test result). Each attribute had 3 levels. To calculate the indirect utility and probability of uptake of stool testing, sigmoidoscopy, colonoscopy, and ‘no screening’, the preference weights of the attribute levels used to define the 4 alternatives were summed. Estimates were compared between standard screening (stool test or colonoscopy) and extended screening (+ sigmoidoscopy). External validity of the DCE was checked by comparing predicted and intended (2 items in the questionnaire) participation. Results From n = 666 valid respondents, a greater proportion of women (22.5%; 95%CI 16.2–28.9%) than men (13.4%; 95%CI 9.6–17.2%) preferred sigmoidoscopy in an extended screening scenario. Compared with standard screening, the predicted uptake for colonoscopy and the stool test as well as for ‘no screening’ was slightly lower when sigmoidoscopy was offered as an additional option. The extended screening could yield a slightly higher non-significant total participation in CRC screening in both women (+ 5.8%; 95%CI -0.4-12.0%) and men (+ 3.1; 95%CI -3.4-9.6%) than standard screening. Intended and preferred uptake did not differ substantially. Conclusions A relevant proportion of the eligible population, more women than men, appears to prefer sigmoidoscopy for CRC screening when given the option. This additional option tends to increase overall predicted participation in CRC screening. Future studies are needed to evaluate the acceptance and feasibility of the additionally offered sigmoidoscopy in today’s CRC screening. Trial registration DRKS00019010, 2019-11-18