To participate or not : decision-making and experiences of individuals invited to screening for colorectal cancer

Background: Colorectal cancer (CRC), the third most common and second most fatal cancer worldwide, can to a large extent be prevented by organised population-based screening. In Sweden, organised CRC screening only operates regionally, yet it is soon to be implemented at the national level with the intention of reducing overall mortality of the disease. CRC screening programme effectiveness is, however, often limited by low rates of participation. Understanding reasons for non-participation is thus crucial, and especially when designing and introducing new screening programmes. Simultaneously, individuals should be able to make informed and value-congruent decisions as to whether or not to participate, and ideally make these decisions through shared decision-making. Aim: The overall aim of this thesis is to enhance the understanding of factors and experiences associated with participation and non-participation in screening for colorectal cancer. Methods: To address this aim, both quantitative and qualitative approaches were used. Study participants were recruited from the Screening of Swedish Colons (SCREESCO) trial, in which individuals aged 59–62 had been randomised and invited to participate in either screening by colonoscopy or by faecal immunochemical test (FIT). For Studies I–III, either part or all of the data were collected using an online survey consisting of four questionnaires: two on health literacy (HL; the Swedish Functional Health Literacy Scale and the Swedish Communicative and Critical Health Literacy Scale; Study I); one on anxiety (the State–Trait Anxiety Inventory scale; Study II); one on knowledge, values and preferences, and involvement (the SCREESCO questionnaire; Study III), for which the responses and scores of screening participants (n = 1,256–1,320) and screening non-participants (n = 153–161) were analysed and compared using descriptive and inferential statistics. Moreover, qualitative data for Studies I and IV, exploring views about being invited to CRC screening and experiences of the screening procedure, were collected through six focus group discussions (screening participants, n = 24) and 34 individual telephone interviews (screening participants, n = 20; screening non-participants, n = 14), and analysed using inductive qualitative content analysis. Results: The findings of this thesis showed no differences in HL levels between screening participants and non-participants, with the majority of both groups having adequate HL (Study I) and equally expressing pros and cons of the screening information materials (Studies I, IV). Screening participants and non-participants likewise displayed a similar pattern for CRC- and screening related knowledge, which varied across items; e.g., 90% recognised blood in the stool as a CRC symptom, but less than 50% mentioned overweight, smoking, alcohol, and physical inactivity as CRC risk factors (Study III). Screening non- participants were less sure about their CRC risk and the ability of screening to reduce the risk of dying from CRC (Study III). In many respects, values and preferences of the groups differed; i.e., while screening participants mostly considered the importance of early detection and CRC worry when choosing to participate in screening, non-participants took the risk of procedural discomfort and complications under most consideration when choosing to decline (Study III). Psychological impact of screening was generally low; i.e., most screening participants and non-participants scored low for anxiety related to the decision and there was no difference in anxiety levels between the groups (Study II). Likewise, screening participants were often unconcerned about going through the screening procedure (Study IV). Still, some individual characteristics and timepoints of the screening process were associated with experiencing greater anxiety or concerns (Studies II, IV). In both groups, healthcare professionals were generally not involved in decisional discussions or consulted for information about screening (Study III). In established contacts, however, their role was considered important (Studies III, IV). Undergoing screening by FIT was most often depicted as simple and easy, apart from a few practicalities (Study IV). Colonoscopy screening was associated with arduous preparations and pain and also with no discomfort at all (Study IV). Both screening procedures were described as interfering with individuals’ daily lives, with colonoscopy screening appearing more cumbersome for those who had limited ability to control their working hours (Study IV). Conclusions: In this thesis, most individuals, irrespective of whether they were screening participants or non-participants, had adequate HL, felt well-informed but partially lacked knowledge of CRC and screening, did not involve any healthcare professional in their decision-making, and experienced low levels of anxiety related to their decision. Both groups described pros and cons of the screening information materials but differed in respect to their values and preferences by taking various matters into consideration when deciding whether to undergo screening. Screening participants experienced various emotions and logistical concerns, with the most important being the influence of individuals’ work- and life situation for colonoscopy experience. These findings indicate that there is room for improvement in the current communication and arrangement of CRC screening for facilitating high, informed, and equal participation. Furthermore, the results suggest that individuals have various needs and may require different means of support throughout the screening process