Population-Based Data Reveal Factors Associated with Organised and Non-Organised Colorectal Cancer Screening: An Important Step towards Improving Coverage

Abstract

We investigated factors associated with organised and non-organised colorectal cancer screening using faecal occult blood tests, based on data from 308 municipalities in Flanders (6.6 million residents, 57% of Belgium) during 2015–2017. Logistic regression with generalized estimating equations was used to assess the associations between municipal characteristics and organised and non-organised screening coverages. Factors associated negatively with both organised and non-organised screening: percentage of people aged 70–74 in the target population [OR (odds ratios) = 0.98, 95%CI (confidence interval): 0.97–0.99 and OR = 0.98, 95%CI: 0.96–0.999, respectively]; negatively with organised screening: average income [OR = 0.97, 95%CI: 0.96–0.98], percentage of people with a non-Belgian/Dutch nationality [OR = 0.962, 95%CI: 0.957–0.967]; positively with organised screening: percentages of men in the target population [OR = 1.13, 95%CI: 1.11–1.14], jobseekers [OR = 1.12, 95%CI: 1.09–1.15] and people with at least one general practitioner (GP) visit in the last year [OR = 1.04, 95%CI: 1.03–1.05]; positively with non-organised screening: number of patients per GP [OR = 1.021, 95%CI: 1.016–1.026], percentage of people with a global medical dossier handled by a preferred GP [OR = 1.025, 95%CI: 1.018–1.031]. This study helps to identify the hard-to-reach subpopulations in CRC screening, and highlights the important role of GPs in the process of promoting screening among non-participants and encouraging non-organised participants to switch to organised screening.

Differences and Similarities in Breast and Colorectal Cancer Screening Uptake Among Municipalities in Flanders, Belgium

“…Interestingly, a higher percentage of people with at least 1 general practitioner (GP) visit in last 12 months and people with children have been shown to be associated with lower uptake of both CRC and BC screening (more chances of being in Group 4 vs. Group 1). With regards to GP visits, these results are in contrast with those of a previous study that found that GP visits are positively associated with CRC screening coverage [17]. In this study, however, the association of GP visits and non-organized screening was more pronounced than the association with organized screening.…”

“…We found that percentages of people with non-Belgian/Dutch nationality and diabetes are associated with a lower probability of screening for CRC (more chances of being in Group 2 vs. Group 1) and BC (more chances of being in Group 3 vs. Group 1). With regards to foreign nationality, these findings are consistent with previous observations at both municipal and individual level [17], [24], [25] and can be explained by the reported perceived language barriers and embarrassment when talking about screening [26]. Moreover, migrants are a high-risk group for limited health literacy and may experience higher difficulties, compared to non-immigrant individuals, in processing health information and translating them it into healthy behaviors [27].…”

“…We found a marked association between average income and uptake of both BC and CRC screening (less chances of being in Group 2 vs. Group 1). It is interesting to compare our findings with results of previous studies which have found that, with regards to both BC and CRC screening, a higher average income is related to lower screening coverages for the organized screening, but to higher screening coverages for the non-organized (opportunistic) screening [17], [25]. Nevertheless, it should be kept in mind that, compared to this one, these studies investigated a different outcome (screening uptake vs. screening coverage).…”

“…With regards to the age groups considered, a higher percentage of people aged 65-69 was associated with lower CRC screening uptake (more chances of being in Group 2 vs. Group 1). Although, in this study, we could not assess the oldest age group participating in CRC screening (ages 70-74) because it is not included in the BC screening target population, previous studies have found a negative association with ages 70-74 and FOBT screening in Flanders [17] and other European countries [30]. It is plausible that people from the two age groups, both including elderly individuals, act in a similar manner: older people tend to suffer from multiple health issues that may need prioritization.…”

“…In order to minimize possible collider biases [16] a causal directed acyclic graph (DAG) based on prior knowledge about the Flemish organised screening programs [17], [18] was employed to identify covariates for adjustment when assessing the associations between municipal characteristics and profile of BC/CRC screening uptake. A multidisciplinary brainstorming session was organized between a medical doctor, two epidemiologists (amongst whom the program manager of the Flemish CRC screening program) and a sociologist to conceptualize the exposure -outcome relationship.…”