Background
Colorectal cancer (CRC) is the third most diagnosed cancer and the second most common cause of cancer death worldwide [
1,
2]. Screening of CRC is highly effective at reducing the incidence and mortality of CRC, through the early detection of pre-cancerous polyps or CRC cases as well as facilitating early management and treatment [
1,
3‐
5]. If detected early, more than 90% of cases can be successfully treated and the significant risk of CRC-associated mortality can be reduced, with patients surviving at least five years [
1,
3,
4]. Subsequently, the total healthcare cost for managing CRC can be decreased significantly [
5].
Endoscopy-based (colonoscopy or sigmoidoscopy) and stool-based (Fecal Occult Blood Test (FOBT): Fecal Immunochemical Test (FIT) or Guaiac Fecal Occult Blood Test (gFOBT)) tests are the most used effective screening modalities for the early detection of CRC [
1,
6]. Program guideline recommendations for CRC screening, including target age groups and the choice of screening modalities, vary by country [
1]. The FIT kits have been recommended for population-based programs [
1]. High completion to FIT screening is essential for achieving benefits; however, screening rates remain suboptimal even in the high-income countries with established cancer screening programs [
7,
8].
Health system access factors including not having a regular healthcare provider (i.e., with whom the patient develops a long-term relationship for assessment of physical and mental health issues) and fewer visits with general practitioner (GPs) are associated with lower rates of CRC screening [
8‐
10]. Socially disadvantaged groups benefit less from screening programs because of their multiple, cumulative intersecting vulnerabilities that may lead to limited access to the healthcare system [
9]. Uptake varies considerably by sociodemographic factors including ethnicity, educational attainment, language spoken, area of residence, income, and marital status [
11‐
15]. For instance, rural residents are less likely to have regular screening as they are less likely to have a regular GP [
15,
16], make fewer visits to GPs [
17], and need to travel further to seek care [
18].
Systematic reviews [
19‐
21] indicate that multicomponent interventions are most effective in increasing CRC screening uptake among patients, and this is corroborated by the Community Preventive Service Task Force– a non-federal panel of experts created by the United States Department of Health and Human Services to guide population health strategies [
22‐
24]. The multicomponent intervention approach combines two or more patient-centered interventions targeted at multiple levels (patients, providers and organizational or healthcare systems) to increase community demand and access, while providing screening services to promote CRC screening uptake among patients [
23,
24]. Interventions that include patient reminders, patient education, and improved FIT kit access help address factors contributing to low CRC screening rates [
22‐
24].
However, the effectiveness of multicomponent interventions that are targeted to address the lower CRC screening participation rates of disadvantaged populations with limited access to the healthcare system has not been reviewed or synthesized. The synthesized effectiveness evidence is critical for guiding the future design and implementation of population-wide FIT programs tailored to these disadvantaged groups. This rapid review aimed to systematically review and synthesize evidence on the effectiveness of FIT programs to increase CRC screening in populations who do not have a regular healthcare provider or are considered disadvantaged regarding healthcare system access (e.g., immigrants, low-income populations).
Discussion
This review synthesized evidence on the effectiveness of FIT programs in increasing CRC screening among disadvantaged groups with no regular healthcare provider or limited healthcare system access. We summarized findings across three intervention design-related themes: Delivery of Culturally-tailored Programs; Method of Delivery for FIT: Mail-out and In-person; and Follow-up Reminders. Findings could inform (re)design and implementation of large-scale interventions to improve FIT uptake among this target population.
Overall, culturally-tailored programs involving communication strategies (e.g., specific messages crafted with plain language and translated into different languages; participation of lay health educators; motivational messages) may increase the effectiveness of FIT programs. This is consistent with other research describing language and literacy as structural barriers compromising patient navigation, and thus access to health services [
23].
While it remains unclear if mail-out or in-person FIT delivery was more effective, we found that the use of additional strategies along with each mode of delivery may increase FIT kit return rates. For example, a motivational screening letter, a cost-free FIT kit, and live phone interaction should be implemented in mail-out programs. For in-person delivery, demonstration of how to collect FIT sample and home visits may better meet the needs of the populations with limited healthcare access. Despite only one study combining FIT program with other cancer screening programs, its success in CRC screening echoes recommendations elsewhere of integration of preventative cancer procedures for opportunistic screening [
55]. However, opportunistic screening should not replace organized FIT screening programs to ensure universal invitation and equitable participation of all eligible patients.
As part of a strategy to increase community demand for CRC screening, reminders have successfully alerted patients and increased screening rates [
56,
57]. Reminders were mainly effective in increasing rates of request and receipt of FIT kits, but not necessarily return rates. Our findings showed that reminders may be less effective in increasing the level of FIT among population groups with prior FIT completion screening. This may signal a good retention rate in the FIT program. It is also important to consider that live reminders may be cost-prohibitive as they require intensive interactions with patients. While automatic notification may be an alternative, it may fail to address patients’ fears and concerns [
57].
Uptake of follow-up colonoscopy among participants with abnormal FIT results varied across studies (from 14.8% [
47] to 93.3% [
31])– this variability was reported elsewhere [
57]. As improving FIT screening rates may not ensure care continuity, adequate infrastructure [
57] becomes critical to ensure patients are aware of the benefits of undergoing subsequent colonoscopy and have easy access to follow-up care.
This population group with no regular healthcare provider or limited access to the healthcare system experiences multiple, intersecting disadvantages that perpetuate and increase barriers to healthcare system access. Recognizing that, we used a specific tool [
27] to distill the social determinants of health affecting FIT uptake. Our review uncovered social factors that may reduce people’s participation of FIT screening programs, which aligns with the literature [
58,
59]. Findings suggest decision-makers and healthcare practitioners should consider the needs and priorities of specific social groups (e.g., religious groups) when designing intervention strategies. Intentional targeting and tailoring of the interventions to the populations’ identities and local contexts are needed for equitable participation in universal FIT programs.
Our review has some limitations. Our population criterion specified the inclusion of studies targeting populations without regular healthcare providers or describing their populations as medically-underserved or experiencing disadvantages regarding healthcare access. We had to rely on the information provided by those studies, which was often vague or unclear. As such, the study team met regularly to discuss the inclusions. However, there is still uncertainty about the population’s lack of or limited access to regular healthcare providers or to the healthcare system. In some studies, authors identified populations as medically-underserved; however, recruitment occurred in healthcare settings (e.g., health clinics) [
33,
38,
40,
42,
43,
45,
46,
49] or employed community-based strategies [
30,
31,
36,
40,
44,
47,
48,
51‐
54]. Similarly, in other studies it was unclear whether or not
having an assigned family doctor meant having a regular healthcare provider (see, for instance, Gomes et al. 2021 [
37]). A limitation in the included studies was the different meanings for the term ‘uptake’ as defined by study authors. For example, uptake could refer to the collection/receiving FIT kit or the kit return or completion of FIT (see, for instance, Clarke et al. 2016 [
33] and Bartholomew 2019 [
30], respectively). To avoid misinterpretation, we recorded terms as presented by the original authors. Due to the heterogeneity of the study design and definition of the main outcomes, we were unable to perform a meta-analysis. The included studies had important methodologic limitations that preclude conclusions concerning effectiveness (only eight papers were scored as of moderate quality, and one, as strong). Lastly, given that most of the findings came from studies using randomized control trial and controlled clinical trial designs, we acknowledge evaluating implementation and effectiveness outcomes in real world settings were out-of-scope. Their findings do not discuss the policy and administrative-practice implications for planning and implementation of real-world public health interventions, such as local population’s needs, costs and resource requirements, scalability and sustainability of the programs, and organizational factors associated with the health system context.
The strengths of this rapid review include: a comprehensive search strategy to account for the nuance of the language around healthcare system access; quality appraisal; use of rigorous and systematic methods for screening and assessment; and a detailed analysis on social determinants of health affecting the effectiveness of FIT programs.
Overall, our findings contribute to the literature in which most reviews on FIT programs have thus far focused on either general population [
19,
21,
57,
60] or specific socially disadvantaged groups, like rural populations and low-income populations [
20,
61]. To the best of our knowledge, this is the first review on the topic investigating this specific population group. Another unique aspect of this review is the multidimensional analysis of the FIT programs. We examined closely the multiplicity of factors– from features of the programs to the social background and identities of the patients– and their interconnections that may influence the success in achieving the health goals set by the CRC screening initiatives. Enriched with the use of PROGRESS-Plus framework [
27], our review gathered the evidence that may be an indicative of what has worked, for whom, and under what circumstances. This is a critical knowledge in informing (re)design and implementation of population-wide, equity-informed programs in real-world settings.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.