ReviewComparing participation rates between immunochemical and guaiac faecal occult blood tests: A systematic review and meta-analysis
Introduction
Colorectal cancer (CRC) is the fourth most common cancer in the world, with 1.2 million people diagnosed with the disease in 2008 (Globocan, 2008). CRC screening reduces mortality from the disease (Pignone et al., 2002) and has been implemented in a number of countries across the world (Halloran, 2009).
FOBt screening has been shown to reduce CRC mortality rates by detecting the disease at an earlier stage (Hewitson et al., 2006). For many years the commonest form of FOBt was a guaiac based test (G-FOBt), whereby individuals apply small samples of bowel motion onto a test card with the aid of cardboard spatulas (Hewitson et al., 2006). The G-FOBt contains the chemical guaiac which in the presence of the haem component of blood in stool samples, and the application of hydrogen peroxide in the screening laboratory, results in an oxidation reaction which turns the G-FOBt blue (Burch et al., 2007). Immunochemical versions of the test (FIT) have been shown to be more specific and sensitive to detecting human blood than the guaiac predecessor (Halloran, 2009, Launoy et al., 2005). FITs detect intact haemoglobin using monoclonal or polyclonal antibodies raised against the globin component of blood (Burch et al., 2007).
Regardless of the merits of a particular test type, the reduction of CRC mortality depends heavily on the participation of individuals in CRC screening (Weller et al., 2009). A conjoint analysis study assessing patient preferences found that FIT was significantly preferred to the G-FOBt; the most important attribute of the test was what the test involved, followed by how accurate it was (Hawley et al., 2008). Barriers to CRC screening participation have been well documented over the years (Brouse et al., 2004). Research has shown that individuals are more reluctant to participate in CRC screening if they perceive the practicality of completing a FOBt as awkward (Schroy, 2002). For instance, if the test is considered embarrassing or distasteful, or individuals do not feel confident in carrying out the test successfully, participation will be lower. Similarly, the manipulation of faeces and storage of the completed test can prove problematic (O'Sullivan and Orbell, 2004). More recently, intentions to participate in CRC screening decreased when participants were given detailed information about how to collect faecal samples for a G-FOBt (von Wagner et al., 2011).
FIT has been heralded by some to be the more acceptable alternative to a G-FOBt, primarily because it does not require dietary restrictions and only one stool sample is necessary (Janda et al., 2002, Weller et al., 2009). These differences suggest that FIT is not only a better quality of test than G-FOBt but also more acceptable. However, there have been no systematic evaluations of this assumption. Therefore the aim of this study was to address this gap in the literature.
Section snippets
Objectives
The primary objective of this review was to compare participation rates of G-FOBt and FIT, where the newer FIT was compared with the standard G-FOBt. The secondary objective was to conduct an exploratory analysis to assess which characteristics of the test acted as barriers or facilitators to participation.
Inclusion criteria
Randomised control trials which assessed participation rates for G-FOBt versus FIT were included in this review. Studies were required to compare participation rates of two or more types of FOBt, measured by return rate of completed tests.
Exclusion criteria
Studies were excluded if participants completed more than one type of test as part of the study protocol, or if the FOBt was being compared with an invasive test i.e. flexible sigmoidoscopy or colonoscopy.
Information sources
Journal papers that met the inclusion criteria were
Results
In total, 354 titles and abstracts were screened for eligibility utilising the inclusion and exclusion criteria; see Fig. 1.
Seven studies met these criteria and were included in the meta-analysis (Cole et al., 2003, Federici et al., 2005, Hoffman et al., 2010, Hol et al., 2009, Hughes et al., 2005, Levi et al., 2011, van Rossum et al., 2008). Each study compared participation rates of G-FOBt with FIT for CRC screening. The characteristics of the included studies can be seen in Table 1.
The
Discussion
Overall, the participation rate was found to be significantly higher with FIT than with G-FOBt. Only Levi et al. (2011) reported a better compliance for G-FOBt dramatically increasing the heterogeneity among studies. As six out of the seven included studies drew similar conclusions, it was felt that the utility of a meta-analysis was justified because it increased the statistical precision of the point estimate. Therefore this review offered strong support for the hypothesis that the
Conclusion
Participation rates for FIT were significantly higher than G-FOBt, although the reasons for why this was the case were not conclusive. The outcome of this review is considered to be particularly relevant to programmes currently using the G-FOBt, where participation rates could benefit from the introduction of screening via FIT. However if FIT were to be used more widely, further investigation from a patient perspective is considered necessary.
Conflict of interest statement
The authors declare that there are no conflicts of interest.
Acknowledgments
With special thanks from GV to Professor Richard Shepherd (Academic Supervisor) and Professor Stephen Halloran (NHS Bowel Cancer Screening Programme — Southern Hub Director) for their support and help with this research. This research was funded via a studentship provided to GV by The Guildford Undetected Tumour Screening (G.U.T.S) charity, for part fulfilment of the degree PhD Health Psychology at the University of Surrey.
References (24)
Bowel cancer screening
Surgery
(2009)- et al.
Colorectal cancer screening adherence is higher with fecal immunochemical tests than guaiac-based fecal occult blood tests: a randomized, controlled trial
Prev. Med.
(2010) - et al.
Guaiac versus immunochemical tests: faecal occult blood test screening for colorectal cancer in a rural community
Aust. N. Z. J. Public Health
(2005) - et al.
Random comparison of guaiac and immunochemical fecal occult blood tests for colorectal cancer in a screening population
Gastroenterology
(2008) - et al.
Uptake in cancer screening programmes
Lancet
(2009) - et al.
Barriers to colorectal cancer screening in a low income urban population: a descriptive study
Health Educ.
(2004) - et al.
Diagnostic accuracy of faecal occult blood tests used in screening for colorectal cancer: a systematic review
J. Med. Screen.
(2007) - et al.
Participation in screening for colorectal cancer based on a faecal occult blood test is improved by endorsement by the primary care practitioner
J. Med. Screen.
(2002) - et al.
A randomised trial of the impact of new faecal haemoglobin test technologies on population participation in screening for colorectal cancer
J. Med. Screen.
(2003) - et al.
The immunochemical faecal occult blood test leads to higher compliance than the guaiac for colorectal cancer screening programmes: a cluster randomized controlled trial
J. Med. Screen.
(2005)