Elsevier

Preventive Medicine

Volume 55, Issue 2, August 2012, Pages 87-92
Preventive Medicine

Review
Comparing participation rates between immunochemical and guaiac faecal occult blood tests: A systematic review and meta-analysis

https://doi.org/10.1016/j.ypmed.2012.05.006Get rights and content

Abstract

Background

Biennial screening with faecal occult blood tests (FOBts) has been found to reduce colorectal cancer mortality. Faecal immunochemical tests (FITs) are superior to guaiac faecal occult blood tests (G-FOBts) due to their improved sensitivity and specificity. However the effectiveness of a screening programme depends highly on participation rates. The aim of this study was to review studies comparing guaiac faecal occult blood tests and faecal immunochemical tests, in terms of participation rates.

Methods

We searched PubMed and the Cochrane Library (2000–September 2011) to identify randomised control trials comparing guaiac faecal occult blood test with faecal immunochemical test participation rates. One author screened the titles and abstracts, and performed data extraction which was then checked by the other authors. Risk of bias in the included studies was also assessed.

Results

Seven studies met the eligibility criteria and were entered into a meta-analysis. Participation rates were significantly higher for individuals offered faecal immunochemical tests compared to those offered a guaiac faecal occult blood test (RR 1.21; 95% CI 1.09–1.33). Potential factors that could have influenced participation were discussed.

Conclusions

Colorectal cancer screening programmes currently using guaiac faecal occult blood tests could improve participation rates by converting to faecal immunochemical tests. More research examining the acceptability of faecal immunochemical tests, from a patient perspective, is warranted.

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.

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