Workload implications of modifying the BCSP algorithm for referral to colonoscopy
The NHS Bowel Cancer Screening Programme (BCSP) provides biennial screening to men and women aged 60-74 years. The guaiac-based faecal occult blood test has six sample windows (two samples from three stools), any of which may test positive for blood. If five or six of the windows (or 'spots') are positive, the subject is referred to a specialist screening practitioner (SSP) to discuss colonoscopy (the majority of referrals result in colonoscopy). If between one and four spots are positive the subject is asked to complete up to two further tests to reach a definitive test result. It is possible that subjects with between one and four positive spots on kit 1 may be underserved by the current algorithm due to intermittent bleeding from colonic neoplasia and the risk of drop out.
Spot positivity was reviewed for subjects invited for screening by the BCSP Southern Hub in 2012-2013. Overall test positivity was calculated as the proportion of subjects with a definitive test result that had an abnormal result and were referred for colonoscopy.
There were 13,731 SSP referrals in 2012 and 12,161 in 2013. Referral with three or four positive spots on kit 1 would have increased positivity by 0.24 percentage points, generating an additional 1,606 (11.70%) referrals in 2012, and a further 1,602 (13.17%) referrals in 2013. Referral with four positive spots would have increased positivity by 0.1 percentage points, generating an extra 687 (5.00%) referrals in 2012 and 660 (5.43%) in 2013.
During 2012/2013, a change to the algorithm for referral would have increased referrals by about 5% (four spots positive) or 12% (three or four positive spots) and an average increase in the SSP workload of about 40 or 95 appointments per screening centre per year, with a similar increase in the colonoscopy workload.
We would like to gratefully acknowledge Theo Giannopoulos and Susanne Booth at Castle Hill Hospital for their help in acquiring ovarian tissue samples, and Jane Smales for coordinating the clinical aspects of the study. This study is funded by a grant from NC3Rs (Registry File: G1100600).
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