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Optimising faecal occult blood screening:retrospective analysis of NHS Bowel Cancer Screening data to improve the screening algorithm.

ABSTRACT: Colorectal neoplasia causes bleeding, enabling detection using Faecal Occult Blood tests (FOBt). The National Health Service (NHS) Bowel Cancer Screening Programme (BCSP) guaiac-based FOBt (gFOBt) kits contain six sample windows (or 'spots') and each kit returns either a positive, unclear or negative result. Test kits with five or six positive windows are termed 'abnormal' and the subject is referred for further investigation, usually colonoscopy. If 1-4 windows are positive, the result is initially 'unclear' and up to two further kits are submitted, further positivity leads to colonoscopy ('weak positive'). If no further blood is detected, the test is deemed 'normal' and subjects are tested again in 2 years' time. We studied the association between spot positivity % (SP%) and neoplasia.Subjects in the Southern Hub completing the first of two consecutive episodes between April 2009 and March 2011 were studied. Each episode included up to three kits and a maximum of 18 windows (spots). For each positivity combination, the percentage of positive spots out of the total number of spots completed by an individual in a single-screening episode was derived and named 'SP%'. Fifty-five combinations of SP can occur if the position of positive/negative spots on the same test card is ignored.The proportion of individuals for whom neoplasia was identified in Episode 2 was derived for each of the 55 spot combinations. In addition, the Episode 1 spot pattern was analysed for subjects with cancer detected in Episode 2.During Episode 2, 284,261 subjects completed gFOBT screening and colonoscopies were performed on 3891 (1.4%) subjects. At colonoscopy, cancer was detected in 7.4% (n=286) and a further 39.8% (n=1550) had adenomas. Cancer was detected in 21.3% of subjects with an abnormal first kit (five or six positive spots) and in 5.9% of those with a weak positive test result.The proportion of cancers detected was positively correlated with SP%, with an R(2) correlation (linear) of 0.89. As the SP% increased from 11 to 100%, so the colorectal cancer (CRC) detection rate increased from 4 to 25%. At the lower SP%s, from 11to 25%, the CRC risk was relatively static at ~4%. Above an SP% of 25%, every 10-percentage points increase in the SP%, was associated with an increase in cancer detection of 2.5%.This study demonstrated a strong correlation between SP% and cancer detection within the NHS BCSP. At the population level, subjects' cancer risk ranged from 4 to 25% and correlated with the gFOBt spot pattern.Some subjects with an SP% of 11% proceed to colonoscopy, whereas others with an SP% of 22% do not. Colonoscopy on patients with four positive spots in kit 1 (SP% 22%) would, we estimate, detect cancer in ~4% of cases and increase overall colonoscopy volume by 6%. This study also demonstrated how screening programme data could be used to guide its ongoing implementation and inform other programmes.

SUBMITTER: Geraghty J

PROVIDER: S-EPMC4260024 | biostudies-other | 2014 Nov

REPOSITORIES: biostudies-other

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Project description:ObjectivesThrough the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP), men and women in England aged between 60 and 74 years are invited for colorectal cancer (CRC) screening every 2 years using the guaiac faecal occult blood test (gFOBT). The aim of this analysis was to estimate the cost-utility of the faecal immunochemical test for haemoglobin (FIT) compared with gFOBT for a cohort beginning screening aged 60 years at a range of FIT positivity thresholds.DesignWe constructed a cohort-based Markov state transition model of CRC disease progression and screening. Screening uptake, detection, adverse event, mortality and cost data were taken from BCSP data and national sources, including a recent large pilot study of FIT screening in the BCSP.ResultsOur results suggest that FIT is cost-effective compared with gFOBT at all thresholds, resulting in cost savings and quality-adjusted life years (QALYs) gained over a lifetime time horizon. FIT was cost-saving (p<0.001) and resulted in QALY gains of 0.014 (95% CI 0.012 to 0.017) at the base case threshold of 180 µg Hb/g faeces. Greater health gains and cost savings were achieved as the FIT threshold was decreased due to savings in cancer management costs. However, at lower thresholds, FIT was also associated with more colonoscopies (increasing from 32 additional colonoscopies per 1000 people invited for screening for FIT 180 µg Hb/g faeces to 421 additional colonoscopies per 1000 people invited for screening for FIT 20 µg Hb/g faeces over a 40-year time horizon). Parameter uncertainty had limited impact on the conclusions.ConclusionsThis is the first published economic analysis of FIT screening in England using data directly comparing FIT with gFOBT in the NHS BSCP. These results for a cohort starting screening aged 60 years suggest that FIT is highly cost-effective at all thresholds considered. Further modelling is needed to estimate economic outcomes for screening across all age cohorts simultaneously.

Project description:Interventions: Name of intervention: gender specific mail-administered screening invitation strategies. All participants will receive an offer to participate in a free FOBT which will be delivered by mail. Intervention arms will differ from control according to the information included in the materials accompanying the screening offer. All study participants will receive a standard screening reminder irrespective of their intervention group. Intervention materials will target specific psychosocial variables previously identified as being related to male participation in FOBT screening. The intervention period is 14 weeks. All participants will receive a screening offer according to the following timeline. Baseline: Advance notification letter sent Week two: Invitation package sent Week eight: Reminder letters sent to those who have not completed an FOBT Week 14: Data collection ceases. Arm 1: Control The control arm will receive a standard offer to participate in FOBT screening designed to mimic the strategy utilised by the Australian national bowel cancer screening program (NBCSP). The standard offer includes an advance notification letter and a screening invitation package. The advance notification letter is sent two weeks prior to the screening invitation package and is designed to alert participants that an invitation to screen for CRC with an FOBT will soon follow. The standard advance notification letter introduces basic information about colorectal cancer and the health benefits of screening. The screening invitation package includes a) a screening invitation letter b) an immunochemical FOBT with associated instructions c) an information booklet that describes colorectal cancer and screening and d) a particip Primary outcome(s): Rate of FOBT participation per trial arm as assessed by number of FOBT screening tests returned.[At 14 weeks from baseline, 12 weeks after receiving the FOBT.] Study Design: Purpose: Prevention; Allocation: Randomised controlled trial; Masking: Blinded (masking used);Assignment: Factorial;Type of endpoint: Efficacy

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Optimising faecal occult blood screening:retrospective analysis of NHS Bowel Cancer Screening data to improve the screening algorithm.

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