Fraser CG, Matthew CM, McKay K, Carey FA, Steele RJAutomated immunochemical quantitation of haemoglobin in faeces collected on cards for screening for colorectal cancer. Gut 57: 1256-1260
Scottish Bowel Screening Centre Laboratory, Kings Cross, Dundee DD3 8EA, UK. Gut
(Impact Factor: 14.66).
05/2008; 57(9):1256-60. DOI: 10.1136/gut.2008.153494
Simple card collection systems are becoming available for faecal immunochemical tests (FITs) as well as guaiac faecal occult blood tests (gFOBTs). FITs are now obtainable that allow quantitation of haemoglobin, so that the analytical detection limit can be set to give a positivity rate that is manageable in terms of the available colonoscopy. A combination of a card collection device and an automated FIT analytical system could be advantageous.
The quantitation of haemoglobin in samples collected on cards with a new analytical system and the relationship between faecal haemoglobin concentration and pathology were investigated in a cohort of gFOBT-positive individuals.
All groups had large ranges of haemoglobin concentration and there was overlap between the groups. Median haemoglobin concentrations in participants with normal findings on colonoscopy (167), diverticular disease (43), hyperplastic polyps (41), low risk adenoma (63), higher risk adenoma (35) and cancer (27) were 13.5, 15.6, 16.8, 15.2, 65.6 and 168.9 ng/ml haemoglobin, respectively. Those with diverticular disease, hyperplastic polyps and low risk adenoma were not significantly different from the normal group (p>0.2), but those with higher risk adenoma had significantly higher concentrations (p<0.001), as did those with cancer (p<0.001). Receiver operating characteristic analysis demonstrates that the cut-off concentration can be set to give appropriate clinical characteristics; optimum sensitivity and specificity are achieved at 26.7 ng/ml.
The haemoglobin in faeces on simple FIT card collection devices can be immunoturbidimetrically analysed quantitatively, and the concentration relates to the presence or absence of significant neoplastic disease.
Available from: Montse Garcia
- "In almost all screening programs, although the FIT result is a quantitative measurement of fecal hemoglobin (f-Hb) concentration, it is used as a binary outcome to identify participants above a predetermined cut-off concentration chosen to suit the requirements of the particular program, such as the colonoscopy resource available. However, there is some evidence that the f-Hb concentration increases during the course of disease development from hyperplastic polyps to cancer (Ciatto et al., 2007; Levi et al., 2007; Fraser et al., 2008; Digby et al., 2013; Liao et al., 2013), which could be useful to stratify the screening population according to individual risk (McDonald et al., 2011). "
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ABSTRACT: The aim of this paper was to examine the distribution of fecal hemoglobin (f-Hb) concentration in a Spanish colorectal cancer screening population according to sociodemographic characteristics and analyze whether f-Hb was associated with clinical outcomes (type of lesion and its location). From September 2009 to November 2012, we sent 77 744 invitations to individuals aged 50-69 years to provide one sample of feces. f-Hb was measured on samples from 27 606 screenees (35.5%). Colonoscopy findings and pathology data were collected on the 1406 screenees with f-Hb greater than 100 ng Hb/ml (20 mg Hb/g feces). The Mann-Whitney U-test and the Kruskal-Wallis test were used to compare f-Hb (median) according to sociodemographic variables, clinical outcomes, and histological features of adenomas. f-Hb from greater than 100 ng Hb/ml was categorized into quartiles. Regression models were used to determine whether f-Hb was a risk predictor of colorectal lesions. f-Hb was associated directly with the severity of the colorectal lesions. An overlap between individuals with a negative colonoscopy and those with a low-risk adenoma was observed. High-grade dysplasia, villous histology, distal location, and increasing size were all features associated with an increased f-Hb level. f-Hb could be used in individual risk assessment to determine surveillance strategies for colorectal cancer screening.
Available from: Jim Chilcott
- "The estimation of sensitivity and specificity of FIT in population-based screening is hampered by the fact that numerous tests are available with heterogeneous performance characteristics, and various approaches have been taken to estimate sensitivity, a criticism that has been made previously (Burch et al, 2007). In addition, although quantitative FITs, theoretically, allow the level to define a ‘positive' result to be set for individual populations and in accordance with local circumstances (e.g. to suit available colonoscopy capacity; Fraser et al, 2008) the absence of high-quality data available at the time we parameterised the models meant that we did not estimate cost-effectiveness of different cut-offs. In effect, we assessed cost-effectiveness at 100 ng ml−1 as this was the cut-off in the key quantitative studies which informed the parameter estimates. "
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ABSTRACT: Several colorectal cancer-screening tests are available, but it is uncertain which provides the best balance of risks and benefits within a screening programme. We evaluated cost-effectiveness of a population-based screening programme in Ireland based on (i) biennial guaiac-based faecal occult blood testing (gFOBT) at ages 55-74, with reflex faecal immunochemical testing (FIT); (ii) biennial FIT at ages 55-74; and (iii) once-only flexible sigmoidoscopy (FSIG) at age 60.
A state-transition model was used to estimate costs and outcomes for each screening scenario vs no screening. A third party payer perspective was adopted. Probabilistic sensitivity analyses were undertaken.
All scenarios would be considered highly cost-effective compared with no screening. The lowest incremental cost-effectiveness ratio (ICER vs no screening euro 589 per quality-adjusted life-year (QALY) gained) was found for FSIG, followed by FIT euro 1696) and gFOBT (euro 4428); gFOBT was dominated. Compared with FSIG, FIT was associated with greater gains in QALYs and reductions in lifetime cancer incidence and mortality, but was more costly, required considerably more colonoscopies and resulted in more complications. Results were robust to variations in parameter estimates.
Population-based screening based on FIT is expected to result in greater health gains than a policy of gFOBT (with reflex FIT) or once-only FSIG, but would require significantly more colonoscopy resources and result in more individuals experiencing adverse effects. Weighing these advantages and disadvantages presents a considerable challenge to policy makers.
Available from: Monique Van Leerdam
- "Immunochemical faecal occult blood testing samples can be analysed automatically, which has important advantages for reproducibility, quality control, capacity, and thus personnel need and costs (Young et al, 2002; Levi et al, 2007). Another advantage of FIT is the quantitative test results, which allows determining an optimal cut-off value for a nation-wide screening programme (Castiglione et al, 2002; Wong et al, 2003; Guittet et al, 2007; Levi et al, 2007; Fraser et al, 2008). The cut-off value for a positive test can be based on a positivity rate that meets the available colonoscopy resources. "
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ABSTRACT: Immunochemical faecal occult blood testing (FIT) provides quantitative test results, which allows optimisation of the cut-off value for follow-up colonoscopy. We conducted a randomised population-based trial to determine test characteristics of FIT (OC-Sensor micro, Eiken, Japan) screening at different cut-off levels and compare these with guaiac-based faecal occult blood test (gFOBT) screening in an average risk population. A representative sample of the Dutch population (n=10 011), aged 50-74 years, was 1 : 1 randomised before invitation to gFOBT and FIT screening. Colonoscopy was offered to screenees with a positive gFOBT or FIT (cut-off 50 ng haemoglobin/ml). When varying the cut-off level between 50 and 200 ng ml(-1), the positivity rate of FIT ranged between 8.1% (95% CI: 7.2-9.1%) and 3.5% (95% CI: 2.9-4.2%), the detection rate of advanced neoplasia ranged between 3.2% (95% CI: 2.6-3.9%) and 2.1% (95% CI: 1.6-2.6%), and the specificity ranged between 95.5% (95% CI: 94.5-96.3%) and 98.8% (95% CI: 98.4-99.0%). At a cut-off value of 75 ng ml(-1), the detection rate was two times higher than with gFOBT screening (gFOBT: 1.2%; FIT: 2.5%; P<0.001), whereas the number needed to scope (NNscope) to find one screenee with advanced neoplasia was similar (2.2 vs 1.9; P=0.69). Immunochemical faecal occult blood testing is considerably more effective than gFOBT screening within the range of tested cut-off values. From our experience, a cut-off value of 75 ng ml(-1) provided an adequate positivity rate and an acceptable trade-off between detection rate and NNscope.
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