Abstract
Objectives
External quality assessment schemes (EQAS) are being established worldwide to support the faecal immunochemical test (FIT) for haemoglobin (Hb). FIT is widely used as a screening test for colorectal cancer and increasingly in assessment of patients presenting with symptoms. EQA for FIT is provided in several matrices, each unique to the individual scheme. These include Hb suspended in a faecal-like matrix, lyophilised samples and liquid samples. The aim of this study was to evaluate commercially available EQAS and assess their suitability for use.
Methods
Ten EQAS provided material for the study. EQA samples were analysed on four quantitative FIT systems. 15 faecal-like matrix samples were loaded per concentration per FIT system. Reconstituted lyophilised samples were examined five times on three separate occasions and liquid samples were examined 10 times per concentration per FIT system. The coefficient of variation (CV) was calculated per concentration of EQA for each FIT system.
Results
Results from faecal-like matrix schemes had a higher median CV (12.4–19.0%) when compared to those from schemes providing liquid matrices (0.8–2.3%). The spread of CV values was also higher for results from faecal-like matrix schemes with an interquartile range (IQR) 4.4–24.0% vs. liquid IQR range of 0.3–2.5%.
Conclusions
Hb results from faecal-like matrices, whilst more aligned to a patient or participant sample, are prone to pre-examination variation so do not assess the analytical accuracy of a FIT system. Liquid matrices are not prone to pre-examination variation and are better able to assess the accuracy of a FIT system.
Acknowledgments
We thank FIT system suppliers HM-JACKarc: Alpha Laboratories, Eastleigh, Hampshire, UK; OC-SENSOR PLEDIA: Mast Diagnostics; Division, Bootle, Merseyside, UK; SENTiFIT 270: Sysmex UK Ltd, Milton; Keynes, Buckinghamshire, UK; NS-Prime: Alfresa Pharma Corp., Osaka, Japan for supplying the analysers and consumables, and each of the EQA schemes (listed in Table 2) for providing the materials for assessment.
Research funding: None declared.
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
References
1. WHO. Cancer key facts 2018, September 12. Available from: https://www.who.int/news-room/fact-sheets/detail/cancer [Accessed 10 Feb 2020].Search in Google Scholar
2. Saito, H. Colorectal cancer screening using immunochemical faecal occult blood testing in Japan. J Med Screen 2006;13 Suppl 1:S6–7.Search in Google Scholar
3. Navarro, M, Nicolas, A, Ferrandez, A, Lanas, A. Colorectal cancer population screening programs worldwide in 2016: an update. World J Gastroenterol 2017;2:3632–42. https://doi.org/10.3748/wjg.v23.i20.3632.Search in Google Scholar PubMed PubMed Central
4. National Institute for Health and Care Excellence. Quantitative faecal immunochemical tests to guide referral for colorectal cancer in primary care. Diagnostics guidance DG30. Available from: https://www.nice.org.uk/guidance/dg30 [Accessed 05 Feb 2020].Search in Google Scholar
5. ISO 15189:2012. Medical laboratories - Requirements for quality and competence. Geneva: ISO Publications; 2012.Search in Google Scholar
6. Benton, SC. IFCC – FIT working group (FIT-WG). IFCC e-news 2017:16–7. Available from: https://www.ifcc.org/media/461890/IFCCeNewsJune2017.pdf [Accessed 03 Feb 2020].Search in Google Scholar
7. Piggott, C, Shugaa, Z, Benton, SC. Independent internal quality control (IQC) for faecal immunochemical tests (FIT) for haemoglobin: use of FIT manufacturers’ IQC for other FIT systems. Clin Chem Lab Med 2021;59:e41–3. https://doi.org/10.1515/cclm-2020-0286.Search in Google Scholar PubMed
8. Fraser, CG, Allison, JE, Halloran, SP, Young, GP. A proposal to standardize reporting units for fecal immunochemical tests for hemoglobin. J Natl Cancer Inst 2012;104:810–4. https://doi.org/10.1093/jnci/djs190.Search in Google Scholar PubMed
9. Whitehead, TP, Browning, DM, Gregory, A. A comparative survey of the results of analyses of blood serum in clinical chemistry laboratories in the United Kingdom. J Clin Pathol 1973;26:435–45. https://doi.org/10.1136/jcp.26.6.435.Search in Google Scholar PubMed PubMed Central
10. UK NEQAS. Faecal markers of inflammation 2019. Available from: https://ukneqas.org.uk/programmes/result/?programme=faecal-markers [Accessed 03 Feb 2020].Search in Google Scholar
11. Roseth, AG, Fagerhol, MK, Aadland, E, Schjonsby, H. Assessment of the neutrophil dominating protein calprotectin in feces. a methodologic study. Scand J Gastroenterol 1992;27:793–8. https://doi.org/10.3109/00365529209011186.Search in Google Scholar PubMed
12. Mellen, S, de Ferrars, M, Chapman, C, Bevan, S, Turvill, J, Turnock, D. Evaluation of sample stability for a quantitative faecal immunochemical test and comparison of two sample collection approaches. Ann Clin Biochem 2018;55:657–64. https://doi.org/10.1177/0004563218766393.Search in Google Scholar PubMed
13. Ostrow, JD. Tests for fecal occult blood. In: Walker, HK, Hall, WD, JW, H, editors. Clinical methods: the history, physical, and laboratory examinations. 3rd ed. Boston: Butterworths; 1990, Chapter 98.Search in Google Scholar
14. Brown, LF, Fraser, CG. Effect of delay in sampling on haemoglobin determined by faecal immunochemical tests. Ann Clin Biochem 2008;45:604–5. https://doi.org/10.1258/acb.2008.008024.Search in Google Scholar PubMed
15. Fraser, CG, Benton, SC. Detection capability of quantitative faecal immunochemical tests for haemoglobin (FIT) and reporting of low faecal haemoglobin concentrations. Clin Chem Lab Med 2019;57:611–6. https://doi.org/10.1515/cclm-2018-0464.Search in Google Scholar PubMed
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