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* = Presenting author

P296 Evaluation of the new liaison faecal calprotectin assay

N. Hammoudi1, H. Manceau2, C. Stefanescu1, D. Debuyser2, Y. Bouhnik1, 3, H. Puy2, 3, K. Peoc’h*2, 3

1APHP HUPNVS Beaujon, Department of Gastroenterology and Nutrition, Clichy, France, 2APHP, HUPNVS, Hopital Beaujon, Biochemistry, Clichy, France, 3Université Paris Diderot, Faculté Xavier Bichat, UMRs INSERM 1149, CRI, Paris, France

Background

Calprotectin is a non-invasive, cheap, and sensitive marker for intestinal inflammation, and its determination in stool is used both in the diagnosis and in the follow-up of patients with inflammatory bowel disease (IBD), and that may avoid or delay colonoscopy, which remains the gold standard. Calprotectin may be measured with commercially available ELISA, EliA assays, and rapid assays in clinical laboratories. Here we describe a new automated CLIA method proposed by DiaSorin for dosing calprotectin in stool, allowing for the organisation of assays as things come, and that we have correlated with the point of care test Quantum Blue (Bühlmann).

Methods

Pre-analytical processing of stool samples was performed manually according to the manufacturer’s recommendations, using stool extraction devices in both cases. The chemiluminescent immunoassay (CLIA) of DiaSorin was used for determination of calprotectin on LIAISON Analyzer (DiaSorin). Samples with calprotectin higher than 800 microg/g of stools were automatically diluted and re-analysed. Results of patients were compared with those obtained with Quantum Blue method, using both low- and high-range kits.

Results

A sample was used to perform within run comparison; the coefficient of variation (CV) around the value of 70 microg/g, which is closed to the cut-off proposed by the manufacturer (50 microg/g), was evaluated to 5%. Quality-control samples were used to assess inter-run comparisons. CVs ranged from 4.6 to 5.9% for values of concentrations of 60 and 240 microg/g for 20 repeats. A total of 53 samples was analysed both with Liaison and Quantum blue. Results obtained with the chemiluminescent immunoassay were lower, but correlated with Quantum Blue values (R2 = 0.9383). Mean values of the whole population were 247 and 534 microg/g with Diasorin and Bulhmann tests, respectively. Clinical data were available for 39 patients. Only patients with values within the range of linearity of both methods were included. As expected, calprotectin was higher in patients presenting ulcerations at colonoscopy (n = 7; mean: 1979 microg/g) than in patients suffering of IBD with no ulcerations (n = 4; mean: 31 microg/g). In our small sample, calprotectin was higher in ulcerative colitis (n = 10; mean: 804 microg/g) than in Crohn’s disease (n = 22; mean: 219 microg/g).

Conclusion

The Liaison immunoassay for measurement of calprotectin in stool was shown to be precise, automated, and associated with active IBD, as confirm by colonoscopy. Further experiments will be needed to establish cut-off values according to the clinical context.