Verification of the Bühlmann fCAL turbo faecal calprotectin assay on the Binding Site Optilite benchtop analyser

Abstract

Objectives: Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are increasingly prevalent disorders. Faecal calprotectin is useful in the differential diagnosis of IBD from IBS and monitoring IBD activity. We verified the Bühlmann fCAL turbo faecal calprotectin assay on the Binding Site, Optilite benchtop analyser. Design: Accuracy, precision, lower limit of quantitation (LLoQ), and linearity of the Bühlmann fCAL turbo faecal calprotectin assay on the Binding Site, Optilite benchtop analyser were ascertained. Comparison with the Bühlmann Quantum Blue fCAL extended and DiaSorin, Liaison calprotectin assays were also undertaken. Difference between assays was evaluated using the Wilcoxon signed-rank test and method comparison was undertaken using Spearman’s rank correlation (rs), difference plots and Passing-Bablok regression analyses. Results: The fCAL turbo assay was linear between 25 and 10,000 μg/g, and the LLoQ was 25 μg/g. Intra-, and inter-assay imprecision was <5%. There was a good agreement (rs = 0.96) and no significant bias (3%, p = 0.10) present between the fCAL turbo and Quantum Blue extended assays. Between the fCAL turbo and DiaSorin, liaison assays there was a good agreement (rs = 0.97), but a significant bias (53%, p = <0.01) was present. Conclusions: The fCAL turbo assay performs well on the Binding Site, Optilite benchtop analyser. Calprotectin results are commutable between with Bühlmann fCAL turbo and Quantum Blue fCAL extended assays, but not between Bühlmann and DiaSorin calprotectin assays.

Keywords

• Calprotectin
• Faeces
• Inflammatory bowel disease
• Inflammatory bowel syndrome
• Method validation