Evaluation of a fluorescent immunochromatography test for fecal calprotectin

BACKGROUND: Fecal calprotectin (FC) is widely used to discriminate between patients with inflammatory diseases such as inflammatory bowel disease (IBD) and functional diseases such as irritable bowel syndrome (IBS). ELISA is a time‐consuming method for the measurement of FC, whereas a fluorescent immunochromatography test can obtain results in around 30 minutes and thus enables a rapid response to clinical decision. METHODS: Two methods, the Proglead(®) calprotectin (FC Proglead) and the BÜHLMANN fCAL(®) ELISA (FC BÜHLMANN), were used to quantitatively examine FC in 111 stool samples. The comparison and bias estimation of both assays were assessed using CLSI EP09c protocol. RESULTS: The two methods were highly correlated (rho = .96). Deming regression was employed to calculate the regression equation, with a slope of 1.01 and an intercept of −4.98 μg/g. The estimated median bias (FC Proglead − FC BÜHLMANN) was −4.19 μg/g with the 95% limits of agreement (−55.59 to 47.21 μg/g), and the estimated median percent bias was −8.71% with the 95% limits of agreement (−50.31% to 32.90%). There was 4.50% (5/111) of values outside the 95% limits of agreement. Percent biases at the FC cutoff values of 50 and 200 μg/g between both methods evaluated by Deming regression were 8.96% and 1.49%, respectively. The biases were all less than the acceptable standard (10%). And, 99.10% of FC results were in agreement between both methods (kappa = .99, P < .001). CONCLUSIONS: FC Proglead may be used as a suitable alternative to FC BÜHLMANN for the disease activity assessment for patients with IBD, considering its convenience and shorter turnaround time.