Rapid Fecal Calprotectin: CerTest card vs Actim and Calprest ELISA

In patients clinically suspected of inflammatory bowel disease, a head-to-head evaluation compared rapid fecal calprotectin formats—including the CerTest Calprotectin one-step card, an Actim lateral-flow assay, and a Calprest ELISA—using fresh stool specimens processed in parallel, with CerTest and Actim rapid-test results interpreted visually at 10 minutes. The report presents side-by-side sensitivity and specificity estimates, along with inter-method agreement statistics, derived from the same specimen set.

The article describes a prospective, single-center analysis in which 128 fresh stool samples from patients clinically suspected of IBD were tested under identical, parallel conditions across the three assays. Calprest ELISA was treated as the reference method, and a positivity threshold of >40 µg/g was applied per manufacturer instructions; at that cutoff, 47 of 128 samples (36.7%) were ELISA-positive. The primary comparisons focused on how the rapid immunochromatographic card aligned with the ELISA reference and how the two rapid formats aligned with each other under the same run conditions.

Against the ELISA reference at the Calprest ELISA cutoff of >40 µg/g, the CerTest card was reported to have a sensitivity of 87.2% (95% CI, 74.3–95.2) and a specificity of 96.3% (95% CI, 89.6–99.2), with a positive predictive value of 93.2% (95% CI, 81.3–98.6) and a negative predictive value of 92.9% (95% CI, 85.1–97.3). Agreement between CerTest and ELISA was summarized using Cohen’s kappa (κ = 0.85), which the authors described as almost perfect agreement between the visually read rapid card and the quantitative ELISA reference method.

In the same 128-sample parallel analysis, the CerTest card compared with the Actim lateral-flow assay showed a reported sensitivity of 88.0% (95% CI, 75.7–95.5) and a specificity of 100.0% (95% CI, 95.4–100), with Cohen’s κ = 0.90 for agreement. In discussing threshold choices, the authors noted that the 40 µg/g decision limit used for the ELISA in this evaluation is lower than higher, conventional thresholds (for example, around 200 µg/g) often referenced in practice, and they framed threshold selection as a factor that can shift sensitivity and specificity. They also described operational and pre-analytical considerations, including visual interpretation near cutoff levels and the use of freshly collected specimens analyzed promptly (within 24 hours) to minimize handling-related variability.

Key Takeaways:

• The article reports CerTest diagnostic accuracy versus ELISA when the ELISA reference is defined as positive at >40 µg/g in this 128-sample set.
• Cohen’s κ was reported as 0.85 (almost perfect agreement) for CerTest versus ELISA and 0.90 (strong agreement) for CerTest versus Actim.
• Testing was described as parallel across assays on fresh stool samples with 10-minute visual reads for the rapid formats.