Comparative evaluation of fecal calprotectin and S100A12 as non-invasive markers for disease activity in inflammatory bowel disease

Introduction: This study was aimed to evaluate the diagnostic accuracy of fecal S100A12, and fecal calprotectin in adult patients with irritable bowel syndrome (IBS) and active or inactive inflammatory bowel disease (IBD). As some authors suppose the use of higher cutoff levels for an improved discrimination of active from inactive IBD, different cutoff-levels were compared with endoscopic disease activity.

Methods: Fecal levels of calprotectin and S100A12 were assessed by enzyme linked immunosorbent assay in 210 patients (78 IBS patients, 54 with UC, and 78 with 43 CD). The performance of each marker with reference to the endoscopic inflammatory activity was assessed by calculating sensitivity, specificity and accuracy using published as well as adjusted cutoffs.

Results: Diagnosis as well as the activity state (active or inactive) and the corresponding results of fecal assay results are as shown in Table 1 for calprotectin and Table 2 for S100A12. Using adjusted cutoffs (from 50 to 75µg/ml for calprotectin and from 1 to 1.5µg/ml for S100A12) enabled a marked improvement of the specificity of all markers in discriminating active from inactive IBD.

Tab.1: Calprotectin

	Spezifität		Sensitivität		Diagnostische Genauigkeit
Calprotectin	Cut-Off 50µg/ml	Cut-Off 75µg/ml	Cut-Off 50µg/ml	Cut-Off 75µg/ml	Cut-Off 50µg/ml	Cut-Off 75µg/ml
Kontr. (n=78) vs. IBD aktiv (n=94)	87,18%	88,46%	96,81%	92,55%	92,44%	90,70%
Kontr. (n=78) vs. CU aktiv (n=43)	87,18%	88,46%	93,02%	90,70%	89,26%	89,26%
Kontr. (n=78) vs. MC aktiv (n=51)	87,18%	88,46%	100%	94,12%	92,25%	90,70%
IBD aktiv (n=94) vs. IBD Rem. (n=38)	65,00%	76,32%	96,81%	92,55%	87,31%	87,88%

Tab.2: S100A12

	Spezifität		Sensitivität		Diagnostische Genauigkeit
S100 A12	Cut-Off 1µg/ml	Cut-Off 1,5µg/ml	Cut-Off 1µg/ml	Cut-Off 1,5µg/ml	Cut-Off 1µg/ml	Cut-Off 1,5µg/ml
Kontr. (n=78) vs. IBD aktiv (n=94)	74,24%	81,82%	98,82%	96,47%	88,08%	90,07%
Kontr. (n=78) vs. CU aktiv (n=43)	74,24%	81,82%	100%	100%	83,81%	88,57%
Kontr. (n=78) vs. MC aktiv (n=51)	74,24%	81,82%	97,83%	93,48%	83,93%	86,60%
IBD aktiv (n=94) vs. IBD Rem. (n=38)	47,06%	52,94%	98,82%	96,47%	84,03%	84,03%

Conclusion: The fecal markers calprotectin and S100A12 are reliable markers for the differentiation of IBD from IBS. As supposed by some authors, higher cuttoffs for both markers improve diagnostic accuracy for discriminating active from inactive IBD.