Background: Fecal calprotectin is a valuable non-invasive marker for intestinal inflammation and contributes to the selection of patients with suspected inflammatory bowel disease (IBD) for endoscopy. The aim of this study was to evaluate the performance of three automated immunoassays for fecal calprotectin (FC), fecal lactoferrin (FL) and fecal alpha-1-antitrypsin (A1AT) for diagnosis and follow-up of IBD, to investigate if automated analysis of this biomarker profile may further improve the diagnostic process, and to compare them to manual ELISA tests from different manufacturers.
Methods: Stool samples from 72 patients with Crohn’s disease (42), ulcerative colitis (17), irritable bowel syndrome (5), other gastrointestinal inflammation (8), and 72 healthy controls were analyzed for FC, FL, and A1AT on the automated Alegria® system (ORGENTEC Diagnostika, Germany). The results were verified by commercially available manual ELISA tests and discrepancies were further analyzed by immunoblotting. The fecal test results were correlated with the patients’ endoscopic findings and with disease activity.
Results: The automated assays FC and FL for Alegria® detected endoscopically active intestinal inflammation with a sensitivity and specificity of 74% and 87% (FC) and 62% and 87% (FL), respectively, and efficiently discriminated IBD from non-IBD samples in the patient cohort. Healthy controls tested negative in all assays.
The results of the automated biomarker assays significantly correlated to those of the manual ELISAs. Alegria® results for FC were confirmed by immunoblotting in 7 discrepant samples.
Levels of A1AT out of the normal range were detectable in a substantial number of IBD and irritable bowel syndrome (IBS) samples: 50% Crohn’s disease, 35% ulcerative colitis, and 60% IBS, reflecting the disease-related changes of intestinal permeability in these patients. In IBD patients, elevated levels of A1AT correlated with relapsing disease.
Conclusions: Measurement of FC concentrations with Alegria® is a convenient, promising, and useful tool for improving laboratory diagnostic accuracy and accelerating the diagnostic process and helps to identify those patients in whom endoscopy may be avoided. Automated analysis of a comprehensive profile of fecal biomarkers with Alegria®, including A1AT, provides further substantial benefit for laboratory diagnostics of IBD by improving stratification of patients for treatment and care.