NEW FAECAL CALPROTECTIN ASSAY BY IDS: VALIDATION AND COMPARISON TO DIASORIN METHOD

Background
Faecal Calprotectin measurement is a non-invasive test used for the diagnosis and follow-up of inflammatory bowel disease (IBD), and its differentiation with irritable bowel symptom (IBS). IDS developed a new kit for stool extraction and Calprotectin measurement.
Objective
The aim of this study was to validate the IDS Calprotectin extraction device and immunoassay kit, and to compare it with the DiaSorin Liaison test in patients with known clinical status.
Methods
Precision was evaluated on 5 native samples measured 5 days in pentaplicate after extraction. Stability at 2-8°C and -20°C were assessed for 7 days and 14 weeks, respectively. A lot to lot comparison was also performed. Finally, a total of 379 stool extracts were analysed with the IDS kit on iSYS, and compared with DiaSorin Liaison assay. Clinical data of these patients about IBD/IBS were collected.
Results
Intra and inter-assays CV ranged from 1.8% to 3.0%, and 2.5% to 4.1% respectively, for the tested ranges (39.6 to 1545.8 µg/g). Samples could be stored for up to 4 days at 2-8°C, and up to 4 weeks at -20°C. Lot to lot comparison showed a good correlation (Lot1 = 1,0Lot2 + 31.8 ; p>0.05). The Passing and Bablok regression showed no significant deviation from linearity between the two methods (IDS = 1.06DiaSorin – 0.6; p>0.05). According to the recommended cut-offs (<50µg/g:negative ; 50-120:equivocal ; >120:positive), the IDS assay identified more IBD and IBS patients than DiaSorin, which had more borderline results (17 vs 20%, respectively). Similarly, using a 250µg/g cut-off, widely used among physicians, the IDS method detected more patients with IBD.
Conclusion
The IDS fecal Calprotectin had good analytical validation parameters. Compared to the DiaSorin method, IDS calprotectin assay showed comparable results, but outperformed it in the identification of more IBD patients.
Disclosures
EC is an accountant for both IDS and Diasorin.