P305 Normal reference ranges and cut-off values for considering and performing endoscopy using the Sentinel CaliaGold® Calprotectin assay
Schoorl, M.(1)*;Beugelink, T.(1);Grasman, M.E.(2);Jongbloed, W.(1);
(1)Noordwest Ziekenhuisgroep, Clinical Chemistry- Haematology & Immunology, Alkmaar, The Netherlands;(2)Noordwest Ziekenhuisgroep, Gastroenterology, Alkmaar, The Netherlands;
Fecal calprotectin, a calcium-binding protein, is used as a sensitive marker for gastrointestinal mucosal inflammation. It is a simple, non-invasive test that can be used to differentiate irritable bowel syndrome (IBS) from inflammatory bowel disease (IBD), where there can be significant overlap in clinical symptoms. Recently, Sentinel Diagnostics launched a new CALiaGold® pierce Tube in combination with a new latex immunoassay for calprotectin measurement on the SENTiFIT® 270 analyzer.
The aim of the study is to evaluate the current used normal reference range for calprotectin <60 µg/g*) and the current used cut-off values for considering and performing an endoscopy in case of IBD (considering endoscopy: calprotectin 60-250 µg/g*, performing endoscopy: calprotectin >250 µg/g*).
Patients received the CALiaGold® pierce Tube (Sentinel, ref. 1151300) along with the instruction protocol for stool collection at home. Within two days after fecal sampling, calprotectin was measured with the corresponding Quantitative Calprotectin latex immunoassay (Sentinel, REF 115100) on the SENTiFIT® 270 analyzer.
Endoscopies were performed within one month around the fecal collection. Results of the endoscopies were registered and interpreted by the gastroenterologist. Calprotectin results were classified according to the clinical diagnosis.
In total 438 symptomatic patients participated in the study (163 men, age 18-83 and 275 female, age 18-90): 239 with active inflammatory bowel disease, 43 with IBD in clinical remission, 43 with IBS, 17 with other intestinal diseases and 96 controls without identified intestinal disease.
The normal reference range for calprotectin was established as <70 µg/g (= p5 positive samples) and the cut-off for performing endoscopy as >355 µg/g (= p95 negative samples). The range 70-355 µg/g calprotectin can be used for considering an endoscopy. Using the new reference range, sensitivity and specificity was calculated as 92% and 93%, respectively. The negative predictive value (NPV) and positive predictive value (PPV) were calculated as 88% and 95%.
Using the routinely used reference range (<60 µg/g calprotectin) a 95% sensitivity, 86% specificity, 90% NPV and 92% PPV was established.
In case of stool collection at home with the CALiaGold® pierce Tube, the Sentinel CaliaGold® Calprotectin assay is highly sensitive in detecting mucosal inflammation.
To differentiate between IBS and IBD, it is recommended to adjust the cut-off for differential diagnosis to 70 µg/g calprotectin. In case of IBD monitoring, it is recommended to adjust the cut-off for endoscopy to >355 µg/g calprotectin to reduce the risk of relapse.
* Ref.: Nederlandse Vereniging van Maag-. Darm- en Leverartsen, oktober 2015