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Introduction Faecal calprotectin (FCP) testing is recommended as an option to support clinicians with the differential diagnosis of inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS), in adults with recent onset lower gastrointestinal symptoms, for whom specialist assessment is being considered.A service evaluation study was set up to investigate if the OC Sensor Pledia system (OC-FCa) can be used as alternative assay to CALPRO2 currently in routine use.Methods Faecal samples, received into the laboratories in stool specimen containers from patients undergoing routine testing for FCP, were subsampled into the OC-Sensor auto-sampling bottle (MAST-Group). Samples were tested for FCP using both methodologies (OC-FCa and CALPRO2) according to manufacturer’s protocols.Data from both assays was collected and linked to clinical outcomes from NUH systems to look for any IBD diagnoses within 90 days following the test. This linked dataset was then used as the basis for analysis and concordance of results.A positive/negative correlation of results (based on thresholds of 100 µg/g and 500 µg/g for the OC-FCa assay and 50µg/g and 250 µg/g for the CALPRO2 assay were then attributed to the dataset.The service evaluation study was registered as a clinical audit 24-658C within NUH.Results 895 samples (from 862 patients) were available for analysis. Within the cohort, 27 samples (25 patients) had a diagnosis of IBD.Concordance of FCP data showed an approximate 2x increase in FCP results seen with the OC-FCa assay compared to CALPRO2.An overall agreement of 86.1% for all samples was seen based on the 100ug/g FCP (OC-FCa) vs 50ug/g (CALPRO2) thresholds; and 94.0% based on 500ug/g (OC-FCa) vs 250ug/g (CALPRO2) thresholds, indicating that the majority of sample classifications were consistent across both methods.Within the IBD cohort the assays had an overall agreement of 96.5% at thresholds of 100ug/g for OC-FCa and 50ug/g CALPRO2 (Cohen’s Kappa-0.9), and 77.8% at the higher thresholds.Conclusions While the level of agreement appears high with this study, the small proportion of discordant results should be investigated further to understand any systematic differences, particularly in borderline or challenging samples.The number of IBD patients in this study is low, however there appears to be sufficient concordance to assure secondary care that a switch in the method for analysis of faecal calprotectin could be approved, following a change in cut-offs triggering a referral and communication to GPs and patients.Additional studies are underway comparing samples taken directly into the sampling devices, with those from faecal samples in universals, from patients with known IBD to increase confidence in the assay and assess patient and clinical teams’ acceptance.Abstract P207 Figure 1