Clinical performance of a particle enhanced turbidimetric immunoassay (PETIA) for detecting fecal calprotectin

Particle-enhanced turbidimetric immunoassay (PETIA) is a new measurement procedure for detecting fecal calprotectin (FC). We aimed to investigate the accuracy and clinical performance of PETIA for FC. We assessed the accuracy of PETIA for FC measurements through concordance analysis, Passing-Bablok regression and Bland-Altman analysis, using enzyme-linked immunosorbent assay (ELISA) as the reference. To evaluate the clinical performance of PETIA, the FC levels of individuals with significant and non-significant bowel diseases were compared. The receiver operating characteristic (ROC) analysis was performed to determine the appropriate cut-off value of FC detected by PETIA for discriminating subjects with significant and non-significant colorectal lesions. Of the 413 cases analyzed, 340 (82.3%) were concordant between PETIA and ELISA. No significant discordance was observed. There was a good agreement (y = -7.710+0.957x) between PETIA and ELISA for detecting FC. The FC level detected by PETIA in patients with significant bowel diseases (159.1 [31.3, 821.0] µg/g) was significantly higher than that of subjects with non-significant bowel diseases (10.3 [4.2, 38.5] µg/g) (p < 0.001). The AUC of FC for identifying significant bowel diseases detected by PETIA was 0.82 (p < 0.001). With a cut-off value of 77.6µg/g, the specificity and positive predictive value were 92.2% and 97.1%, respectively. The PETIA for FC measurement showed good clinical performance for detecting bowel diseases.