Analytical evaluation of Diazyme procalcitonin (PCT) latex-enhanced immunoturbidimetric assay on Beckman Coulter AU5800

Background: This study was aimed to evaluate the analytical performance of the novel Diazyme procalcitonin (PCT) immunoturbidimetric assay on Beckman Coulter AU5800. Methods: Diazyme PCT is a latex-enhanced immunoturbidimetric assay, developed for use on laboratory instrumentations with capability of reading absorbance at 600 nm. This analytical evaluation included the assessment of limit of blank (LOB), limit of detection (LOD), functional sensitivity, imprecision, linearity, carryover, and method comparison between Diazyme PCT and Kryptor PCT on 129 routine serum inpatient samples. Results: The LOB, LOD, and functional sensitivity of Diazyme PCT were 0.16, 0.26, and 0.28 ng/mL, respectively. The intra-and inter-assay imprecision of Diazyme PCT was between 2.9% and 7.8%. The linearity was excellent in the range of PCT values between 0.16 and 56 ng/mL, and the carryover was negligible (0.02%). A highly significant agreement was found between Kryptor PCT and Diazyme PCT in a range of concentrations between 0.16 and 111 ng/mL (Diazyme PCT = 1.10xKryptor PCT-0.89; r = 0.960; p<0.001). The mean bias was 0.48 ng/mL (95% CI, -0.58 to 1.54 ng/mL). The strength of agreement between Kryptor PCT and Diazyme PCT was between 85% and 96% at 0.50, 2.0, and 10 ng/mL cutoffs. Conclusions: Diazyme PCT appears to be a reliable assay for diagnosis and management of critical care patients susceptible to severe bacterial infections.