Determining procalcitonin at point-of-care; A method comparison study of four commercial PCT assays.

OBJECTIVE: Procalcitonin (PCT) testing adds value in the early detection of infection and sepsis, as well as in management of antibiotic therapy. We determined the analytical and diagnostic performance of four PCT assays at POC. METHODS: PCT assays on AQT90 FLEX, Getein 1100, mLabs, and Finecare POC analyzers, in whole blood and plasma, were analyzed for repeatability, linearity, accuracy and concordance, by comparing with our reference PCT assay on the Cobas E602 system. RESULTS: For all assays precision was found higher in plasma than in whole blood. AQT90 showed good performance in all analytical and diagnostic areas, irrespective of test matrix and PCT concentration. The other POC assays demonstrated at least one analytical weakness. The Getein assay showed adequate precision only in plasma at high PCT levels, the mLabs assay only in plasma at low PCT levels. Accuracy, as demonstrated by Bland-Altman and Passing-Bablok analysis, was found adequate only for the AQT90 FLEX and Getein 1100 assay. Diagnostic concordance at 0.5 â€‹ng/mL was found excellent for the AQT90 FLEX, Getein 1100, and Finecare assays, much lower for the mLabs assay. At 0.25 â€‹ng/mL, only the AQT90 FLEX and Finecare assays showed excellent concordance with the reference assay. CONCLUSIONS: The AQT90 FLEX PCT assay demonstrated excellent analytical performance and diagnostic agreement with the Cobas E602 assay, allowing both stand-alone and side-by-side testing. The other assays demonstrated some analytical deficiencies, potentially limiting their diagnostic use. Any clinical use of PCT results should always be in combination with all other clinical signs and diagnostic information.

[Determination of procalcitonin (PCT) in micro-method on AQT90 FLEX® analyzer and in vitro stability study]. / Dosage de la procalcitonine (PCT) en microméthode sur analyseur AQT90 FLEX® et étude de la stabilité in vitro.

Radiometer® has developed a point-of-care test for fast PCT measurement on whole blood in micromethod on a AQT90 FLEX® instrument. We have verified the analytical performances of the AQT90 FLEX® PCT assay in heparinized macrotube and EDTA microtube for pediatric use, according to modified French Society of Clinical Biology (SFBC) protocol to the requirements of the standard NF EN ISO 15189: 2012. The samples (n=61, 30 macrotubes, 31 microtubes) were analyzed by the Brahms Kryptor Compact Plus® reference method vs the AQT90 FLEX®. In a second step, we studied the stability of the PCT at room temperature for 24 h. A good correlation between the two methods on macro- or microtubes is observed (respectively r=0.990 and 0.993). The Bland-Altmann representations confirm the excellent correlation with a deviant, above the acceptable limit, which was calculated according to ISO 5725-6, for each type of tube and for the two concentration ranges (lower and greater than 1 ng/mL). The biases observed do not affect the clinical decision. No degradation of PCT after 24 h was demonstrated by the Mann and Whitney test on macro- and microtubes (p=0.50 and 0.34, respectively). The determination of PCT on AQT90 FLEX® has satisfactory analytical characteristics and can be used as point-of-care testing device on whole blood without pre-analytical treatment. In heparinized macrotube and EDTA microtube, the PCT is stable at room temperature up to 24 h.

Clinical performance of cardiac Troponin I: A comparison between the POCT AQT90 FLEX and the Dimension Vista analyzer in an emergency setting.

BACKGROUND: Cardiac troponin [cTn (I or T)] is the preferred biomarker for the diagnosis of myocardial infarction (MI). AIM: We studied the analytical performance of the POCT AQT90 FLEX cTnI assay and its diagnostic accuracy, in comparison to the Dimension Vista cTnI method, in patients presenting to the Emergency Department (ED) with suspect of acute coronary syndrome (ACS). METHODS: 786 consecutive patients were enrolled. cTnI was measured at admission to the ED and about 3 and 6 hours later. The imprecision study was carried out using different lots of quality controls (QCs). ROC curve analysis was conducted using discharge diagnoses in order to verify the global diagnostic accuracy. RESULTS: The concentrations measured in the QCs ranging from 0.033 to 1.26µg/L show CVs% ranging from 2.81 to 7.56%, comparable to those declared by the manufacturer. Passing-Bablok and linear regression analysis show a high significant correlation (R2=0.90, p<0.0001); Bland-Altman test describes a statistically significant negative bias (Bias=-0.2336; 95%CI=-0.4217/-0.0456, p=0.0150). ROC curves obtained using Dimension Vista and AQT90 FLEX cTnI assays displayed similar clinical performance being not statistically significant the difference of the corresponding AUC. Comparing sensitivity and specificity of cTnI concentrations obtained from the ROC curve analysis using AQT90 FLEX, we found a "best cut-off" (0.014µg/L) lower than that declared from the manufacturer (0.023µg/L). CONCLUSIONS: The comparison of two different assays of cTnI against a diagnosis of acute MI (AMI) shows that both assays behave equally well with a high degree of sensitivity and specificity. The resulting "best cut-off" suggests that this AQT90 FLEX cTnI concentration could be evaluated as the potentially new "clinically usable" cut-off for AMI/myocardial necrosis diagnoses.