A-017 Clinical Verification on VITROS hs Troponin I Assay Hook Effect

Abstract Background In the past decades, clinicians favored more on lower cardiac troponin detection capability to find micro-myocardial injury. In another clinical scenario, for patients who need coronary artery bypass grafting (CABG), TnI concentration may increase higher than 75 times URL or even above. For these patients, analytical performances of high concentration TnI will be more important (ULLI, upper limit of linearity, and ect.,). Meantime, in order to avoid high dose TNI resulting false negative, hook effect need to be established and validated. In our laboratory, we use VITROS 5600 system detecting hsTnI. In reagent’s IFU, it declares that no hook effect interference is found while hsTIN up to 100000 ng/L. In order to meet clinicians’ high dose scenario’s needs (like CABG), based on EP06-A3, EP10-A3, according to our laboratory’s quality system, we verify Vitros high-sensitivity TnI hook effect besides other analytical performances. Methods Endogenous cTnI was spiked into a human matrix, containing no measurable cTnI. The concentration of cTnI was determined to be near to 100,000 nanograms per liter (ng/L) using the gravimetric method and then diluted to create a panel of ten samples ranging from 0 to near 100,000 ng/L (a total of twelve samples). The high dose hook fluids were tested in triplicate using three VITROS hsTnI reagent lots one VITROS 5600. The operation circumstances on each working day were well controlled, each reagent lots were successfully calibrated and calibration quality parameters are reported with the QC In-house Control results. The signal (ALUs) for each sample on each reagent Lot were plotted against the dose concentration of the sample to assess hook effect. If the signal begins to decrease as the concentration increases, there occurs a hook effect. The acceptance criteria are that there is no high dose hook effect up to near 100,000 ng/L, which means the light units for the high dose fluids up to near 100,000 ng/L must be read greater than the light signal at the top of the assay upper limit of linearity range (30,000 ng/L). Results All in house QCs and calibration quality parameters were within the laboratory’s acceptance Limits. There were no invalid or excluded results in this study. All VITROS hsTnI In-house controls and calibration quality parameters were within our laboratory’s acceptance Limits. The highest sample was calculated at 98,060 ng/L (D1), along with three consecutive high-value samples, had concentrations exceeding the assay*s linearity range (1.50 – 30,000 ng/L). Their light units exceeded those of the calculated signal for the top end of the measuring range and their calculated concentrations exceeded 30,000 ng/L. Conclusion No high dose hook was observed across all samples tested. There was no evidence of high dose hook observed for the test fluids up to a concentration of 98,060 ng/L. This met the IFU declared hook effect analytical performance. We conclude that for patients who has complex clinical procedures, such as CABG, VITROS hsTnI on 5600 in our laboratory will not give a false negative result till TnI above 3 times ULLI.