A-004 Analytical Assessment and Expanded Stability Studies of the Abbott Alinity i STAT High Sensitivity Troponin-I Assay
Authors: Kirchhoff D C , Arowolo F K , Pinero G M , Mendu D R 
Published: September 2023

Abstract

Background
The Mount Sinai Health System has recently integrated the Abbott Alinity i STAT High Sensitivity Troponin-I Assay (HS-Trop) into its “Suspected Acute Coronary Syndrome Algorithm”. Prior to doing so, a comprehensive evaluation of the assay was performed. In particular, the manufacturer’s specifications state that HS-Trop samples (plasma) are stable for 8 h at room temperature (RT), and that plasma and red cells must be separated by centrifugation within 30 min of draw. This centrifugation time window and RT storage requirements are not practical for most large hospital laboratories. Sample delivery, accessioning, and centrifugation are often greater than 30 min, and in most laboratory automation systems, sample storage modules are refrigerated. RT storage would require the removal of the HS-Trop sample from the automation line, and storing the sample elsewhere. This adds additional work to laboratory staff, and makes add-on testing challenging. As such, refrigerated storage and a longer centrifugation time window would be ideal. In this study, we sought to assess the analytical performance of the HS-Trop assay, and validate expanded centrifugation and stability requirements.

Methods
Inter and Intraday precision was assessed through replicate measurements (n = 10) of low, mid, and high Technopath Quality Controls. Linearity was determined through triplicate analysis of Maine Standards linearity standards. Accuracy was assessed through split sample (n = 40) analysis on two distinct reagent lots. Stability was assessed in centrifuged samples at RT and 4 °C through analysis at 0, 4, and 8 h time points, with an additional 16 h time point assessed at 4 °C. Unspun sample stability was assessed at RT at 0, 2, 4, and 8 h time points. LoQ was assessed through a sensitivity profile, by performing a serial dilution spanning 1:2–1:128, measuring each dilution in triplicate on 10 different days. Reference range verification was performed through the assessment of 20 sex-stratified normal donor samples.

Results
Intraday precision afforded CVs of 5.1%, 5.6%, and 2.9% for the low, mid, and high controls, respectively, while Interday precision at low, mid, and high controls yielded CVs of 4.3%, 6.3%, and 3.3%. Accuracy assessment resulted in a slope of 0.928, y-intercept of 6.613, and R2 = 0.9943. Linearity was confirmed between 12.3 and 4216.5 ng/mL with a slope of 0.997, y-intercept of 0.261. Spun and Unspun sample stability was confirmed at RT and 4 °C for a maximum of 8 h, affording percent difference values with respect to the initial time point of &lt;20%. Stability studies failed at the 16 h time point. The LoQ was determined to be 4.4 ng/L at 20% CV. The reference range was verified at: Males, &lt;34, and Females, &lt;18 ng/L.

Conclusions
Our study has shown the Abbott HS-Trop assay performs well analytically, with acceptable precision, accuracy, linearity, and analytical sensitivity for the assessment of HS-Trop. The manufacturer-specified reference range was confirmed. Our study has validated and confirmed an expanded stability and centrifugation window, which will allow for the easy integration of the assay into large hospital networks, and for its use in many laboratory automation systems.