Liver function testing on the Abaxis Piccolo Xpress: Use in Ebola virus disease protocols.

Background: Laboratories that choose a point-of-care approach for liver function testing in patients undergoing evaluation for Ebola virus disease (EVD) have few options to choose from. The primary objective of this study was to conduct a performance characterization of a Clinical Laboratory Improvement Amendments (CLIA)-waived liver function panel on the Abaxis Piccolo® Xpress chemistry analyzer. The secondary objectives were to evaluate multiple specimen types, characterize whole blood specimen stability, and validate disposable exact transfer pipettes. Our final objective was to assess instrument airflow from a biosafety perspective.

Methods: An instrument performance characterization, including precision, linearity, accuracy, reference interval verification, and specimen type evaluation was conducted using Liver Panel Plus reagent discs on the Piccolo® Xpress.

Results: All assays demonstrated acceptable linearity (slopes, 0.938-1.061; observed error, 0.8-6.3%). Assay precision was 0.0-3.6% (%CV; within-day studies) and 0.9-5.6% (between-day studies). Method comparison experiments (versus Roche cobas c502/c702 chemistry analyzers) showed excellent correlation for most assays, although a few notable differences were observed (Piccolo versus Roche): alkaline phosphatase, -18.6%; amylase, -29.0%; total bilirubin, +0.3mg/dl. Pre-programmed reference intervals were verified except for the alkaline phosphatase (male and female) and alanine aminotransferase (female), which had greater than 10% of results fall below the programmed ranges. Piccolo instrument results were largely consistent across specimen types tested (lithium-heparin whole blood, lithium-heparin plasma, and serum), although some statistical differences were observed for aspartate aminotransferase, gamma glutamyltransferase, and total protein. Whole blood time course studies demonstrated that some analytes (albumin, amylase, and total protein) showed remarkable stability, while others (such as aspartate aminotransferase) showed a slight trend toward decreased activity over time. Exact volume transfer pipettes provided an effective disposable option for disc loading. Finally, airflow studies suggested that, in the context of EVD protocols, instrument placement in a biosafety level (BSL) 2 cabinet or greater is justified.

Conclusions: Given its analytical performance and ease of operation, the Piccolo Xpress was transferred to a BSL-2 cabinet in our BSL-3 suite for use in our hospital's diagnostic protocol for providing liver function testing in patients undergoing evaluation for EVD.