Beckman Access versus the Bayer ACS:180 and the Abbott AxSYM cardiac Troponin-I real-time immunoassays: an observational prospective study

BACKGROUND: Reliability of cardiac troponin-I assays under real-time conditions has not been previously well studied. Most large published cTnI trials have utilized protocols which required the freezing of serum (or plasma) for delayed batch cTnI analysis. We sought to correlate the presence of the acute ischemic coronary syndrome (AICS) to troponin-I values obtained in real-time by three random-mode analyzer immunoassay systems: the Beckman ACCESS (BA), the Bayer ACS:180 (CC) and the Abbott AxSYM (AX). METHODS: This was an observational prospective study at a university tertiary referral center. Serum from a convenience sampling of telemetry patients was analyzed in real-time for troponin-I by either the BA-CC (Arm-1) or BA-AX (Arm-2) assay pairs. Presence of the AICS was determined retrospectively and then correlated with troponin-I results. RESULTS: 100 patients were enrolled in Arm-1 (38 with AICS) and 94 in Arm-2 (48 with AICS). The BA system produced 51% false positives in Arm-1, 44% in Arm-2, with negative predictive values of 92% and 100% respectively. In Arm-1, the BA and the CC assays had sensitivities of 97% and 63% and specificities of 18% and 87%. In Arm-2, the BA and the AX assays had sensitivities of 100% and 83% and specificities of 11% and 78%. CONCLUSIONS: In real-time analysis, the performance of the AxSYM and ACS:180 assay systems produced more accurate troponin-I results than the ACCESS system

"You've got it, you may have it, you haven't got it": Multiplicity, heterogeneity, and the unintended consequences of HIV-related tests

This article considers the experiences of health consumers who have undergone testing for human immunodeficiency virus (HIV) antibodies, T cells, and viral load. These HIV-related tests are deployed for the purposes of making definitive diagnoses; yet some test consumers experience ambiguous outcomes. Drawing on an analysis of differing end-user experiences of these tests, where consumers' knowledge reflected the multiplicity and heterogeneity in test design, the author explores how these experiences reflect particular knowledges about these tests. The article contributes to efforts analyzing how health consumers are active end users co-constructing the social meaning of technologies in mutual relationship with other users. The author discusses how this new knowledge can be used to delineate a greater role for consumer evaluation of medical testing within a broader understanding of test design and performance. Relevant links are made to issues such as genetic testing and assessing claims about the efficacy of medical tests