We believe that we have described in this study a way to improve the sensitivity of point of care assays for troponin that allows us to identify additional patients without losing the specificity required to identify appropriate patients for discharge from the emergency department.Įarly and accurate diagnosis of a specific disease plays a decisive role for its effective treatment. Clinical review showed POC tests missed 6 of 13 patients with confirmed AMI (a sensitivity of 46%) and that a lower cut-off allowed them to detect all (for the i-stat) or most (4 of 6 for the AQT) of them. Using a decreased cut-off (50% of 99 th percentile) increased detection of true positives (to 80.9 and 76.5%) with an acceptable rate of false positive results (7.3 and 7.1%) significantly (P<0.01). ![]() Clinical outcomes were obtained for patients with elevated levels of the laboratory assay.Īt the 99 th percentile both assays did only detect cardiac injury in a percentage of true positives compared to the laboratory test (34 and 51%) with a significant rate of false negative values (19.6 and 14.9%). We used chi-square tests for the comparison and a P<0.05 as significant. We investigated these tests in a convenience sample of 195 patients presenting to a suburban hospital. We used the published 99 th percentile and a value that was 50% of that. We compared 2 point of care assays (i-stat, Abbott Diagnostics and AQT 90, Radiometer) for troponin I with a laboratory assay for troponin I (ARCHITECT STAT troponin-I assay, Abbott Diagnostics), previously evaluated for diagnosis of acute coronary syndrome (ACS). In a prospective study we evaluated a decreased cut-off in the detection of cardiac injury. Troponin point of care tests have been found to have inferior sensitivity to laboratory based tests, when either the 10% CV or the 99 th percentile of a healthy population is used as the cut-off. The i-STAT cTnI assay is a sensitive and precise monitor of cTnI, poised for point-of-care/near bedside clinical utilization for triage, diagnostics and risk management of acute coronary syndrome patients. Regression analysis for the i-STAT cTnI between whole blood and plasma specimens and for whole blood between the i-STAT and Stratus CS cTnI assays demonstrated slopes of 1.06 and 0.89, respectively. ![]() ![]() An equimolar response within 5% was found for reduced and phosphorylated forms of TIC and IC complexes. The assay was not affected by common interferents. The 99th percentile reference limit was 0.08 microg/l. Total imprecision (CV) of 10% and 20% were seen at 0.09 and 0.07 microg/l, respectively. Factors studied included antibody specificity, detection limit, imprecision, linearity, assay specificity, sample type stability, interferences, reference limit determination and comparison vs. A total of 186 whole blood specimens (lithium heparin) were collected from patients presenting with symptoms suggestive of acute coronary syndromes (ACS) for correlation studies as well as from 162 healthy subjects for reference interval determination. Three different hospitals participated in a patient specimen and analytical validation study (n=186) for the i-STAT cTnI assay carried out in real time. This study determines the analytical characteristics of the i-STAT cardiac troponin I assay (cTnI i-STAT, Princeton, NJ), a 10-min POC assay, designed to be performed at the bedside.
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