Evaluation of the analytical and clinical performance of a high-sensitivity troponin I point-of-care assay in the Mersey Acute Coronary Syndrome Rule Out Study (MACROS-2).

Objectives: The objective of this study is to evaluate the analytical and diagnostic performance of a high-sensitivity point-of-care (POC) cardiac troponin I assay, the Quidel TriageTrue™ (QuidelOrtho Inc, San Diego, USA), compared to central laboratory testing (CLT) in accelerated diagnostic protocols (ADP) in real time in a clinical environment.

Methods: In a nested sub-study of a pragmatic randomised control trial, consecutive patients with suspected acute coronary syndrome (ACS) and chest pain <12 h duration were randomised to the ESC 0/1 and 0/3-h ADP. Subjects underwent sampling for Quidel TriageTrue POC hs-TnI whole blood and plasma, CLT hs-TnT Roche Elecsys and a validated, NICE approved CLT High sensitivity cardiac troponin I (hs-TnI) (Siemens Attellica) at each time point. Assay imprecision was assessed by repeat analysis of whole blood samples at three levels (low, near 10 % CV 5-10 ng/L, medium, approximating 99th percentile 15-25 ng/L and high, 3-5 times the 99th percentile, 60-100 ng/L). Final diagnosis was adjudicated at 6 weeks by Roche hs-TnT using the 4th universal definition of myocardial infarction (MI).

Results: A total of 1,157 patients consented and had both investigational POC whole blood and plasma and central lab hs-cTn available. The median age was 59, 47.2 % were female and 15 % had suffered a previous MI. Assay imprecision of whole blood POC TriageTrue revealed 10 % CV at 8.6 ng/L (>50 % lower than 99th percentile [20.5 ng/L]) and a 20 % CV at 1.2 ng/L. Receiver operator characteristics (ROC) curves were computed for each assay against adjudicated index type 1 MI to study clinical performance. At all-time points there were excellent performance for whole blood POC TriageTrue: area under the curve (AUC) 0.97 [95 % CI 0.94-098], 0.98 [95 % CI 0.97-1.00] and 0.95 [95 % CI 0.92-0.98] at time 0, 1 and 3 h respectively. There was statistical equivalence for performance of whole blood and plasma POC TriageTrue hs-TnI and laboratory Siemens Atellica hs-TnI.

Conclusions: The whole blood POC TriageTrue hs-TnI assay demonstrates imprecision levels consistent with high sensitivity characteristics and has a clinical performance equivalent to an established, validated and NICE approved laboratory Siemens Atellica hs-TnI.