Point-of-care testing (POCT) cardiac troponin (cTn) measurements are being used increasingly, despite the fact that evidence on the safety of their use is outdated, not taking into account current ‘gold standard’ high-sensitivity cardiac troponin (hs-cTn) assays. In the present study, we aimed to compare the analytical and diagnostic performance of the AQT90-flex POCT cTnT assay (which is the POCT assay with the lowest reported 99th percentile cutoff currently available) with the laboratory-based Roche Modular E170 hs-cTnT assay.
Materials and methods
During a 4-month prospective observational cohort study, laboratory-based hs-cTnT and POCT cTn were measured simultaneously in 261 undifferentiated chest-pain patients presenting to the emergency department (ED) of the Medical Centre Leeuwarden to determine the diagnostic accuracy of both assays in predicting acute myocardial infarction (AMI) at presentation.
The POCT cTn assay had a lower sensitivity [68 (49–82) vs. 91 (75–98)] and a lower negative predictive value [95 (91–97) vs. 98 (95–100)%] for the prediction of AMI at presentation compared with the hs-cTnT assay. Furthermore, in three patients, the POCT cTnT assay yielded unexpectedly high results, whereas hs-cTnT results were negative. None of these patients had an AMI, and no possible explanation could be found.
The AQT90-flex POCT cTnT assay is not yet sensitive and reliable enough to be used to exclude AMI in the ED with a single blood draw at the time of presentation in the ED, and therefore, may have limited applicability in the ED setting.