Diagnostic performance of a high-sensitive troponin T assay and a troponin T point of care assay in the clinical routine of an Emergency Department: A clinical cohort study.

BACKGROUND

A point of care test (POCT) for troponin T (TnT) in the Emergency Department (ED) was compared to a high-sensitivity TnT (hsTnT) central laboratory test (CLT) to determine the influence of test system and different cut-off values on the diagnostic performance in patients with suspected acute coronary syndrome (ACS) under routine conditions.

METHODS

All patients with routine TnT testing in the ED were enrolled. Only internal medicine patients without STEMI and with both troponin values were analyzed. TnT was measured with a contemporary sensitive POCT assay in the ED and with a hs-assay in the central laboratory. The diagnostic performance was analyzed at two different cut-off points (99th percentile and conventional rule-in cut-offs). Primary endpoint was the diagnosis of NSTEMI.

RESULTS

Of all patients (n=3423), 3.6% had a diagnosis of NSTEMI (n=124). For the hsTnT assay, 28.4% of all values were at or below the lower limit of detection (LOD) as compared to 75.7% of the POC-TnT-values. The area under the receiver operating curves did not differ significantly between the assays (hsTnT: 0.912(95%-CI: 0.884-0.940); POC-TnT: 0.896(95%-CI: 0.859-0.933)). The diagnostic performance was very similar for both assays: the positive predictive value was below 50% for troponin values below 100ng/L and hardly increased for values between 100 and 600ng/L for hs and conventional assays.

CONCLUSIONS

In our cohort of emergency patients, the diagnostic performance of conventional POC-testing was comparable to hsTnT. A 99th percentile cut-off may be useful for rule-out of NSTEMI, but seems limited for routine rule-in strategies.