Point-of-care high-sensitivity troponin testing for rapid chest pain triage in emergency primary care: preliminary efficacy findings from the OUT-POC Study
T R Johannessen, D Atar, S Halvorsen, J Munkhaugen, O M Vallersnes, A Bakken, A C K LarstorpAbstract
Background
High-sensitivity troponin testing at the point-of-care (POC) level may enable faster and more accurate assessment of chest pain in low-resource, out-of-hospital settings. The ongoing prospective OUT-POC study (One-hoUr Troponin using a high-sensitivity Point-Of-Care assay in emergency primary care), initiated in June 2025, aims to enrol 2,500 patients across six emergency primary care clinics in Norway.
Purpose
This interim analysis evaluates the triage efficacy of the study`s POC assay (TRIAGETRUE High Sensitivity Troponin I (hs-cTnI) Test) using the ESC 0/1-hour algorithm, comparing it to the standard-of-care central laboratory assay (Elecsys 5th-generation hs-cTnT) to identify discrepancies and assess potential safety concerns for patients classified as rule-out by the POC assay.
Methods
A prespecified interim analysis was performed on the first 300 participants enrolled at the largest study site. EDTA whole blood was collected for the POC assay, and lithium heparin samples were sent to the central laboratory via pneumatic tube for hs-cTnT analysis. The hs-cTnT results were blinded to the treating physicians. Major discrepancies were defined as cases in which the POC assay triaged a patient for direct rule-out, while the central laboratory assay classified the same patient as rule-in.
Results
During the first three months of inclusion, data were analysed from 308 patients with a median age of 55 years (IQR 42–69) and 47.4% (N=146) female. The POC assay triaged 65.6% (n=202) to 0-hour rule-out (<4 ng/L and ≥3 hours since symptom onset), compared with 45.5% (n=140) triaged by the hs-cTnT assay (<5 ng/L and ≥3 hours since symptom onset). The 0-hour rule-in rates were 4.2% for the POC assay (≥60 ng/L) and 2.6% for the hs-cTnT assay (≥52 ng/L). The POC assay also triaged 90 patients (29.2%) to the indeterminate observation group, requiring a repeat 1-hour sample. In comparison, the hs-cTnT assay would have required repeat sampling in 160 patients (51.9%), though 70 of these were not obtained due to blinded results. After the repeat sample, the POC 0/1-hour algorithm triaged 74.0% of the patients as rule-out, suggesting potential eligibility for discharge. No major discrepancies between the two assays were identified after a single sample. Technical error codes occurred in 3 of 308 patients (1.0%) during POC testing.
Conclusions
Compared with the standard-of-care central laboratory hs-cTnT assay, the TRIAGETRUE hs-cTnI POC assay provides a higher single-sample rule-out rate and a shorter turnaround time. Together, these features enable faster identification of rule-out patients and may improve patient flow and chest pain management in busy clinics. No safety concerns have been identified for the point-of-care assay, supporting continuation of the larger implementation study.Triage Efficacy after a single blood sample