The novel hs-POC-cTnI assay showed comparable accuracy and cTnI concentrations across venous whole blood, plasma, and capillary blood with inter-sample CVs ≤6.9%.
Does a novel hs-POC-cTnI assay provide accurate and comparable troponin I concentrations across venous whole blood, venous plasma, and capillary blood when performed by nurses?
A novel point-of-care high-sensitivity cardiac troponin I assay demonstrates excellent accuracy and comparable results across venous whole blood, venous plasma, and capillary blood when performed by nurses.
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Abstract Background High-sensitivity (hs) cardiac troponin measurements are widely used to assess chest pain patients in the Emergency Department. Point-of-care hs-cardiac troponin measurements may decrease time to decision-making but will require testing and validation prior to clinical implementation. Objective To evaluate accuracy and troponin I concentrations across different sample types; venous whole blood, venous plasma, and capillary blood (finger prick), with analysis performed by healthcare professionals using a novel point-of-care cardiac hs-troponin I (hs-POC-cTnI) assay. Methods We performed the study according to the in vitro diagnostic medical devices regulation (IVDR) EU 2017/746 and ISO 20916:2019. We recruited 170 participants with cTnI concentrations distributed across the measuring range of the hs-POC-cTnI assay for Li-heparin whole blood (1.4-9000 ng/L), including 34 participants with cTnI concentrations 30 ng/L. The preliminary reported 99-percentile in healthy subjects is 32 ng/L for this hs-POC-cTnI assay. We collected one 4 mL venous Li-heparin sample and performed one finger prick blood draw from all participants. The Li-heparin sample was used to run 2 replicates of whole blood (WB) and 2 replicates of fresh plasma (P). We collected and analysed two samples of capillary blood (F) from the same finger prick blood draw. Handling and processing of samples, and all analyses were performed by nurses. Comparison of repeatability was calculated as mean of the squared coefficient of variation (CV)% over duplicate measurements for all samples. We compared cTnI concentrations between all three sample types and bias was evaluated using Bland Altman difference plots and weighted Deming regression. Results The mean CV for duplicate results in individual patients was 5.1% for whole blood, 5.4% for fresh plasma and 6.9% for capillary blood. In subjects with cTnI concentrations 30 ng/L, the absolute difference for cTnI concentrations was 0.4 (95% CI 0.0 to 0.8) ng/L between plasma and whole blood, 0.5 (-0.2 to 1.1) ng/L between capillary blood and whole blood, and 0.1 (-0.7 to 0.8) ng/L between capillary blood and plasma. Bland-Altman plots did not demonstrate systematic differences in cTnI concentrations between sample types, as evaluated by percent difference across the measuring range of the hs-POC-cTnI assay (Fig 1) and absolute difference in ng/L for samples with cTnI concentration 30 ng/L (Fig. 2). Weighted Deming regression analysis did not demonstrate clinically significant bias across sample types for the hs-POC-cTnI assay. Conclusion We demonstrate excellent accuracy, also in the low range, across sample types for the hs-POC-cTnI assay, with all handling and analysis being performed by nurses. Absolute cTnI concentrations did not differ significantly between sample types, which supports that cTnI quantification with the novel hs-POC-cTnI assay may be performed in venous whole blood, venous plasma, and capillary blood.Figure 1:Whole measuring range Figure 2:Samples 30 ng/L
Gjorven et al. (Sat,) reported a other. The novel hs-POC-cTnI assay showed comparable accuracy and cTnI concentrations across venous whole blood, plasma, and capillary blood with inter-sample CVs ≤6.9%.