Abstract Number: PB0545
Meeting: ISTH 2020 Congress
Background: Preanalytical procedures impact the accuracy of coagulation assay results and thus patient diagnosis and monitoring of anticoagulant therapy. Sample stability under different storage conditions is a key parameter and specific temperature and time criteria need to be defined for individual assays.
Aims: To evaluate the influence of plasma storage conditions on test results using routine coagulation assays on the fully automated cobas t 711 analyser (Roche Diagnostics).
Methods: Experiments were performed at a routine laboratory in Germany using anonymised residual platelet-poor-plasma samples. Eligible samples had to be processed within 2 hours of collection and were selected based on initial measurements using the laboratory’s routine assay. Fresh samples were tested in triplicate at time zero (t0) and measurements repeated after storage at predefined conditions. Test storage temperatures/durations, concentration groups (covering the relevant measuring range) and acceptance criteria (% deviation of mean/median measurements from t0) for each assay are summarised in Table 1. Tina-quant® D-Dimer Gen 2 (DD2), Prothrombin Time (PT Rec), Thrombin Time (TT), activated partial thromboplastin time (aPTT) and fibrinogen (FIB) assays (Roche Diagnostics) were evaluated.
Results: Ranges of mean deviation from t0 are summarised by assay and storage condition in Table 1. Sample stability criteria were defined as follows: DD2 assay, 8 hours at 18-25°C, 4 days at 2-8°C and 28 days at -20°C, one freeze-thaw cycle; PT Rec assay, 12 hours at 18-25°C; TT assay, 4 hours at 18-25°C (2 hours in samples from heparin-treated patients), no storage at -20°C or freeze/thaw cycles; aPTT assay, 2 hours at 18-25°C; FIB assay, 4 hours at 18-25°C.
Conclusions: Sample stability criteria are demonstrated for the DD2, PT Rec, TT, aPTT, and FIB assays on the cobas t 711 analyser, for application in routine laboratory practice.
| Assay | Storage temperature | Time points | Concentration range | Acceptance criteria | Mean deviation from t0, % |
| DD2 | 18-25°C | 0, 6, 8, 12-18 hrs | 0.2-9 µg FEU/mL | 0.2-0.5 µg FEU/mL: ±0.05 µg FEU/mL; >0.5 µg FEU/mL: ±10%* | -2.7 to 0.9 |
| 2-8°C | 0, 6, 12, 24 hrs, 2, 4, 5 days | -6.3 to 0.9 | |||
| -20°C; freeze/thaw | 0, 1, 2, 4, 5 wks; 2x 48 hrs | -6.5 to 1.3; -4.8 to -2.2 | |||
| PT Rec | 18-25°C | 0, 10, 12, 13, 16, 17 hrs | 0.8-5 INR | ±10% | -4.5 to 10.6 |
| TT | 18-25°C | 0, 1, 2, 4, 5 hrs | 14-120 secs | ±10%; ±20% for heparin samples | -18.7 to 1.5 |
| -20°C; freeze/thaw | 0, 3, 7, 14, 21, 28 days, 6, 8 wks; 3x 48 hrs | -32.5 to 1.6; -48.8 to 3.3 | |||
| aPTT | 18-25°C | 0, 1, 2, 4, 5 hrs | 25-160 secs | <100 secs: ±10%; >100 secs: ±20% | -0.5 to 16.6 |
| FIB | 18-25°C | 0, 1, 2, 4, 5 hrs | 60-900 mg/dL | ±10% | -1.7 to 3.0 |
| *Results for high concentration (>0.5 µg FEU/mL) samples presented. FEU, fibrinogen equivalent unit | |||||
[Table 1. Storage conditions tested, acceptance criteria and results (all time points and concentrations).]
To cite this abstract in AMA style:
Hoffmann M, Gottschalk N, Huber P, von Allmen-Zürcher N. Sample Stability for a Broad Panel of Coagulation Assays on the Cobas t 711 Analyser Using Plasma Stored under Different Conditions [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/sample-stability-for-a-broad-panel-of-coagulation-assays-on-the-cobas-t-711-analyser-using-plasma-stored-under-different-conditions/. Accessed September 22, 2023.« Back to ISTH 2020 Congress
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