Method comparison of light transmission platelet aggregometry on Thrombomate XRA and PAP-8E within a routine patient cohort

Introduction: Light transmission aggregometry (LTA) is well-established in platelet function analysis (Gresele 2015; AWMF 2018) and can be used for monitoring of platelet inhibitor therapy (Nakahara et al. 2022). The laborious manual sample preparation process however is susceptible to handling errors, which has led to the development of automated aggregometers with high potential for increased standardization. The Thrombomate XRA (Behnk Elektronik, Germany) is a recently introduced aggregometer with a relatively high degree of automation. In this study, we compared the Thrombomate XRA to the Platelet aggregation Profiler-8E (PAP-8, mölab, Germany), a well-established manual aggregometer.

Method: We included 63 patients from clinical routine, which were either screened for platelet function disorders or underwent monitoring of platelet inhibitor therapy. LTA was performed on PAP-8 and Thrombomate for each patient, using citrated platelet-rich plasma. Inductors used for the PAP-8 were arachidonic acid (ARA, 1mM), ADP low (5 µM), ADP high (20 µM), epinephrine (EPI, 5µM), collagen (COL, 1.9 µg/mL, calf) and ristocetin (RIS, 1.2 mg/mL). Manufacturer: mölab. Inductors used on the Thrombomate were ARA (1mM), ADP low (5 µM), ADP high (10 µM), EPI (5µM), COL (2 µg/mL, horse) and RIS (1.2 mg/mL). Manufacturer: probe&go. Results are reported as maximal aggregation (MA).

Results: Quantitative comparison revealed absolute differences>20% MA in 19 patients for ARA, 23 patients for ADP low, 23 patients for ADP high, 11 patients for COL, 14 patients for EPI, and 7 patient for RIS. Qualitative expert-based interpretation of aggregation curves, based on reference intervals provided by the respective manufacturers, led to differing results in 14 patients for ARA, 20 patients for ADP low, 12 patients for ADP high, 4 patients for COL, 6 patients for EPI, and 1 patient for RIS.

Conclusion: Lacking comparability between LTA platforms is a well-described issue in platelet function analysis (Althaus et al. 2019). Using patient samples from clinical routine, we showed that this issue applies to the comparison of manual and automated aggregometers as well, even though previous reports showed a much more agreeable method comparability in healthy individuals. Discrepant results may be a result of differences in the inductors or variations in the automated or manual workflows, including potential handling errors or pre-analytic influences. The present study represents the first independent method comparison of the Thrombomate aggregometer to date.

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Artikel online veröffentlicht:
13. Februar 2025