What does this research mean for the field?

Monitoring of unfractionated heparin (UFH) therapy via the anti-factor Xa method shows moderate variation (10-40%), while the activated partial thromboplastin time (aPTT) method has lower variation (10-25%), confirming expected therapeutic level interpretations. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.SUPPORTS_CONSENSUS.

What question did this study set out to answer?

To evaluate the performance, variability, and interpretive proficiency of activated partial thromboplastin time (aPTT) and anti-factor Xa (anti-Xa) assays used for unfractionated heparin (UFH) monitoring.

January 10, 2026Seminars in Thrombosis and Hemostasis

External Quality Assessment for Unfractionated Heparin Monitoring: An Update from Australasia/Asia-Pacific

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Key result

aPTT monitoring of UFH shows lower variation than anti-Xa testing.

Why the study?

Unfractionated heparin requires precise monitoring via aPTT or anti-Xa assays to avoid thrombotic and bleeding complications, prompting an updated evaluation of regional laboratory performance.

Key Points

To evaluate the performance, variability, and interpretive proficiency of activated partial thromboplastin time (aPTT) and anti-factor Xa (anti-Xa) assays used for unfractionated heparin (UFH) monitoring.
Analyzed proficiency testing data from the Royal College of Pathologists of Australasia Quality Assurance Program over a 5-year period (2020–2024 inclusive), comprising over 110 enrolments.
Assessed four plasma samples containing varying levels of UFH annually using routine laboratory aPTT and chromogenic anti-Xa assays, evaluating duplicate challenges across separate surveys.
Identified coefficient of variation ranges of 10–40% for anti-Xa assays and 10–25% for aPTT assays in samples containing UFH.
Observed higher measured anti-Xa activity when using anti-Xa reagents containing dextran sulphate compared to reagents formulated without it.
Demonstrated good analytical reproducibility between duplicate survey samples, with participant qualitative interpretations (below, within, or above therapeutic range) generally aligning with true sample heparin content.

Structured PICO

Population

Over 110 enrolments (laboratories) in the Royal College of Pathologists of Australasia Quality Assurance Program, an international external quality assessment (EQA) program for unfractionated heparin monitoring.

Intervention

Unfractionated heparin monitoring using activated partial thromboplastin time (aPTT) or anti-factor Xa (anti-Xa) methods.

Outcome

Reproducibility and coefficient of variation (%) for aPTT and anti-Xa testing.surrogate

External quality assessment of unfractionated heparin monitoring reveals moderate variation for both aPTT and anti-Xa assays, with reagent composition affecting anti-Xa results.

Authors

EFEmmanuel J. FavaloroVascular Medicine SASandya ArunachalamRoyal College of Pathologists of Australasia LPLeonardo PasalicThe University of Sydney

Discussion

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Implication

Moderate variation in UFH monitoring assays warrants interpretive caution; leaves open need for standardization studies.

Cite This Study

Favaloro et al. (2025) studied this question. Monitoring of UFH therapy via anti-Xa method showed moderate variation (10-40%) while aPTT had lower variation (10-25%), confirming expected therapeutic level interpretations.

synapsesocial.com/papers/6963222a91e05aa366cb8b58 https://doi.org/10.1055/a-2779-0035

Topics

HFrEF treatment Heart failure hospitalization Heart failure

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External Quality Assessment for Unfractionated Heparin Monitoring: An Update from Australasia/Asia-Pacific

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

External Quality Assessment for Unfractionated Heparin Monitoring: An Update from Australasia/Asia-Pacific

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

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