Key result
Anti-Xa and APTT measurements were concordant in only 54% of samples from patients on unfractionated heparin, with discordance driven by factor II and VIII activity.
Why the study?
What is the concordance between anti-Xa and APTT for monitoring unfractionated heparin therapy, and what factors contribute to discordance?
Observational (n=149)
What is the concordance between anti-Xa and APTT for monitoring unfractionated heparin therapy, and what factors contribute to discordance?
APTT and anti-Xa assays are frequently discordant during UFH monitoring, partly due to variations in factor II and VIII activity, suggesting ETP may be a useful adjunctive measure.
Answers are grounded in this paper and cite their sources.
Discordance between anti-Xa and APTT in UFH monitoring warrants assay-specific caution; leaves open optimal method for guiding therapy.
We examined the concordance of heparin levels measured by a chromogenic anti-Xa assay and the activated partial thromboplastin time (APTT) during unfractionated heparin therapy (UFH) and the biochemical basis for differences between these measures. We also investigated the endogenous thrombin potential (ETP) as a possible measure of anticoagulation. Paired measures of anti-Xa and APTT were performed on 569 samples from 149 patients on UFH. The anti-Xa values and the APTT were concordant in only 54% of measurements. One hundred twelve samples from 59 patients on UFH were assayed for APTT, anti-Xa, factor II, factor VIII, and ETP. Supratherapeutic APTT values but therapeutic anti-Xa results had decreased factor II activity. Subtherapeutic APTT but therapeutic anti-Xa values had high factor VIII activity. ETP correlated with anticoagulation status and UFH dose. In conclusion, factor II and VIII activity contributes to discordance between APTT and anti-Xa results. ETP measurements may provide an additional assessment of anticoagulation status.
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Takemoto et al. (2013) conducted an observational in Patients on unfractionated heparin therapy (n=149). Anti-Xa and APTT measurements was evaluated on Concordance of heparin levels measured by anti-Xa assay and APTT. Anti-Xa and APTT measurements were concordant in only 54% of samples from patients on unfractionated heparin, with discordance driven by factor II and VIII activity.
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