Key result
A target aPTT ratio between 2.0 and 3.5 was necessary to achieve therapeutic anti-factor Xa heparin levels, whereas the commonly recommended ratio of 1.5 resulted in subtherapeutic levels.
Why the study?
What aPTT ratio corresponds to therapeutic anti-factor Xa heparin levels for various reagent-coagulometer combinations in patients receiving unfractionated heparin?
Observational (n=126)
What aPTT ratio corresponds to therapeutic anti-factor Xa heparin levels for various reagent-coagulometer combinations in patients receiving unfractionated heparin?
The commonly recommended aPTT ratio of 1.5 to 2.5 for unfractionated heparin monitoring may result in subtherapeutic anti-factor Xa levels, suggesting a target ratio of 2.0 to 3.5 may be more appropriate for less responsive reagents.
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Lab-specific aPTT calibration to anti-Xa levels is supported; challenges universal 1.5-2.5 ratio.
Bates et al. (2001) conducted an observational in Patients receiving unfractionated heparin (n=126). aPTT ratio was evaluated on aPTT results corresponding to therapeutic anti-factor Xa heparin levels. A target aPTT ratio between 2.0 and 3.5 was necessary to achieve therapeutic anti-factor Xa heparin levels, whereas the commonly recommended ratio of 1.5 resulted in subtherapeutic levels.
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