Table 2.

Paired Measurements of the Activated Partial Thromboplastin Time and Antifactor Xa Assay (n = 342)

Anti-Xa, U/mL	aPTT, s
	<71	71-105	>105
<0.3	104a	33b	2b
0.3-0.7	60c	78a	30b
>0.7	4c	10c	21a

Anti-Xa, antifactory Xa; aPTT, activated partial thromboplastin time; UFH, unfractionated heparin.

^aConcordance between anti-Xa and aPTT.

^bDiscordance between anti-Xa and aPTT, potential for UFH underdosing.

^cDiscordance between anti-Xa and aPTT, potential for UFH overdosing.