BACKGROUND: Both the activated partial thromboplastin time (aPTT) and anti-Xa assay can be used to monitor unfractionated heparin (UFH). Following implementation of an anti-Xa method for heparin dosing protocols in our hospital, we became aware of many patients with discordant aPTT and anti-Xa values. OBJECTIVE: To determine the frequency of discordant aPTT and anti-Xa values in a large cohort of hospitalized patients treated with UFH, as well as the demographics, coagulation status, indication for UFH, and clinical outcomes in this population. METHODS: All aPTT and anti-Xa values from adults hospitalized between February and August 2009 at Stanford Hospital who were treated with UFH were analyzed. All samples were drawn simultaneously. A polynomial fit correlating aPTT and anti-Xa with a 99% confidence limit was designed. Paired aPTT/anti-Xa values were grouped according to whether the paired values fell within or outside of the concordant area. Patients were placed into groups based on concordance status, and clinical outcomes were assessed. RESULTS: A total of 2321 paired values from 539 patients were studied; 42% of data pairs had a high aPTT value relative to the anti-Xa value. Patients with elevated baseline prothrombin time/international normalized ratio or aPTT frequently demonstrated disproportionate relative prolongation of the aPTT. Patients with at least 2 consecutive high aPTT to anti-Xa values had increased 21-day major bleeding (9% vs 3%; p = 0.0316) and 30-day mortality (14% dead vs 5% dead at 30 days; p = 0.0202) compared with patients with consistently concordant values. CONCLUSIONS: aPTT and anti-Xa values are frequently discordant when used to measure UFH in hospitalized patients. A disproportionate prolongation of the aPTT relative to the anti-Xa was the most common discordant pattern in our study. Patients with relatively high aPTT to anti-Xa values appear to be at increased risk of adverse outcomes. Monitoring both aPTT and Xa values may have utility in managing such patients.
BACKGROUND: Both the activated partial thromboplastin time (aPTT) and anti-Xa assay can be used to monitor unfractionated heparin (UFH). Following implementation of an anti-Xa method for heparin dosing protocols in our hospital, we became aware of many patients with discordant aPTT and anti-Xa values. OBJECTIVE: To determine the frequency of discordant aPTT and anti-Xa values in a large cohort of hospitalized patients treated with UFH, as well as the demographics, coagulation status, indication for UFH, and clinical outcomes in this population. METHODS: All aPTT and anti-Xa values from adults hospitalized between February and August 2009 at Stanford Hospital who were treated with UFH were analyzed. All samples were drawn simultaneously. A polynomial fit correlating aPTT and anti-Xa with a 99% confidence limit was designed. Paired aPTT/anti-Xa values were grouped according to whether the paired values fell within or outside of the concordant area. Patients were placed into groups based on concordance status, and clinical outcomes were assessed. RESULTS: A total of 2321 paired values from 539 patients were studied; 42% of data pairs had a high aPTT value relative to the anti-Xa value. Patients with elevated baseline prothrombin time/international normalized ratio or aPTT frequently demonstrated disproportionate relative prolongation of the aPTT. Patients with at least 2 consecutive high aPTT to anti-Xa values had increased 21-day major bleeding (9% vs 3%; p = 0.0316) and 30-day mortality (14% dead vs 5% dead at 30 days; p = 0.0202) compared with patients with consistently concordant values. CONCLUSIONS: aPTT and anti-Xa values are frequently discordant when used to measure UFH in hospitalized patients. A disproportionate prolongation of the aPTT relative to the anti-Xa was the most common discordant pattern in our study. Patients with relatively high aPTT to anti-Xa values appear to be at increased risk of adverse outcomes. Monitoring both aPTT and Xa values may have utility in managing such patients.
Authors: Jacob T Beyer; Stuart E Lind; Sheila Fisher; Toby C Trujillo; Michael F Wempe; Tyree H Kiser Journal: J Thromb Thrombolysis Date: 2020-02 Impact factor: 2.300
Authors: Manuel Isherwood; Michelle L Murphy; Angela L Bingham; Laura A Siemianowski; Krystal Hunter; James M Hollands Journal: J Thromb Thrombolysis Date: 2017-05 Impact factor: 2.300
Authors: David C Chu; Abdel Ghanie Abu-Samra; Grayson L Baird; Cynthia Devers; Joseph Sweeney; Mitchell M Levy; Christopher S Muratore; Corey E Ventetuolo Journal: Intensive Care Med Date: 2014-12-03 Impact factor: 17.440
Authors: Tanya Williams-Norwood; Megan Caswell; Barbara Milner; Joseph C Vescera; Kelly Prymicz; Amy G Ciszak; Carol Ingle; Christopher Lacey; Evi X Stavrou Journal: AACN Adv Crit Care Date: 2020-06-15
Authors: Jori E May; Rance Chad Siniard; Laura J Taylor; Marisa B Marques; Radhika Gangaraju Journal: Am J Clin Pathol Date: 2022-03-03 Impact factor: 5.400
Authors: Maureen A Smythe; Jennifer Priziola; Paul P Dobesh; Diane Wirth; Adam Cuker; Ann K Wittkowsky Journal: J Thromb Thrombolysis Date: 2016-01 Impact factor: 2.300
Authors: Anna N Balandina; Ilya I Serebriyskiy; Alexander V Poletaev; Dmitry M Polokhov; Marina A Gracheva; Ekaterina M Koltsova; David M Vardanyan; Irina A Taranenko; Alexey Yu Krylov; Evdokiya S Urnova; Kirill V Lobastov; Artem V Chernyakov; Elena M Shulutko; Andrey P Momot; Alexander M Shulutko; Fazoil I Ataullakhanov Journal: PLoS One Date: 2018-06-28 Impact factor: 3.240
Authors: Emily Whitman-Purves; James C Coons; Taylor Miller; Jeannine V DiNella; Andrew Althouse; Mark Schmidhofer; Roy E Smith Journal: Clin Appl Thromb Hemost Date: 2017-12-06 Impact factor: 2.389