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Presentation Details
| Risk Factors for Supratherapeutic aPTTs on Heparin Intravenous Infusion Wade Tung, Katelyn Sylvester, Kaitlin Crowley, Dareen Kanaan. Brigham and Women's Hospital, Boston, MA, USA |
Abstract
Background: Therapeutic anticoagulation is commonly required in hospitalized patients to treat or prevent thromboembolism. Unfractionated heparin (UFH) is frequently selected because of its short half-life, reversibility, and well-established efficacy. At our institution, UFH infusions are ordered as provider-driven fixed dose infusions, or as standardized, nurse-driven nomograms, with or without boluses, that target activated partial thromboplastin time (aPTT) ranges of 60-80 seconds or 50-70 seconds. Despite the use of nomograms and aPTT monitoring strategies, supratherapeutic aPTT levels are not uncommon. Current monitoring strategies are primarily reactive, including daily heparin reports, electronic health record-generated intervention alerts, and Hemostatic and Antithrombotic Stewardship pharmacist oversight. Identifying risk factors associated with supratherapeutic aPTTs may allow proactive, early interventions and more individualized UFH dosing strategies. Objectives: To evaluate patients with aPTT ≥120 seconds within the first 48 hours of UFH administration and identify risk factors for supratherapeutic anticoagulation. Methods: This single-center, retrospective chart review will include adult patients who received UFH infusions in any inpatient area or the emergency department between January and August 2025. Exclusion criteria will be a baseline aPTT >40 seconds or unknown, highest aPTT <50 seconds while receiving UFH infusion, aPTT collected less than 6 hours after UFH initiation, the use of anti-Xa monitoring, or UFH initiation at an outside hospital. Patients will be stratified into two groups according to their highest aPTT in a non-procedural area within 48 hours of UFH initiation: 1) aPTT ≥120 seconds (higher aPTT group) and 2) a comparator group with aPTT between 50 and 119.9 seconds. Collected endpoints will include age, sex, weight, body mass index (BMI), admitting service, concomitant antiplatelet therapy, exposure to another anticoagulant within 48 hours prior to UFH initiation, the components of the Charlson comorbidity score, and the presence of acute kidney injury per KDIGO criteria. Descriptive and inferential statistics will be used to compare groups and explore associations between patient characteristics and supratherapeutic aPTTs. This study has been reviewed and deemed exempt by the Mass General Brigham institutional review board. Preliminary Results: Of the 130 patients screened, 75 met inclusion criteria: 33 in the higher aPTT group and 42 in the comparator group. Median age was 70 years (IQR 58.5-74) in the higher aPTT group and 69 (IQR 57.5-74) in the comparator group. Median BMI was 28.0 kg/m² (IQR 24.9-30.5) in the higher aPTT group and 27.9 kg/m² (IQR 25.2-30.5) in the comparator group, and female patients comprised 57.6% and 35.7% of the groups, respectively. Most patients were admitted to non-surgical services (73.3% vs 26.7%). Concomitant antiplatelet therapy was similar between groups (30.3% vs 29.5%), while more patients in the higher aPTT group received another anticoagulant within 48 hours before UFH initiation (84.8% vs 65.9%). Acute kidney injury was present in 39.0% vs 34.1%. Patient screening is ongoing, with approximately 200 total patients anticipated as the analysis continues. Conclusions: This analysis is currently in progress. The final results will offer insights into patient factors associated with supratherapeutic aPTTs and guide future updates to institutional guidelines to optimize UFH management.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.