Inpatient Monitoring of Unfractionated Heparin

NCT ID: NCT06329921

Last Updated: 2025-12-12

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

ENROLLING_BY_INVITATION

Clinical Phase

NA

Total Enrollment

2000 participants

Study Classification

INTERVENTIONAL

Study Start Date

2024-06-26

Study Completion Date

2026-07-31

Brief Summary

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Unfractionated heparin (UFH) is the most widely used intravenous (IV) anticoagulant for treating and preventing thromboembolic disease (e.g., blood clots ). UFH must be closely monitored and adjusted in the hospital. There are two assays used to monitor UFH: 1) the activated partial thromboplastin time (PTT) and 2) the chromogenic anti-factor Xa assay (anti-Xa). This study aims to compare PTT and anti-Xa methods for monitoring UFH in a pragmatic, randomized controlled trial to determine which helps patients reach a therapeutic anticoagulation range faster.

Detailed Description

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Unfractionated heparin (UFH) is the most widely used intravenous (IV) anticoagulant for the treatment and prevention of thromboembolic disease (e.g., blood clots ). When administered by intravenous injection, the onset of action is immediate. Indications for use of UFH include venous thromboembolism, acute coronary syndrome, and acute ischemic stroke. UFH is used to prevent thrombosis in the setting of arrhythmias, extracorporeal membrane oxygenation (ECMO), cardiopulmonary bypass (CPB), and endovascular procedures. The unpredictable pharmacokinetics of UFH and interpatient variability result in a narrow therapeutic index restricting its use to the hospital setting with close monitoring and adjustments.

Two validated assays exist and are in use at the VUMC adult hospital for the monitoring of unfractionated heparin: 1) the activated partial thromboplastin time (PTT) and 2) the chromogenic anti-factor Xa assay (anti-Xa). At VUMC, the PTT protocol is managed by nursing; the anti-Xa protocol is managed by clinical pharmacy. Both are clinically acceptable methods for titration and adjustment of unfractionated heparin. Assessing the therapeutic effect of unfractionated heparin is most often performed with the PTT, which requires institutional calibration to a specific heparin level to account for the variable PTT responses with different commercial reagents and laboratory instruments. The PTT can be influenced by various elements during sample processing, laboratory analysis, and patient biological factors that may cause it to be an inaccurate indication of the degree of anticoagulation. This can lead to patients not getting the correct heparin dosing for their clinical needs.

The anti-Xa assay is another method of measuring the degree of therapeutic effect of heparin. In routine clinical practice the anti-Xa is not as widely available and less familiar among many providers. This assay can be impacted by variability in sample collection and processing and laboratory analysis. Compared to the PTT assay, however, it is much less influenced by patient-specific biological factors. This may help improve heparin monitoring and titration to ensure patients receive therapeutic levels of anticoagulation and do not get too much or too little heparin. However, large studies using anti-Xa for management of heparin in the treatment of venous thromboembolism have not been performed.

PTT and anti-Xa heparin monitoring protocols have not been compared in a prospective, randomized setting. The study team will conduct a pragmatic, randomized clinical trial comparing the effectiveness of both methods for optimal monitoring of intravenous unfractionated heparin for systemic anticoagulation in hospitalized adult patients.

Conditions

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Blood Clot Thrombosis

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

This study will be performed as a pragmatic, randomized controlled clinical trial with parallel group assignment.
Primary Study Purpose

HEALTH_SERVICES_RESEARCH

Blinding Strategy

NONE

Study Groups

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Active Comparator: PTT protocol

Patients randomized to this arm will be monitored using the nurse-managed PTT guided protocol. This includes patients on both high- and low-dose heparin protocols.

Group Type ACTIVE_COMPARATOR

PTT protocol

Intervention Type OTHER

Patients will be monitored using the nurse-managed PTT protocol.

Active Comparator: anti-Xa protocol

Patients randomized to this arm will be monitored using the pharmacy-managed anti-Xa protocol. This includes patients on both high- and low-dose heparin protocols.

Group Type ACTIVE_COMPARATOR

anti-Xa protocol

Intervention Type OTHER

Patients will be monitored using the pharmacy-managed anti-Xa protocol.

Interventions

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PTT protocol

Patients will be monitored using the nurse-managed PTT protocol.

Intervention Type OTHER

anti-Xa protocol

Patients will be monitored using the pharmacy-managed anti-Xa protocol.

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Patients at Vanderbilt University Hospital age 18 years and older who are admitted as observation or inpatients for whom intravenous unfractionated heparin (monitored via the PTT nurse-managed protocol) is ordered.
* Baseline PTT value is ≥0 and ≤ 36.0 seconds
* Baseline heparin level anti-Xa assay value is ≥0 and ≤0.3

Exclusion Criteria

* Indication for anticoagulation is extracorporeal membrane oxygenation or cerebrovascular ischemic event.
* Provider determines patient is not appropriate for the study.
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Vanderbilt University Medical Center

OTHER

Sponsor Role lead

Responsible Party

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Benjamin Tillman

Assistant Professor

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Benjamin Tillman, MD

Role: PRINCIPAL_INVESTIGATOR

Vanderbilt University Medical Center

Locations

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Vanderbilt University Medical Center

Nashville, Tennessee, United States

Site Status

Countries

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United States

References

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Hirsh J, Warkentin TE, Raschke R, Granger C, Ohman EM, Dalen JE. Heparin and low-molecular-weight heparin: mechanisms of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest. 1998 Nov;114(5 Suppl):489S-510S. doi: 10.1378/chest.114.5_supplement.489s. No abstract available.

Reference Type BACKGROUND
PMID: 9822059 (View on PubMed)

Smythe MA, Priziola J, Dobesh PP, Wirth D, Cuker A, Wittkowsky AK. Guidance for the practical management of the heparin anticoagulants in the treatment of venous thromboembolism. J Thromb Thrombolysis. 2016 Jan;41(1):165-86. doi: 10.1007/s11239-015-1315-2.

Reference Type BACKGROUND
PMID: 26780745 (View on PubMed)

Eikelboom JW, Hirsh J. Monitoring unfractionated heparin with the aPTT: time for a fresh look. Thromb Haemost. 2006 Nov;96(5):547-52.

Reference Type BACKGROUND
PMID: 17080209 (View on PubMed)

Olson JD, Arkin CF, Brandt JT, Cunningham MT, Giles A, Koepke JA, Witte DL. College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: laboratory monitoring of unfractionated heparin therapy. Arch Pathol Lab Med. 1998 Sep;122(9):782-98.

Reference Type BACKGROUND
PMID: 9740136 (View on PubMed)

Wool GD, Lu CM; Education Committee of the Academy of Clinical Laboratory Physicians and Scientists. Pathology consultation on anticoagulation monitoring: factor X-related assays. Am J Clin Pathol. 2013 Nov;140(5):623-34. doi: 10.1309/AJCPR3JTOK7NKDBJ.

Reference Type BACKGROUND
PMID: 24124140 (View on PubMed)

Marlar RA, Clement B, Gausman J. Activated Partial Thromboplastin Time Monitoring of Unfractionated Heparin Therapy: Issues and Recommendations. Semin Thromb Hemost. 2017 Apr;43(3):253-260. doi: 10.1055/s-0036-1581128. Epub 2016 Jun 6.

Reference Type BACKGROUND
PMID: 27272964 (View on PubMed)

Provided Documents

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Document Type: Statistical Analysis Plan

View Document

Other Identifiers

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232192

Identifier Type: -

Identifier Source: org_study_id

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