Association of Anti-factor Xa Activity With Venous Thromboembolism in Critically Ill Patients (AntiXa-ICU)

September 23, 2025 updated by: Eva Schaden, Medical University of Vienna

Association of Anti-factor Xa Activity With Venous Thromboembolism in Critically Ill Patients: a Prospective Multicentre Cohort Study

The goal of this observational study is to analyse the association between anti-factor Xa activity (antiXa) and the occurence of venous thromboembolism (VTE; either deep vein thrombosis and/or pulmonary embolism) in critically ill patients who are admitted to an intensive care unit. The main questions it aims to answer are:

  • What is the association between antiXa and VTE?
  • What is the association between antiXa and symptomatic, respectively incidental, VTE?
  • How is pharmacological anticoagulation with enoxaparin related to measured antiXa?
  • What is the association between antiXa and bleeding complications.
  • What is the incidence of venous thromboembolism in patients treated at an intensive care unit?
  • How is the occurence of VTE related to patient-centred outcomes such as mortality, quality of life, length of stay and days outside of the intensive care unit/hospital.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
1300

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Austria
      • Vienna, Austria, 1090
        • Recruiting
        • Department of Anaesthesia, Intensive Care Medicine and Pain Medicine, Medical University of Vienna
        • Contact:
          • Christoph Dibiasi, MD
    • Styria
      • Graz, Styria, Austria, 8063
        • Recruiting
        • Department of Internal Medicine, Medical University of Graz
        • Contact:
          • Philipp Eller, Prof.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Adult patients admitted to an surgical or medical intensive care unit who do not receive therapeutic anticoagulation

Description

Inclusion Criteria:

  • Age over 18 years at the time of intensive care unit admission
  • Admission to a participating intensive care unit within the last 24 hours
  • Expected discharge is later than 48 hours after enrolment

Exclusion Criteria:

  • Therapeutic anticoagulation, defined as enoxaparin dose of at least 100 IE/kg when given twice daily or of at least 150 IE/kg when given once daily
  • Extracorporeal membrane oxygenation in place or planned within 48 hours of study enrolment
  • Planned regular administration of vitamin K antagonists, unfractionated heparin, low molecular weight heparin other than enoxaparin, thrombin inhibitors or factor X inhibitors within the observation period
  • Estimated life expectancy below 48 hours or comfort terminal care order in place
  • Previously diagnosed heparin-induced thrombocytopenia
  • Pre-operative admission for elective surgery
  • Previous enrolment in the study

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Intensive care unit patients
Patients who are admitted to an participating intensive care unit who do not receive therapeutic anticoagulation.
Diagnostic test: Anti-factor Xa activity calibrated for enoxaparin
Anti-factor Xa activity calibrated for enoxaparin

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of patients with new-onset venous thromboembolism
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
New-onset deep vein thrombosis and/or new-onset pulmonary embolism. Both symptomatic and incidental events are included.
until discharge from the intensive care unit or up to 14 days after study inclusion

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Number of patients with new-onset upper extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset lower extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset central vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset symptomatic upper extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset symptomatic lower extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset incidental upper extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset incidental lower extremity deep vein thrombosis
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset pulmonary embolism
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset symptomatic pulmonary embolism
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset incidental pulmonary embolism
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with venous thromboembolism
Time Frame: prevalent at study enrolment
prevalent at study enrolment
Number of patients with deep vein thrombosis
Time Frame: prevalent at study enrolment
prevalent at study enrolment
Number of patients with pulmonary embolism
Time Frame: prevalent at study enrolment
prevalent at study enrolment
Number of patients with new-onset venous thromboembolism
Time Frame: 90 days after study enrolment
90 days after study enrolment
Number of days with any bleeding
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of days with major and/or fatal bleeding
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of red blood cell concentrates administered
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Number of days on which either procoagulant medication, platelet transfusion or fresh frozen plasma was administered
Time Frame: until discharge from the intensive care unit or up to 14 days after study inclusion
until discharge from the intensive care unit or up to 14 days after study inclusion
Length of stay in the intensive care unit
Time Frame: 90 days after study enrolment
90 days after study enrolment
Length of stay in the hospital
Time Frame: 90 days after study enrolment
90 days after study enrolment
Death
Time Frame: 90 days after study enrolment
90 days after study enrolment
Days alive and out of the intensive care unit
Time Frame: 90 days after study enrolment
90 days after study enrolment
Days alive and out of the hospital
Time Frame: 90 days after study enrolment
90 days after study enrolment
European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) index value
Time Frame: 90 days after study enrolment
Minimum -1.0, Maximum 1.0; An index value of 1.0 indicates the best possible state of health. Index values below 0.0 indicate the worst possible state of health.
90 days after study enrolment
European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) visual analogue scale
Time Frame: 90 days after study enrolment
Minimum 0. Maximum 100. A value of 0 indicates the worst possible state of health while a value of 100 indicates the best possible state of health.
90 days after study enrolment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Medical University of Vienna

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Eva Schaden, MD, Medical University of Vienna

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 4, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 19, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 4, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 10, 2024

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 29, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 23, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • AntiXa-ICU 1881/2023

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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