ThrombosisAntiXa-ICUNCT06357403
Association of Anti-factor Xa Activity With Venous Thromboembolism in Critically Ill Patients
An observational study of Thrombosis and Pulmonary Embolism, run by Medical University of Vienna at 3 sites in Austria.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Thrombosis, Pulmonary Embolism, Enoxaparin
- What is being tested?
- Anti-factor Xa activity calibrated for enoxaparin
- How many people
- 1,300 participants
- Where
- 3 sitesAustria
- Study dates
- 4 May 2024to Aug 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients admitted to an surgical or medical intensive care unit who do not receive therapeutic anticoagulation
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
3 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Austria3 sites, 3 recruiting
- Recruiting
Department of Internal Medicine, Medical University of Graz
Graz, Styria, 8063
Philipp Eller, Prof.
- Recruiting
Division of Intensive Care and Emergency Medicine, Department of Internal Medicine, Medical University Innsbruck
Innsbruck, Tyrol, 6020
Michael Joannidis, Univ. Prof. Dr., 0043 512 9003 0, i-master@i-med.ac.at
- Recruiting
Department of Anaesthesia, Intensive Care Medicine and Pain Medicine, Medical University of Vienna
Vienna, 1090
Christoph Dibiasi, MD
About this study
Official title: 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.
- Conditions
- Thrombosis, Pulmonary Embolism, Enoxaparin
- Being tested
- Anti-factor Xa activity calibrated for enoxaparin
- Medical subject headings
- Thrombosis, Pulmonary Embolism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Anti-factor Xa activity calibrated for enoxaparinDiagnostic test
Anti-factor Xa activity calibrated for enoxaparin
| Study group | Role | What they receive |
|---|---|---|
| Intensive care unit patients | Patients who are admitted to an participating intensive care unit who do not receive therapeutic anticoagulation. Receives: Diagnostic Test: Anti-factor Xa activity calibrated for enoxaparin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of patients with new-onset venous thromboembolism
New-onset deep vein thrombosis and/or new-onset pulmonary embolism. Both symptomatic and incidental events are included.
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Secondary outcomes (25)
Number of patients with new-onset upper extremity deep vein thrombosis
Measured: 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
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset central vein thrombosis
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset pulmonary embolism
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset symptomatic pulmonary embolism
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset incidental pulmonary embolism
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with venous thromboembolism
Measured: prevalent at study enrolment
Number of patients with deep vein thrombosis
Measured: prevalent at study enrolment
Number of patients with pulmonary embolism
Measured: prevalent at study enrolment
Number of patients with new-onset venous thromboembolism
Measured: 90 days after study enrolment
Number of days with any bleeding
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of days with major and/or fatal bleeding
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Number of red blood cell concentrates administered
Measured: 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
Measured: until discharge from the intensive care unit or up to 14 days after study inclusion
Length of stay in the intensive care unit
Measured: 90 days after study enrolment
Length of stay in the hospital
Measured: 90 days after study enrolment
Death
Measured: 90 days after study enrolment
Days alive and out of the intensive care unit
Measured: 90 days after study enrolment
Days alive and out of the hospital
Measured: 90 days after study enrolment
European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) index value
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.
Measured: 90 days after study enrolment
European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) visual analogue scale
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.
Measured: 90 days after study enrolment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Apr 2024
- Study start4 May 2024
- Primary completionMay 2027 (estimated)
- Study completionAug 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ThrombosisStudies of the same condition, open and under way.
- More trials run by Medical University of ViennaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 1,300 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Eva Schaden, Medical University of Vienna
- Investigators
- Eva Schaden, MD, Principal investigator, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06357403
- Sponsor's protocol ID
- AntiXa-ICU 1881/2023
- Acronym
- AntiXa-ICU
- Status last verified
- Jun 2026
- First submitted
- 19 Feb 2024
- Last updated
- 23 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 23 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Association of Anti-factor Xa Activity With Venous Thromboembolism in Critically Ill Patients: a Prospective Multicentre Cohort Study
- ClinicalTrials.gov ID
- NCT06357403
- Acronym / sponsor ID
- AntiXa-ICU / AntiXa-ICU 1881/2023
- Conditions
- Thrombosis, Pulmonary Embolism, Enoxaparin
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 1,300 participants (estimated)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- 4 May 2024 (actual)
- Primary completion
- May 2027 (estimated)
- Study completion
- Aug 2027 (estimated)
- First posted
- 10 Apr 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Intensive care unit patients | – | Diagnostic Test: Anti-factor Xa activity calibrated for enoxaparinPatients who are admitted to an participating intensive care unit who do not receive therapeutic anticoagulation. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients admitted to an surgical or medical intensive care unit who do not receive therapeutic anticoagulation
Key inclusion criteria (3 listed)
- 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
Key exclusion criteria (7 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Anti-factor Xa activity calibrated for enoxaparinAnti-factor Xa activity calibrated for enoxaparin | Diagnostic test | Intensive care unit patients |
Primary outcome
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.
25 secondary outcomes
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
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
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
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
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
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
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
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
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
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
Number of patients with venous thromboembolism
Time frame: prevalent at study enrolment
Number of patients with deep vein thrombosis
Time frame: prevalent at study enrolment
Number of patients with pulmonary embolism
Time frame: prevalent at study enrolment
Number of patients with new-onset venous thromboembolism
Time frame: 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
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
Number of red blood cell concentrates administered
Time frame: 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
Length of stay in the intensive care unit
Time frame: 90 days after study enrolment
Length of stay in the hospital
Time frame: 90 days after study enrolment
Death
Time frame: 90 days after study enrolment
Days alive and out of the intensive care unit
Time frame: 90 days after study enrolment
Days alive and out of the hospital
Time frame: 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
European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) visual analogue scale
Time frame: 90 days after study enrolment
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Jun 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Eva Schaden, MD principal investigator
Medical University of Vienna
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Thrombosis and Pulmonary Embolism, run by Medical University of Vienna at 3 sites in Austria.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 23 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Austria. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Christoph Dibiasi, MD (0043 1 40400 ext. 41020, christoph.dibiasi@meduniwien.ac.at), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
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). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jun 2026.