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RecruitingNCT06357403AntiXa-ICUUpdated Jun 23, 2026

Association of Anti-factor Xa Activity With Venous Thromboembolism in Critically Ill Patients

An observational study in Thrombosis, Pulmonary Embolism and Enoxaparin, sponsored by Medical University of Vienna. Recruiting at 3 sites in Austria. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-23.

Sponsored by Medical University of Vienna · Observational

Study type
Observational
Model
Cohort
Time perspective
Prospective
Enrollment
1,300
Ages
18 Years and older
Sex
All
01

Study 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. 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.
02

Conditions studied

  • Thrombosis
  • Pulmonary Embolism
  • Enoxaparin
03

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
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

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

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
04

Study design

Observational model
Cohort
Time perspective
Prospective
Enrollment
1,300 participants (estimated)
Patient registry
No

Groups and cohorts

  • 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

Interventions

  • Diagnostic testAnti-factor Xa activity calibrated for enoxaparin

    Anti-factor Xa activity calibrated for enoxaparin

05

What researchers measure

Primary outcomes

  1. 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.

    Time frame: until discharge from the intensive care unit or up to 14 days after study inclusion

Secondary outcomes

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. Number of patients with venous thromboembolism

    Time frame: prevalent at study enrolment

  12. Number of patients with deep vein thrombosis

    Time frame: prevalent at study enrolment

  13. Number of patients with pulmonary embolism

    Time frame: prevalent at study enrolment

  14. Number of patients with new-onset venous thromboembolism

    Time frame: 90 days after study enrolment

  15. Number of days with any bleeding

    Time frame: until discharge from the intensive care unit or up to 14 days after study inclusion

  16. 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

  17. Number of red blood cell concentrates administered

    Time frame: until discharge from the intensive care unit or up to 14 days after study inclusion

  18. 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

  19. Length of stay in the intensive care unit

    Time frame: 90 days after study enrolment

  20. Length of stay in the hospital

    Time frame: 90 days after study enrolment

  21. Death

    Time frame: 90 days after study enrolment

  22. Days alive and out of the intensive care unit

    Time frame: 90 days after study enrolment

  23. Days alive and out of the hospital

    Time frame: 90 days after study enrolment

  24. 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.

    Time frame: 90 days after study enrolment

  25. 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.

    Time frame: 90 days after study enrolment

06

Study locations

3 of 3 sites recruiting
  • Department of Internal Medicine, Medical University of Graz
    Graz, Styria 8063, Austria
    • Philipp Eller, Prof. · Contact
    Recruiting
  • Division of Intensive Care and Emergency Medicine, Department of Internal Medicine, Medical University Innsbruck
    Innsbruck, Tyrol 6020, Austria
    Recruiting
  • Department of Anaesthesia, Intensive Care Medicine and Pain Medicine, Medical University of Vienna
    Vienna, 1090, Austria
    • Christoph Dibiasi, MD · Contact
    Recruiting
07

References and documents

Individual participant data

Plan to share: Undecided

No publications or documents are linked to this record.

08

Registry details

Key details

Study ID
NCT06357403
Lead sponsor
Medical University of Vienna
Responsible party
Eva Schaden (Assoc. Prof. Dr., Medical University of Vienna) — Principal investigator
First posted
Apr 10, 2024
Start date
May 4, 2024
Primary completion
May 2027 (estimated)
Completion
Aug 2027 (estimated)
Last update
Jun 23, 2026

Study contacts

Christoph Dibiasi, MD
Contact
christoph.dibiasi@meduniwien.ac.at
0043 1 40400 ext. 41020
Eva Schaden, MD
principal investigator · Medical University of Vienna

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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