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

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: Recruiting
• Conditions: Thrombosis; Pulmonary Embolism; Enoxaparin
• Intervention / Treatment: Diagnostic test: Anti-factor Xa activity calibrated for enoxaparin

• Study Type: Observational
• Enrollment (Estimated): 1300

Contacts and Locations

• Study Contact: Name: Christoph Dibiasi, MD; Phone Number: 41020 0043 1 40400; Email: christoph.dibiasi@meduniwien.ac.at

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

Eligibility Criteria

• 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

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
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.	until discharge from the intensive care unit or up to 14 days after study inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of patients with new-onset upper extremity deep vein thrombosis		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		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset central vein thrombosis		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		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		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		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		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset pulmonary embolism		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset symptomatic pulmonary embolism		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with new-onset incidental pulmonary embolism		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of patients with venous thromboembolism		prevalent at study enrolment
Number of patients with deep vein thrombosis		prevalent at study enrolment
Number of patients with pulmonary embolism		prevalent at study enrolment
Number of patients with new-onset venous thromboembolism		90 days after study enrolment
Number of days with any bleeding		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of days with major and/or fatal bleeding		until discharge from the intensive care unit or up to 14 days after study inclusion
Number of red blood cell concentrates administered		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		until discharge from the intensive care unit or up to 14 days after study inclusion
Length of stay in the intensive care unit		90 days after study enrolment
Length of stay in the hospital		90 days after study enrolment
Death		90 days after study enrolment
Days alive and out of the intensive care unit		90 days after study enrolment
Days alive and out of the hospital		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.	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.	90 days after study enrolment

Collaborators and Investigators

• Sponsor: Medical University of Vienna
• Investigators: Principal Investigator: Eva Schaden, MD, Medical University of Vienna

Study record dates

Study Major Dates

• Study Start (Actual): May 4, 2024
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): August 1, 2027

Study Registration Dates

• First Submitted: February 19, 2024
• First Submitted That Met QC Criteria: April 4, 2024
• First Posted (Actual): April 10, 2024

Study Record Updates

• Last Update Posted (Estimated): September 29, 2025
• Last Update Submitted That Met QC Criteria: September 23, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Respiratory Tract Diseases; Lung Diseases; Embolism and Thrombosis; Embolism; Pulmonary Embolism; Thrombosis; Molecular Mechanisms of Pharmacological Action; Fibrinolytic Agents; Fibrin Modulating Agents; Anticoagulants; Enoxaparin
• Other Study ID 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