Observational Study to Evaluate the Effectiveness of DOACS for Secondary Thrombosis Prevention in Low-risk Thrombotic APS Patients (DOACS-APS)

Real-world Observational Study to Evaluate the Effectiveness and Safety of Direct Oral Anticoagulants Compared With Vitamin K Antagonists for Secondary Thrombosis Prevention in Low-risk Thrombotic Antiphospholipid Syndrome Patients

This is an observational study designed to evaluate the effectiveness and safety of direct oral anticoagulants (DOACs) compared with vitamin K antagonists (VKAs) for the secondary prevention of thrombosis in patients with low-risk thrombotic antiphospholipid syndrome.

Antiphospholipid syndrome is an autoimmune disorder associated with an increased risk of thrombotic events. Although VKAs have traditionally been the standard treatment, DOACs are increasingly used in clinical practice in selected patients, despite limited evidence in this setting.

This study includes patients with previous venous thrombosis and a low-risk serological profile who are treated with either DOACs or VKAs according to routine clinical practice. The primary objective is to compare thrombotic recurrence and bleeding events between both treatment strategies.

The results of this study will contribute to improving knowledge about the use of DOACs in patients with low-risk thrombotic antiphospholipid syndrome.

Study Overview

• Status: Recruiting
• Conditions: Thrombophilia; Antiphospholipid Syndrome (APS); Venous Thrombosis (Disorder)

Detailed Description

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the occurrence of arterial, venous, or small-vessel thrombosis in the presence of persistent antiphospholipid antibodies. Patients with thrombotic APS have a high risk of recurrent thrombosis and require long-term anticoagulation. Vitamin K antagonists (VKAs) have traditionally been the treatment of choice in this population.

Direct oral anticoagulants (DOACs) have demonstrated efficacy and safety in other clinical settings, such as venous thromboembolism and non-valvular atrial fibrillation. However, their use in APS remains controversial following randomized clinical trials that showed an increased risk of arterial thrombotic events, particularly in patients with high-risk serological profiles.

Current clinical guidelines suggest that DOACs may be considered in selected patients with low-risk thrombotic APS, defined by venous thrombosis and the absence of triple antiphospholipid antibody positivity. Nevertheless, evidence supporting their use in this specific subgroup is limited.

This observational, analytical, ambispective (retrospective and prospective) study aims to evaluate the effectiveness and safety of DOACs compared with VKAs in patients with low-risk thrombotic APS under routine clinical practice conditions.

Adult patients with a diagnosis of low-risk thrombotic APS who are receiving treatment with DOACs or VKAs at the time of inclusion will be eligible. Anticoagulant therapy will be prescribed at the discretion of the treating physician, with no intervention by the study protocol.

The primary objective is to assess a combined effectiveness and safety endpoint, including thrombotic recurrence and major or clinically relevant bleeding. Secondary objectives include all-cause mortality, cardiovascular mortality, and treatment-related quality of life assessed using the Anti-Clot Treatment Scale (ACTS).

The study will be conducted in Internal Medicine units across Spain and is expected to provide relevant real-world evidence to support clinical decision-making in the anticoagulant management of patients with low-risk thrombotic antiphospholipid syndrome.

• Study Type: Observational
• Enrollment (Estimated): 600

Contacts and Locations

• Study Contact: Name: Anabel Franco Moreno, MD, PhD; Phone Number: +34686102661; Email: afranco278@hotmail.com
• Study Contact Backup: Name: Isabel Perales Fraile, MD; Email: isabelperalesf@gmail.com

Study Locations

• Spain
  • Madrid
    • Madrid, Madrid, Spain, 28031
      • Recruiting
      • Hospital Universitario Infanta Leonor
      • Contact: Anabel Franco-Moreno, MD, PhD; Phone Number: 686102661; Email: afranco278@hotmail.com
    • Madrid, Madrid, Spain
      • Recruiting
      • Hospital Universitario Infanta Sofía
      • Contact: Isabel Perales Fraile, MD; Email: isabelperalesf@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This study includes adult patients with low-risk thrombotic antiphospholipid syndrome managed in routine clinical practice at Internal Medicine units in Spain. Eligible patients have a history of venous thrombotic events and a low-risk antiphospholipid antibody profile and are treated with either direct oral anticoagulants or vitamin K antagonists at the discretion of the treating physician. The study combines retrospective and prospective data collection and does not involve any intervention beyond standard clinical care.

Description

Inclusion Criteria:

• Adults (≥18 years) with a diagnosis of thrombotic antiphospholipid syndrome.
• Low-risk antiphospholipid syndrome defined by previous venous thrombosis and a single or double positive antiphospholipid antibody profile (lupus anticoagulant, anticardiolipin antibodies, and/or anti-beta-2-glycoprotein I antibodies).
• Patients receiving long-term anticoagulant treatment with direct oral anticoagulants or vitamin K antagonists according to routine clinical practice.
• At least 2 weeks of continuous anticoagulant treatment before study inclusion.

Exclusion Criteria:

• Age <18 years.
• Triple antiphospholipid antibody positivity.
• History of arterial thrombosis.
• Anticoagulation for indications other than secondary prevention of venous thrombosis related to antiphospholipid syndrome.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Patients with low-risk thrombotic antiphospholipid syndrome receiving direct oral anticoagulants; Patients with low-risk thrombotic antiphospholipid syndrome receiving direct oral anticoagulants for secondary prevention of venous thrombosis according to routine clinical practice. Treatment choice is made by the treating physician, with no intervention
Patients with low-risk thrombotic antiphospholipid syndrome receiving vitamin K antagonist; Patients with low-risk thrombotic antiphospholipid syndrome receiving vitamin K antagonists for secondary prevention of venous thrombosis according to routine clinical practice. Treatment choice is made by the treating physician, with no intervention

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occurrence of recurrent venous thrombosis	Occurrence of recurrent venous thrombosis during follow-up.	24 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Major or clinically relevant non-major bleeding	Occurrence of major bleeding or clinically relevant non-major bleeding events during follow-up.	24 months

Collaborators and Investigators

• Sponsor: Infanta Leonor University Hospital
• Collaborators: pInvestiga
• Investigators: Principal Investigator: Anabel Franco-Moreno, MD, PhD, Sociedad Española De Medicina Interna

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2025
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: January 20, 2026
• First Submitted That Met QC Criteria: January 20, 2026
• First Posted (Actual): January 28, 2026

Study Record Updates

• Last Update Posted (Actual): January 30, 2026
• Last Update Submitted That Met QC Criteria: January 28, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Observational study; Vitamin K antagonists; Direct oral anticoagulants; Venous Thrombosis; Real-world study; Low-risk antiphospholipid syndrome; Secondary thrombosis prevention; Antiphospholipid Antibody Profile
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Autoimmune Diseases; Immune System Diseases; Hematologic Diseases; Embolism and Thrombosis; Thrombosis; Hemic and Lymphatic Diseases; Venous Thrombosis; Thrombophilia; Antiphospholipid Syndrome
• Other Study ID Numbers: DOACS-APS

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data that underlie the results reported in publications arising from this study will be made available upon reasonable request. Data will be shared after publication of the primary results, subject to approval by the study investigators and in accordance with applicable ethical and legal requirements. Requests must include a methodologically sound research proposal, and data will be provided under a data sharing agreement to ensure participant confidentiality.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No