Do Patients with Antiphospholipid Syndrome Present with More Significant Venous Thromboembolic Clot Burden? A Retrospective Single-Center Study

TL;DR

This study found no evidence that patients with antiphospholipid syndrome have more severe venous blood clots compared to those without the condition.

Contribution

The study provides new clinical evidence that APS status does not correlate with increased clot burden in venous thromboembolic events.

Findings

APS patients had similar rates of significant clot burden as non-APS patients (38.7% vs 40.0%).

No clinical or laboratory predictors of significant clot burden were identified in multivariable analysis.

Triple-positive APS and primary APS were not associated with increased clot burden.

Abstract

Background/Objectives: Venous thromboembolic disease (VTE) is the most common initial manifestation of antiphospholipid syndrome (APS). Determining which patients with VTE to test for APS can be a challenging clinical decision. We aimed to determine if patients with APS present with more significant venous thromboembolic clot burden, as compared to patients with VTE without a diagnosis of APS. Methods: A multi-hospital single-institution retrospective cohort study was designed. Patients with a diagnosis of VTE who had been tested for APS from 1 December 2019 to 31 January 2022 were included. Patients were stratified based on the presence of APS (APS versus non-APS). Significant venous thromboembolic clot burden was defined as PE involving the main and/or lobar pulmonary arteries or DVT involving the iliofemoral veins. Assessment of clot burden was performed by review of radiology reports of the index clotting event. Results: We included 748 patients with a history of VTE who had been tested for APS; 75 patients (10%) were positive for APS. Significant clot burden was present in 29 (38.7%) APS patients and 269 (40.0%) non-APS patients (OR 0.95, 95% CI 0.58–1.56; p = 0.85). No predictors for significant clot burden were found on multivariable analysis. Triple-positive APS (OR 0.83, 95% CI 0.16–4.21; p = 0.82) and primary APS (OR 0.72, 95% CI 0.15–3.45; p = 0.68) were not associated with more significant clot burden. Conclusions: This retrospective single-institution analysis suggests that patients with APS may not present with more significant venous thromboembolic clot burden than patients with VTE without APS.

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