Non-criteria antiphospholipid antibody profiles and thrombotic outcomes in a cohort of patients with systemic lupus erythematosus.

OBJECTIVES

Antiphospholipid syndrome (APS) is characterised by the presence of antiphospholipid antibodies (aPLs) and clinical outcomes of thrombosis and/or obstetric morbidity and is associated with systemic lupus erythematosus (SLE). IgG antiphosphatidylserine/prothrombin complex (aPS/PT), IgM aPS/PT and IgG anti-beta 2 glycoprotein 1-domain 1 (aβ2GP1-D1) are novel aPLs that have been associated with thrombosis; however, conclusive data are still lacking. It remains unclear how best to incorporate non-criteria autoantibodies into clinical decision-making. The aim of this study was to assess whether these novel aPLs were associated with an increased risk of thrombosis in patients with SLE.

METHODS

We evaluated 341 patients enrolled in the SouThern Alberta Registry for Lupus EryThematosus database with SLE by the American College of Rheumatology or Systemic Lupus International Collaborating Clinics classification criteria. Medical records were reviewed between March 2006 and January 2021 for thrombotic events and serology results for lupus anticoagulant, IgG anticardiolipin, IgG anti-beta 2 glycoprotein 1 (aβ2GP1), IgG aPS/PT, IgM aPS/PT and IgG aβ2GP1-D1.

RESULTS

Among 341 patients with SLE, 59 (17%) met the revised Sapporo lab criteria, and of those 29 (49%) had a major thrombotic event (OR 3.5, 95% CI 1.9 to 6.3). Among 142 patients who had at least one positive non-criteria autoantibody, 45 (32%) had a major thrombotic event (OR 1.6, 95% CI 0.97 to 2.6). In a univariate analysis, the IgG aPS/PT and IgG aβ2GP1-D1 were associated with major and all thrombotic events. In a multivariate analysis that controlled for age, sex, prednisone use, SLE disease activity (Systemic Lupus Erythematosus Disease Activity Index-2K and the revised Sapporo lab criteria, among the non-criteria aPLs, only IgG aPS/PT was associated with an increased risk of a major thrombosis (OR 2.2, 95% CI 1.1 to 4.5).

CONCLUSIONS

In our multivariate analysis, IgG aPS/PT was associated with a modestly increased risk of thrombotic events.