TOPLINE:

Among patients with new-onset systemic lupus erythematosus (SLE), 23% experienced one or more thromboembolic events (TEs). The incidence of TEs in antiphospholipid antibody-positive patients diagnosed with antiphospholipid syndrome (APS) was highest during the first year and declined thereafter.

METHODOLOGY:

• Researchers conducted a population-based study to assess the incidence of TEs and APS relative to the onset of SLE among patients with new-onset SLE and the effect of antiphospholipid antibody status.
• They assessed the data of 700 patients with new-onset SLE (mean age at diagnosis, 39 years; 85% women) diagnosed in Southeast Norway between 2000 and 2017, with a mean follow-up duration of 8 years.
• Antiphospholipid antibody status was assessed using lupus anticoagulant, anticardiolipin, and anti-beta-2 glycoprotein assays, which was classified as positive or negative according to international guidelines.
• The presence of APS was confirmed if it was diagnosed by a physician or if the patient met the defined APS classification criteria. Those who had a positive antiphospholipid antibody status without APS were defined as carriers.
• Outcomes assessed were the occurrence of APS, fatal or non-fatal TEs, and mortality. TEs were defined as arterial TEs and/or venous TEs identified using medical records.

TAKEAWAY:

• At the end of follow-up, 11% of patients with new-onset SLE had developed APS, with 35% of these cases occurring within 1 year of SLE diagnosis. Overall, 156 patients (23%) with new-onset SLE had at least one TE and 89 experienced the first TE after SLE diagnosis.
• Incidences of TEs accumulated around SLE diagnosis and were highest within 1 year of diagnosis. This was particularly seen in antiphospholipid antibody-positive patients with APS for whom the incidence of TEs was 59 per 100 person-years in the first year of SLE, and it was 2.6 per 100 person-years among patients without APS. A decline in the incidence of TEs was seen in the subsequent 4 years.
• The probability of remaining free of TEs was significantly lower in patients who were positive vs negative for antiphospholipid antibody at 1 year after SLE diagnosis (0.88 vs 0.98; P < .001). The standardised mortality rate in patients with and without APS was 4.7 and 1.7, respectively.
• Factors such as male sex, older age, smoking, the presence of haemolytic anaemia, and more than one antiphospholipid antibody positivity were individually associated with an increased risk for TEs (P < .05 for all).

IN PRACTICE:

"We identify a high risk of thrombosis, around SLE diagnosis, particularly in aPL [antiphospholipid antibody] positive patients, indicating suboptimal management of thromboembolic risk in this population. Heightened awareness of TE at the time of SLE diagnosis appears crucial, underscoring the need for early risk assessment and targeted prevention strategies," the authors wrote.

SOURCE:

This study was led by Sigrid Reppe Moe, Department of Rheumatology, Oslo University Hospital, Oslo, Norway. It was published online on September 02, 2025, in RMD Open.

LIMITATIONS:

This study lacked data on traditional risk factors for TEs. The timing of TEs and SLE diagnosis was only available at a yearly level. The cohort study design did not infer causality.

DISCLOSURES:

This study received support from the DAM Foundation, Norwegian Women's Public Health Association, Vivi Irene Hansen's Foundation, Ragna and Egil Eiken's Foundation, and Norwegian Rheumatism Association. Some authors reported being engaged by various pharmaceutical companies, including AstraZeneca, GSK, Novartis, and UCB.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.