Positive Antiphospholipid Levels in SLE Linked to Increased Risk for Vascular Events

In patients with early systemic lupus erythematosus (SLE), positive antiphospholipid antibodies (aPLs), including immunoglobulin G anticardiolipin (IgG anti-CL), IgG antibeta2glycoprotein I (anti-β2GPI), and antidomain I of beta2glycoprotein (anti-DI), are associated with an increased risk for subsequent vascular events, according to the results of a single-center cohort study published in Rheumatology (Oxford).

It is well known that although aPLs are detected in 20% to 30% of patients with SLE, not all of these individuals go on to develop vascular events.

Researchers conducted a study to determine the link between aPLs and risk for vascular events in SLE.

Serum samples, collected from patients with early SLE, were tested for presence of IgG anti-CL, anti-β2GPI, and anti-DI, using enzyme-linked immunosorbent assays (ELISAs).

Participants from the lupus cohort at University College London Hospital who met the American College of Rheumatology (ACR) criteria for SLE were enrolled in the study.

Of 501 patients with SLE from whom serum samples were collected, complete history on vascular events and aPL measurements were available for 423; 23 patients were excluded from the study because a vascular event was reported prior to SLE diagnosis.

Of the 400 included participants, 154 (38.5%) were tested positive for at least 1 aPL (aPL-positive), 246 (61.5%) were tested aPL-negative, 27 (6.8%) were tested double/triple-positive, and 127 (31.8%) were tested single-positive. The most common antibody, which was found in 108 (27%) of the participants, was IgG-anti-DI.

Over a median follow-up period of 13 years, 91 vascular events were reported in 77 patients (54 arterial and 37 venous vascular events), among whom 42 (55%) were tested aPL-positive and 18 (23%) were tested positive for IgG anti-DI only.

Of note, participants with aPL positivity vs negativity were significantly more likely to develop a vascular event (P =.041). When comparing patients with double/triple, single-positive, and negative aPLs, a statistically significant difference was observed between the groups (P =.0057), with the highest risk for a vascular event reported among patients with double/triple-positive aPLs.

The study was limited by the fact that the researchers did not have available data on lupus anticoagulant positivity because it could not be evaluated from stored samples. Additional limitations included the single-center cohort and that the ELISA results were derived from an in-house assay in which IgM and r IgA antibodies were not measured.

The study authors concluded, “Our results suggest that patients with SLE who test positive for [at least] 2 of IgG anti-DI, anti-CL and anti-β2GPI, even at low levels, at the time of diagnosis, may warrant more frequent aPL testing and consideration of aspirin.”

Disclosure: Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.