Antiphospholipid Antibody Levels in Early SLE May Predict Vascular Outcomes

High antiphospholipid (aPL) antibody levels in the early stages of systemic lupus erythematosus (SLE) may predict poorer patient outcomes, according to study data published in Rheumatology.

Investigators extracted clinical and laboratory data from a specialist SLE clinic at the University College London Hospital. The earliest available serum samples from 501 patients with SLE were retrieved from storage and tested for aPL antibody levels by enzyme-linked immunosorbent assay (ELISA). Specifically, ELISA was performed for the detection of the following 3 immunoglobin G (IgG) antibodies: anticardiolipin (aCL); anti-beta-2-glycoprotein I (anti-β2GPI); and anti-domain I (DI) of β2GPI. Lupus anticoagulant status, history of vascular events, and mortality data were obtained by medical record review. Kaplan-Meier analyses were performed to ascertain vascular event occurrence and mortality rates among patients with and without aPL in early disease.

Of the 501 patients who contributed data, 91% were women and 67% were white. Mean (SD) age at the time of serum sample collection was 30 (12.2) years. Per ELISA results, 190 (38%) patients were positive for 1 or more of IgG aCL, IgG anti-β2GPI, or IgG anti-DI. A total of 39 patients were double- or triple-ELISA-positive for any combination of the aPL markers. IgG antibodies to DI of β2GPI were most commonly detected, with 112 patients displaying positivity for anti-DI alone. Positivity for any of the 3 aPL was significantly more common in patients with lupus anticoagulant than in patients without (64% vs 31%; P =.0002).

Additionally, patients who were double- or triple-ELISA-positive were more likely to have or develop lupus anticoagulant than patients who were single-ELISA-positive or aPL-negative (23% vs 3%; P <.0001). Vascular history was available for 276 patients, among whom 83 (30%) had experienced a vascular event. Per the Kaplan-Meier analyses, patients with double- or triple-ELISA-positivity had nominally worse vascular outcomes (P =.06) compared with single-ELISA-positive or aPL-negative patients. Among 190 patients with any aPL positivity, 17.8% had died by the end of follow-up, compared with just 10.6% of aPL-negative patients (P =.022). 

These data suggest that early serum aPL positivity, particularly double- or triple-ELISA-positivity, may predict worse outcomes in patients with SLE. However, further research in a larger, long-term cohort is necessary to validate these findings and identify proper means of intervention.

Reference

Pericleous C, D’Souza A, McDonnell T, et al. Antiphospholipid antibody levels in early systemic lupus erythematosus: are they associated with subsequent mortality and vascular events? [published online June 30, 2019]. Rheumatology. doi:10.1093/rheumatology/kez239