Lupus patients are more likely to have high levels of prothrombotic antibodies that interact with cell membrane phospholipids (PLs), which are thought to be a possible cause of maternal morbidity. Now, researchers have identified a specific antiphospholipid antibody (aPL) that appears to predict the likelihood of pregnancy complications.
The study, “Lupus anticoagulant is the main predictor of adverse pregnancy outcomes in aPL-positive patients: validation of PROMISSE study results,” was published in the journal Lupus Science & Medicine.
The PROMISSE study (Predictors of pRegnancy Outcome: bioMarkers In antiphospholipid antibody Syndrome and Systemic lupus Erythematosus), a prospective multicenter observational study of pregnancies in 700 women with systemic lupus erythematosus (SLE) and/or aPL, was designed to identify clinical features, laboratory tests, and biomar-
kers that could be used to predict adverse outcomes after the first trimester of pregnancy.
Women enrolled in the study were followed monthly until delivery and tested for several aPLs, i.e., lupus anticoagulant (LAC), anticardiolipin antibodies (aCL), and anti-β2 glycoprotein I antibodies (aβ2GPI). Adverse pregnancy outcomes (APOs) included fetal death after 12 weeks of gestation, neonatal death, delivery prior to 36 weeks of gestation caused by pre-eclampsia or placental insufficiency, and reduced birth weight.
About one-third of the patients had APOs, with most occurring during the second trimester of pregnancy (80 percent). Within the antibodies measured, LAC was the only one associated with APOs and was present in 69 percent of patients who experienced adverse events, versus 27 percent of patients without APOs. In this subgroup of LAC-positive patients, the risk of APOs was found to be even higher in women with a previous history of thrombosis or who had tested positive for all three aPLs.
The researchers thought the study, despite some limitations, had notable strengths: it included patients from different centers analyzed according to the same criteria, and different assays were used to confirm LAC levels. “All PL assays were performed in core laboratories and international classification criteria were strictly followed. We determined LAC to be present if any of three screening tests (dRVVT, dPT or aPTT) followed by confirming tests were abnormal, because any single positive test was not predictive of outcomes and no single test was superior,” the authors said.
They concluded: “This study independently confirmed that LAC is the only aPL predictor of poor pregnancy outcomes after the first trimester of pregnancy in aPL-positive patients.”