according to study findings presented at the European Congress of Rheumatology.
Spanish researchers found that the number of antiphospholipid (aPL) antibodies present was important for the development of antiphospholipid syndrome (APS) and that lupus anticoagulant (LA) was the major aPL antibody linked to systemic lupus erythematosus (SLE)–related organ involvement.
“aPL [antibodies] has been extensively associated with an increased risk of thrombosis and poor pregnancy outcomes, mainly in patients with primary APS,” study investigator Leyre Riancho-Zarrabeitia, MD, PhD, explained in an interview ahead of the congress.
“Moreover, aPL [antibody] positivity in SLE has been proposed to be associated with higher damage accrual and with certain manifestations such as valvular heart disease, pulmonary hypertension, and neuropsychiatric manifestations,” she added.
Anticardiolipin antibodies – notably IgG rather than IgM isotypes – also seemed to play an important role in APS and SLE manifestations, Dr. Riancho-Zarrabeitia, of Hospital Sierrallana, Instituto De Investigación Marqués De Valdecilla, and the University of Cantabria (Spain), noted during her oral presentation.
She reported data on 3,651 patients included in the RELESSERbetween October 2011 and August 2012. This large, multicenter, hospital-based registry retrospectively collects immunologic, clinical and demographic data from unselected adult patients with SLE who are attending 45 Spanish rheumatology services within the country’s national health system.
Over one-third (37.5%) of patients, who had a mean age of 47 years and were mostly (90%) women, were positive for aPL. The most frequent aPL detected was IgG anticardiolipin (aCL) antibodies, seen in 25% of patients, followed by LA in 24%, and IgM aCL in 20%.
Of the aPL-positive patients, 20.6% were positive for only one antibody, 12.1% were positive for two antibodies, and 4.8% were positive for three antibodies.
“All types of aPL were associated with classic APS manifestations,” Dr. Riancho-Zarrabeitia said. The associations were strongest for thrombotic events, such as arterial and venous small-vessel thrombosis and recurrent early pregnancy losses.
aCL antibodies conferred the highest risk for arterial thrombosis, she noted (odds ratio, 5.7), whereas LA conferred the highest risk for venous thrombosis (OR, 4.7). Both IgG and IgM isotypes were associated with thrombotic events, fetal death and recurrent pregnancy loss, but the association was stronger with the IgG isotypes.
Having more than one aPL was particularly associated with a higher risk of these APS manifestations. For example, when one antibody was present the OR for arterial thrombosis was 4.45, but when two or more aPL were detected, the ORs rose to 9.23 and 15.6, respectively.
aCL and LA also were associated with thrombocytopenia and hemolytic anemia, with ORs of around 1-2 and 2-3 respectively. There also were antibody associations with cognitive impairments.
Similar results were seen in patients with SLE. “aPL [antibody] positivity in SLE patients influenced the risk for thrombotic and obstetric manifestations,” Dr. Riancho-Zarrabeitia said. LA and aCL were associated with an increased risk of neuropsychiatric manifestations, and LA was linked to an increased risk for renal disease.
The risk for specific SLE manifestations was again higher with IgG isotypes of aCL, notably an increased risk for cardiac and respiratory events.
While increased antibody numbers generally led to a higher risk of complications, the risk for cutaneous manifestations decreased.
“The load of aPL [antibodies] confers a higher risk for APS,” Dr. Riancho-Zarrabeitia said during her conclusion. “Regarding systemic lupus erythematosus, the number of positive antibodies is directly associated with neurological and ophthalmological manifestations, and inversely associated with cutaneous manifestations.”
What these findings show, said Dr. Riancho-Zarrabeitia in the precongress interview, is that individuals who test positive for aPL antibodies need careful monitoring to prevent and treat severe manifestations. “The next step would be to confirm our findings with a prospective study.”
Dr. Riancho-Zarrabeitia has received travel grants from AbbVie, Pfizer, UCB, Merck, GlaxoSmithKline, Amgen, and Roche.
SOURCE: Riancho-Zarrabeitia L et al. Ann Rheum Dis. Jun 2019;78(Suppl 2):136-7. Abstract OP0124.