The relevance of IgA anticardiolipin antibodies isotype (IgA aCL) in primary antiphospholipid syndrome (PAPS) remains controversial. The aim of our study was to explore the significance of IgA aCL positivity in patients with clinically diagnosed PAPS.
METHODSIn this cross-sectional study, we analyzed patients clinically diagnosed with APS, irrespective if they fulfilled Sydney classification criteria or not. To be included, patients needed to be tested for the presence of IgA aCL, measured by enzyme immunoassay and considered positive if values ≥ 20.1 APL. Patients who did not fulfill classification criteria should present a high probability for APS, defined as: (1) recurrent unprovoked thrombotic events (excluded other causes) or thrombotic events in the presence of one or more selected noncriteria manifestations (thrombocytopenia, livedo, aPL-valvopathy or aPL-nephropathy); or (2) positivity to at least one criteria aPL in one opportunity (not confirmed in follow-up tests). We then analyzed those two groups separately (classified and not classified). Statistical analysis was performed using Pearson chi-squared or Fisher's exact tests, as appropriate. The significance threshold was set at 5%.
RESULTSWe enrolled 182 PAPS patients; however, 33 patients did not perform IgA aCL and 2 patients from the not classified group did not meet the aforementioned definitions and were excluded. The remaining 147 patients were mostly women (88.4%) with median age of 46 years (39.0-55.0) and mean disease duration of 15.0 years (9.0-22.0). Of them, 130 were classified as PAPS, of which 119 (91.5%) had thrombotic and 58 (61.1%) had obstetric events. Seven patients (5.4%) of those who fulfilled classification criteria were positive for IgA aCL, meanwhile none of the 17 unclassified patients tested positive. We did not find any association of IgA aCL with clinical manifestations. On the other hand, the presence of IgA aCL was associated with persistent positivity for IgG and/or IgM aCL and antiß2glycoprotein1 (aß2GP1) isotypes (p = 0.005 and p = 0.006, respectively) in the classified group. High aCL titers (≥ 80 GPL/MPL) were also correlated to IgA aCL positivity (p = 0.005).
CONCLUSIONTesting for IgA aCL did not improve classification among PAPS patients that did not fulfill current classification criteria. In patients classified as PAPS, IgA aCL was related to the presence of IgG and/or IgM aCL or aß2GP1. No specific clinical manifestation was associated with IgA aCL. Our results reinforce that IgA aCL should not be routinely performed in Brazilian PAPS patients.
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