The antiphospholipid syndrome (APS) (1) is defined by the development of vascular thrombosis, or pregnancy morbidity in the presence of persistent antiphospholipid antibodies (aPL). Antinuclear antibodies (ANA) can be detected in primary APS patients without any clinical systemic autoimmune disease. The presence of ANA antibodies could confer a specific phenotype in primary APS.

To evaluate the characteristics of APS patients with antinuclear antibodies without other autoimmune disease (ANA positive APS patients) in comparison with primary APS without ANA or secondary APS patients with associated systemic lupus erythematosus (SLE).

Clinical and biologic data from 195 APS were retrospectively collected and patients were classified as primary APS with positive ANA (ANA-positive APS), primary APS without any ANA (ANA-negative APS), and SLE-associated APS (SLE-APS).

Fourty patients (21%) were classified into ANA-positive APS group, 77 (39%) in ANA-negative APS and 78 (40%) in SLE-APS. In ANA-positive APS patients, 20 patients (51%) had arterial thrombosis, 14 (41%) had veinous thrombosis and 19% had obstetrical complications. There was no difference between the three groups for the frequency of thrombotic manifestations and obstetrical complications. ANA-positive APS patients had more non-criteria manifestations than ANA-negative APS (48% versus 25%; P≤0.01). ANA-positive APS had more triple aPL positivity (59% versus 18%; P<0.001) and more thrombosis and obstetrical recurrences (63% versus 36%; P<0.01) in comparison with ANA-negative APS patients. ANA-positive APS had more triple aPL positivity than SLE-APS patients (54% versus 33%; P<0.05). ANA-positive APS and SLE-APS patients had similar clinical manifestations, and recurrences. Despite a limited follow-up (28 months (11–50)) none of the ANA-positive APS develop SLE. Antiplatelet and anticoagulant therapies were similar for the three groups. SLE-APS patients received more immunomodulatory therapies.

ANA positivity in patients with APS enables to individualize a subset of patients with a more severe phenotype. Whereas the ANA positivity does not seem to be associated with the risk to develop SLE, prospective studies with a longer follow-up are necessary, in particular to evaluate the effect of additional therapies in this subset of APS.