OBJECTIVES: This study focused on the prevalence and impact of antinuclear antibodies (ANA) in antiphospholipid antibody (aPL)-positive patients without concomitant systemic autoimmune rheumatic diseases (SARDs).

METHODS: Data from aPL-positive patients with or without Revised Sapporo APS classification criteria were retrieved from the APS ACTION Registry. Patients with concomitant SARDs were excluded.

RESULTS: 430 aPL-positive patients were included in the analysis, 56% ANA-positive and 44% negative. ANA positivity was significantly associated with history of hematologic manifestations (persistent autoimmune hemolytic anaemia, thrombocytopenia, leukopenia and/or lymphopenia) (16% of ANA-positive vs 7% of ANA-negative, p= 0.006). Triple aPL-positivity was more frequent in the ANA-positive subgroup (p= 0.02), along with low baseline C3 and C4 levels (p= 0.05 and p= 0.009, respectively), and higher frequency for extractable nuclear antigens (ENA). Among aPL-positive patients with no APS classification, ANA-positive patients showed a higher rate of arthritis (p= 0.006). Among female patients who have experienced at least one pregnancy, 113 were ANA-positive and 96 were ANA-negative; ANA-negative patients had a higher number of pregnancies (p= 0.018), and number of live births (p= 0.014). A wider proportion of ANA-positive patients were treated with hydroxychloroquine (HCQ) (p< 0.001).

CONCLUSION: When we analysed aPL-positive patients with no other SARDs, ANA status was not associated with thrombosis or pregnancy morbidity. Interestingly, ANA-positive patients showed higher rates of systemic autoimmune features, including hematologic manifestations, multiple aPL positivity, lower complement levels, ENA positivity, and joint involvement, and were more often treated with HCQ. Finally, aPL-positive subjects who were ANA-negative had a higher rate of pregnancies and live births.