Risk factors and recurrent thrombosis in primary antiphospholipid syndrome

Aim: The study aims to evaluate the incidence of recurrent thromboses in patients with primary antiphospholipid syndrome (PAPS) and its association with the presence of different antiphospholipid antibodies (aPLs) and known thrombogenic risk factors. Methods: This retrospective study included 52 patients. The median age of the patients was 38.5 years [31.5; 43.5], and the duration of the disease was 9.0 years [3.1; 13.0]. aPLs, including IgG/IgM/IgA antibodies to cardiolipin (aCLs), IgG/IgM/IgA anti-beta2-glycoprotein I (anti-β2-GPI), IgG anti-domain I-β2-GPI (anti-β2-GPI DI) antibodies, IgG/IgM antibodies to the phosphatidylserine/prothrombin complex (aPS/PT), and other thrombosis risk factors were included for analysis. Results: Recurrent thrombosis was reported in 34 (65%) out of 52 patients and 18 (35%) did not have it. The main reason for the recurrence of thrombosis was the lack of anticoagulant therapy: in 18 (52.9%) out of 34 patients with recurrent thrombosis. Three patients were taking warfarin at the time of thrombosis recurrence, but target international normalized ratio (INR) levels were not achieved. Other patients with recurrent thrombosis were taking direct oral anticoagulants (DOACs). The risk of recurrent thrombotic events with positive IgG aCL was 10.33 (P = 0.002) and 21 (P = 0.007) times higher were examined in enzyme-linked immunoassay (ELISA) and chemiluminescent assay (CLA), respectively. The risk of thrombosis was 4.58 times higher in patients who were IgA aCL-positive (P = 0.01). Compared with other antibodies, with positive IgG values of anti-β2-GPI and IgG aPS/PT by ELISA, a lower probability of thrombosis recurrence was observed: 7.56 and 7.25, respectively. A high risk of recurrent thrombosis [odds ratio (OR) = 32.0] was observed in IgG anti-β2-GPI (CLA). The combination of IgG aCL with IgG anti-β2-GPI and with IgG anti-β2-GPIDI is more informative with respect to the risks of thrombosis recurrence compared to double positivity for aCL with anti-β2-GPI (OR = 20.71 vs. OR = 10.18). Triple positivity for IgG aCL with IgG anti-β2-GPI and with IgG aPS/PT also shows better results compared to positivity for aCL with anti-β2-GPI (OR = 6.06 vs. OR = 5.79). Among other risk factors, arterial hypertension (AH) and obesity were significant in relation to the recurrence of thrombosis. AH occurred in 22 (42%) of 52 patients with PAPS. AH was associated with recurrent thrombosis in PAPS patients: 18 (53%) out of 34 with recurrent thrombosis had AH versus 4 out of 18 without recurrent thrombosis (P = 0.003). Conclusions: Recurrent thrombosis in antiphospholipid syndrome (APS) is largely associated with IgG aCL, IgG anti-β2-GPI, IgG anti-β2-GPIDI, IgG aPS/PT, and IgA aCL positivity. AH was a significant risk factor for recurrent thrombosis.