Thrombotic Antiphospholipid Syndrome: Recurrent Thromboses

Thrombotic antiphospholipid syndrome (APS) is a condition affecting young people in whom a thromboembolic event occurs in the presence of circulating antiphospholipid antibodies (aPL).

was to evaluate the incidence of recurrent thrombosis and its risk factors in antiphospholipid syndrome.

. The retrospective study included 98 patients with APS who were followed up at the institute from 2014 to 2023, of whom 66 (67%) were women and 32 (33%) were men. Of the 98 patients with APS, 48 (49%) had a diagnosis of systemic lupus erythematosus (SLE). Antiphospholipid antibodies (aPL), including the antibodies to cardiolipin (IgG/IgM aCL), antibodies to ß2glycoprotein 1 (IgG/IgM aß2GP1), antibodies to ß2 glycoprotein IgG against domain 1 (IgG aß2GP1-D1), antibodies to phosphatidylserine/prothrombin complex (IgG/IgM aPS/PT), and other thrombotic risk factors were determined. aPL was assessed by enzyme-linked immunosorbent assay (ELISA) and chemiluminescence assay (CLA).

: Thrombosis recurrence was reported in 62 (63%) of 98 patients, and in 36 (35%) it was not reported. The main cause of recurrent thrombosis was treatment with direct oral anticoagulants (DOACs). Twenty-four (38.7%) of  62 patients with recurrent thrombosis were treated with DOACs, the duration of which ranged from 6 to 24 months. The next most common cause of recurrent thrombosis was the lack of continuous anticoagulant therapy in 20 (32.5%) patients. In 17 (27.4%) patients, recurrence occurred while they were still taking warfarin. In 10 (41.7%) of the 24 patients, the recurrent thrombosis was arterial in origin. This was associated with recurrent cerebral circulation problems. The level of positivity for aPL did not matter, but all of them had triple IgG-aPL positivity. Five patients had lupus anticoagulant (LA) at the onset of the disease before anticoagulant therapy. IgG-aPS/PT was most important in association with recurring thrombosis in the ELISA: 45 (72.6%) of 62 patients with recurring thrombosis were positive for IgG-aPS/PT as compared with 19 (52.8%) of 36 patients without recurring thrombosis. The detection of all aPLs was more frequent in CLA than in ELISA. However, the determination of aPL by ELISA is recommended according to the latest classification criteria. Triple positivity for IgG aCL, IgG aß2GP1, and IgG aß2GP1-D1 according to CLA data remained a risk factor for recurrent thrombosis and increased the risk of recurrence more than 3 times. Obesity was a risk factor for recurrent thrombosis, with a 5-fold increased risk of recurrent thrombosis in obese patients compared to the non-obese ones (p = 0.01).

. Recurrent thrombosis in APS is largely associated with IgG aCL, IgG aß2GP1, IgG aß2GP1-D1, and IgG aPS/PT. Triple IgG aPL positivity in any combination significantly increased recurrent thrombosis risk. The presence of any type of IgG aPL in both ELISA and CLA influenced the recurrence rate of thrombosis in APS. Obesity was a significant risk factor for recurrent thrombosis.