The role of lupus anticoagulant and triple marker positivity as risk factors for rethrombosis in patients with primary antiphospholipid syndrome.

Objectives: To ascertain rethrombotic risk factors in patients with primary antiphospholipid syndrome (PAPS).
Methods: We retrospectively evaluated 95 patients according to their rethrombotic status. We registered anticoagulation (OA) status, comorbidities, traditional thrombotic factors, prevalence of aCL (IgG-IgM), anti-β2GP-I (IgG-IgM), LA and triple marker positivity (LA, aCL and anti-β2GP-I).
Results: Forty-two patients had rethrombosis and 53 were rethrombosis-free. The median follow-up was 4.5 (0.3-26) years. There were no differences in comorbidities and traditional thrombotic factors. Patients with rethrombosis had more frequently LA (62% vs. 40%, p=0.04), were younger (41 vs. 47 years, p=0.01) and received less frequently OA (23% vs. 54%, p=0.002). A logistic regression analysis showed that the OA status (OR 0.17, 95% CI 0.05-0.57, p=0.004) and age (OR 0.94, 95% CI 0.90-0.98, p=0.01) remained significant. Patients who discontinued OA and developed rethrombosis (Group 1, n=32) vs. patients who discontinued OA, but remained rethrombosis-free (Group 2, n=24) were also analysed. We found a higher prevalence of LA and triple marker positivity in Group 1 (67% vs. 31%; OR= 4.5, 95% CI 1.3-14.9, p= 0.01 and 57% vs. 27%; OR 3.6, 95% CI 1.7-12; p=0.03), respectively. Both variables remained associated with rethrombosis when compared with the overall rethrombosis group vs. Group 2 (LA 62% vs. 31%, OR= 3.6 95% CI 1.1-11.2, p=0.03; triple marker 54% vs. 27%; OR 32 95% CI 1.01-10.2, p=0.05).
Conclusions: LA positivity and triple aPL positivity confer a more severe risk of rethrombosis in PAPS patients, irrespective of their anticoagulation status and known conventional risk factors.