Independent association of anti-β₂-glycoprotein I antibodies with macrovascular disease and mortality in scleroderma patients

Objective. Systemic sclerosis (SSc; scleroderma) is characterized by a unique widespread vascular involvement that can lead to severe digital ischemia, pulmonary arterial hypertension (PAH), or other organ dysfunction. Microthrombotic events and procoagulation factors such as anti-β2- glycoprotein I (anti-β₂GPI) or anticardiolipin antibodies (aCL) may be implicated in the development of these manifestations. This study was undertaken to investigate whether anti-β₂GPI and aCL are correlated with macrovascular disease, including ischemic digital loss and PAH, in SSc patients. Methods. Seventy-five SSc patients with a history of ischemic digital loss and 75 matched SSc controls were evaluated. Anticentromere antibodies (ACAs), anti-β₂GPI, and aCL were measured, and clinical associations were determined using conditional and simple logistic regression models. Results. Positivity for anti-β₂GPI was significantly more frequent in SSc patients with digital loss than in patients without digital loss (P = 0.017), with the IgA isotype of anti- β₂GPI showing the strongest association (odds ratio [OR] 4.0). There was no significant difference in aCL frequency between patients with digital loss and control patients. After adjustment for demographic characteristics, disease type, smoking, and ACA, anti-β₂GPI positivity was significantly associated with active digital ischemia (OR 9.4), echocardiographically evident PAH (OR 4.8), and mortality (OR 2.9). ACA positivity was associated with history of digital loss (OR 3.28), but not with PAH or mortality. History of digital loss was strongly associated with increased mortality (OR 12.5). Conclusion. Anti-β₂GPI is significantly associated with macrovascular disease in SSc and independently predicts mortality. It is unclear whether it has a pathogenetic role or simply reveals the presence of underlying endothelial injury. The use of anti- β₂GPI as a biomarker of vascular disease in SSc should be further explored.