Prevalence and Thrombotic Risk Assessment of Anti-β2 Glycoprotein I Domain I Antibodies: A Systematic Review

Background To date, the exact prevalence of anti- (2) glycoprotein I domain I (anti- (2) GPI-DI) antibodies in patients with antiphospholipid syndrome (APS) and their role when assessing thrombosis risk is uncertain. Objectives To estimate the prevalence of anti- (2) GPI-DI in patients with APS and to determine whether anti- (2) GPI-DI-positive individuals are at greater risk of thrombosis, as compared with individuals without anti- (2) GPI-DI, by systematically reviewing the literature. Methods A detailed literature search was applied a priori to Ovid MEDLINE In-Process and Other Non-Indexed Citation 1986 to present and to abstracts from the European League Against Rheumatism (EULAR) and American College of Rheumatology (ACR)/Association for Rheumatology Health Professionals (ARHP ) Annual Meetings (2011-2015). Results A total of 11 studies, including 1,585 patients, were analyzed. Patients were distributed as follow: 1,218 patients APS (45.4% anti- (2) GPI-DI-positive; in more detail: 504 primary APS [55.4% anti- (2) GPI-DI-positive], 192 secondary APS [43.2% anti- (2) GPI-DI-positive], and 522 not specified), 318 with systemic lupus erythematosus (SLE; 26.7% anti- (2) GPI-DI-positive), 49 asymptomatic carriers of antiphospholipid antibodies (aPL) (30.6% anti- (2) GPI-DI-positive), and 1,859 healthy controls. When considering the five studies eligible for thrombotic risk assessment, four studies found a significant association of anti- (2) GPI-DI-positivity with thrombotic events, whereas one study found no predictive correlation with thrombosis (overall odds ratio [OR] for pooled data: 1.99; 95% confidence interval [CI]: 1.52-2.6; p <0.0001). Conclusion We report an overall estimated median prevalence of anti- (2) GPI-DI antibodies of 44.3% in patients with APS and/or SLE and a significantly higher prevalence among patients with APS compared with SLE alone. Anti- (2) GPI-DI antibodies might represent a promising tool when assessing thrombotic risk in patients with APS.