Comparative analysis of clinical spectrum and outcomes in primary and secondary antiphospholipid syndrome

Background
Antiphospholipid syndrome (APS) is an autoimmune disease that predispose to venous, arterial thrombotic events or both as well as pregnancy complications. APS is classified as either primary, or secondary APS, which develops in association with autoimmune disorder, commonly systemic lupus erythematosus (SLE).


Objective
We aimed to compare the clinical presentations and outcomes in patients with primary and secondary APS, with a focus on identifying risk factors of thrombotic relapse.


Results
The study involved 48 (92.3%) females and four (7.7%) males, with a mean age of 30.7 ± 8.5 years, and mean disease duration of 3.8 ± 2.7 years. 50% of the patients were diagnosed as primary APS, and 50% were secondary to systemic lupus erythematosus. The obstetric complications, in the form of recurrent abortions or pregnancy-related complications reported in 22 (42.3%) patients. Thrombotic complications were the most common presentation among our patients, as 39 (75%) patients experienced thrombotic events, 34.6% with a single thrombotic event, and 40.4% with recurrent thrombotic attacks. A multivariate logistic regression model identified that anti-β2 glycoprotein I (GPI) immunoglobulin G (IgG) levels as the only statistically significant independent predictor of thrombosis recurrence in APS patients. The receiver operating characteristic analysis for anti-β2 GPI IgG titre yielded an area under the curve of [0.878], with (95% CI: 0.758–0.999). Sensitivity was 76.2%, specificity and positive predictive value was 88.9% for each.


Conclusion
Anti-β2 GPI IgG titre is a reliable biomarker for identifying APS patients at higher risk of thrombotic relapse.