Diagnostic value of anti-annexin A5 antibodies in seropositive versus seronegative antiphospholipid syndrome patients

Abstract

Background: Current laboratory criteria for antiphospholipid syndrome (APS) classification recommend testing positive for antiphospholipid (aPL) antibodies. However, there appears to be a subset of patients with classical APS manifestations who test negative. Aim of the work: To analyze the potential clinical usefulness of testing for anti-annexin A5 antibodies in patients with APS and to study the effectiveness of testing for non-criteria aPLs in an attempt to increase the diagnostic yield, particularly in seronegative APS. Patients and methods: 60 APS patients were divided into two groups; 30 seropositive (SP-APS) (group I) and 30 age and sex matched seronegative (sN-APS) testing negative for aPL antibodies. Serum assay for detection of isotypes of anti-annexin A5 antibodies (IgG and IgM) were conducted. Results: The mean age of the patients was 32.9±5.8years, female:male 57:3 and disease duration in SP-APS versus sN-APS (10.17±4.9years versus 9.6±5.5years) respectively. Secondary APS was present in 16(53.3%) patients in group I compared to 3(10%) in group II (p<0.0001). The mean anti-AnxA5 IgG level was 10.7±5.6U/ml and IgM was 11.2±7.1U/ml and were comparable between the 2groups. The obstetric and thrombotic morbidity had no significant differences between SP and sN-APS. The IgG and IgM levels significantly correlated with the pregnancy morbidity, venous and arterial thrombosis events and showed reasonable sensitivities in their prediction (IgG:71.2%,72.8% and 75.8%; IgM: 68%,67.8% and 71.4% respectively) and specificities (IgG:75.9%,77.8% and 81.5%; IgM: 70.9%,73.1% and 73.7% respectively). Conclusion: anti-annexinA5 antibodies are promising for detecting obstetric and thrombotic morbidity in both SP- and sN-APS patients.