The classification criteria for the antiphospholipid syndrome were initially formulated during 8th International Congress on antiphospholipid in Sapporo, Japan, in 1998 6. They formulated the clinical and laboratory criteria to diagnose the syndrome. A few adjustments to criteria has been made in 2004 at another workshop in Sydney, Australia during 11th International Congress on the antiphospholipid syndrome. One of the significant adjustment is the anti-?2 glycoprotein-I antibody being incorporated as the new entity in the laboratory criteria 1.They also introduce a concept of subclassification of antiphospholipid syndrome patients into four different categories of based on antiphospholid assay positivity. The investigators in this workshop encouraged to subclassify patients with positive laboratory assays that fulfill the criteria for antiphospholipid syndrome as multiple antiphospholipid positivity increase rate of thrombosis and severity of the disease.
They categorised the antiphospholipid antibody assay to category I, which is more than one laboratory criteria present with any combination, category IIa if lupus anticoagulant present alone, category IIb if anticardiolipin antibody present alone and category IIc if anti-?2 glycoprotein-I antibody present alone. Pengo et al 3 evaluated the combination of result in antiphospholipid antibodies test. Over 6 years in their study, 55% of the subjects that referred for antiphospholipid antibody detection had previous history of thrombotic event. They reviewed the patient’s record for the presence of the previous thromboembolic events or obstetric complication. They found that lupus anticoagulant and anti-?2 glycoprotein-I antibody were found to be independent risk factors for thrombosis related event. Their study showed that triple positivity resulted in a strong independent risk factor with odds ratio of 33.3 and confidence interval of 7.
0-157.6 compared to double positivity and other combinations. They concluded that complete antiphospholipid antibody profile can better determine patient risk of thrombosis as compared to single test. Different combinations of antiphospholipid antibodies associated with varying odds of thrombosis. Risk of thrombosis increase with additional antiphospholipid antibody 5. Neville et al (2003) found that with each additional antibody, the thrombotic event nearly doubles up the risk.
Their study also showed that different combination positivity of antibody gives different risk of thrombosis and clinical outcome. They demonstrated that higher titres of anticardiolipin IgG antibody is associated with an increased risk of both arterial and venous thrombotic event. Tincani et al 9 retrospectively evaluated the antiphospholipid profile in 175 patients and followed up them for 5.0 years. Their evaluation showed that the single positivity is not rare. They found that isolated lupus anticoagulant is more prevalent in vascular disease, while IgM subtype anti-?2 glycoprotein-I antibody is frequent in pure obstetrical APS.