In reply: ‘Non-criteria’ antiphospholipid antibodies and thrombosis (February 2018)

We appreciate the response of Drs. Maharaj, Chang, and Shaikh. Antiphospholipid antibody testing and the diagnosis of antiphospholipid antibody syndrome are quite complex. We recognize that there is controversy with regard to the role of antiphosphatidylserine (aPS) antibodies, antiprothrombin antibodies, (aPT-A), and antibodies to the antiphosphatidylserine-prothrombin complex (aPS/PT).

In the systematic review cited, the authors concluded that measurement of aPS/ PT may be helpful in determining the thrombotic risk in a subset of patients with prior thrombosis and systemic lupus erythematosus (SLE).¹ However, the majority of the studies included in the systematic review enrolled patients with antiphospholipid antibody syndrome and SLE. Our patient did not have SLE. Additionally, most of the studies were small. Therefore, the independent association between aPS/PT and thrombosis in patients without known SLE or previously known antiphospholipid antibody syndrome is challenging to infer on the basis of available data.¹

At our institution, we do not routinely test for these “non-criteria” antibodies as part of our evaluation of suspected antiphospholipid antibody syndrome. However, we agree that this is an area that warrants further investigation. There is a need for prospective trials or, more likely, longitudinal observational studies to further delineate the association of aPT-A, aPS, or aPS/PT with clinical features of antiphospholipid antibody syndrome.²

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