Is It Time To Reconfigure Lupus Anticoagulant Panels?.

Traditional lupus anticoagulant (LAC) panels are designed to test the presence/absence of antiphospholipid antibodies (APA). These usually include testing for a LAC with clot based assays (dRVV, Hex PL, aPTT) or with the tissue thromboplastin inhibition assay (TTI) and ELISA assays for anticardiolipin antibodies (ACA). It is now recognized that antibodies to a phospholipid binding protein, beta-2-GPI are important in the autoimmune form of the antiphospholipid syndrome (aPls). Moreover, some patients (pts.) may only be positive in this latter testing and have what is termed sero-negative aPls. The present study is a retrospective medical record review methodology to analyze the results of APA tests in 258 consecutive pts. referred to the PI at the Hemostasis & Thrombosis Clinic at the Institute For Transfusion Medicine. Inclusion criteria were any pt. who had a lupus panel and anti-beta-2-GPI (IgG, IgM and IgA) testing performed. Exclusion criteria were any pts. who did not have this testing or pts. with positive results which were not repeated > 2 months later. The cohort consisted of 258 pts (69M:189F) with a median age of 48 (range=13–85). Of these pts., 35 (13%) were referred for risk assessment, 133 (52%) for arterial or venous thrombosis, 62 (24%) for neurologic reasons, and 27 (11%) for other reasons. Patients on no anticoagulation (OAC) were considered to be LAC+, if any of the clot based assays was repeatedly positive, did not correct on a mix, and shortened with the additon of phospholipid. OAC pts. with positive ELISA assays were considered to have a LAC if the dRVV was positive on a mixing study and/or if the Hex PL test was positive. OAC pts. with only evidence for a LAC, were taken off OAC and then studied. ELISA assays were considered to be positive if low titer positive or higher, e.g. ≥ 3 STD above the mean. Positive results were found in 59/258 (22.8%) of these pts. The antibody results are listed in the table below in the pts. referred for risk assessment and in the pts. referred with events. The results are listed in categories of APA positivity.

These results indicate that one-third of the pts. with phospholipid antibodies were sero-negative, e.g. negative in the presently constructed panels but positive for anti-beta-2-GPI antibodies. Skeptism exists about the meaning of isolated anti-beta-2GPI positivity. Of the pts. with only + beta-2-GPI antibodies, one male was asymptomatic (5%). The remaining pts. in this group were females. Ten/twenty-one (48%) of the pts. with isolated beta-2-GPI positivity were referred for neurologic reasons. These consisted of TIA’s in 6, complex migraines with TIA’s and acral cyanosis (1), recurrent fetal loss and TIA’s in 3. Eight pts. (38%) had recurrent venous thromboembolism and 2 (9%) had both arterial and venous thromboembolism. We suggest that it may be time to consider constructing LAC screening panels containing tests for both LAC and anti-beta-2-GPI antibodies (all three isotypes) as sero-negative APls appear to be fairly common in females referred for thrombophilic testing.