Blood Is Thicker Than Water: Updates on the ACR/EULAR Antiphospholipid Syndrome Classification Criteria

With this in mind, the new APS criteria create four macrovascular domains: 1) VTE with high VTE risk profile, 2) VTE without high VTE risk profile, 3) arterial thrombosis with high cardiovascular disease (CVD) risk profile, and 4) arterial thrombosis without high CVD risk profile. Dr. Zuily provided examples of major VTE risk factors, such as major trauma or high risk surgery, as well as minor risk factors, including the presence of a central venous catheter or hormone replacement therapy. He also defined high CVD risk factors, such as severe arterial hypertension and chronic kidney disease, in addition to moderate CVD risk factors, including active current tobacco smoking and obesity.

Dr. Zuily also discussed how the new criteria describe microvascular domains of APS in much greater detail than the Revised Sapporo criteria. For instance, the microvascular domains include livedo racemosa, livedoid vasculopathy, acute or chronic antiphospholipid nephropathy and pulmonary hemorrhage. For each of these findings, a distinction is made between suspected and established microvascular disease; for example, livedoid vasculopathy based on physical exam alone would be suspected disease, whereas exam combined with pathology findings of this entity would be established disease.

Several other innovations from the new APS criteria were discussed as well. Dr. Zuily pointed out that pregnancy loss at less than 10 weeks is relatively common and not specific for APS, but is more frequently seen in APS when it is associated with severe pre-eclampsia or placental insufficiency. Thus, the new classification criteria obstetric domain includes pre-eclampsia and/or placental insufficiency with severe features at less than 34 weeks’ gestation with or without fetal death.

Regarding additional clinical domains, cardiac valve pathology, such as thickening or vegetations, and thrombocytopenia have been added as well, given that these can all be features of APS. For the laboratory domains, new thresholds have been designated for anticardiolipin and beta-2 glycoprotein I antibodies depending on whether it is the IgG or IgM antibody being identified, and, for the lupus anticoagulant, a single (one-time) positive test is included as a criterion as it may be relevant in cases where repeat testing is not possible (i.e., the patient is on anticoagulation).

Caveats

Dr. Erkan

The final speaker in the session, Doruk Erkan, MD, MPH, attending physician, Hospital for Special Surgery, New York City, and professor of medicine, Weill Cornell Medicine, New York City, presented the draft criteria in full and made several editorial comments. The first comment was that the entry criteria require at least one documented clinical criterion plus a positive antiphospholipid test, such as lupus anticoagulant or moderate to high titers of anticardiolipin or beta-2 glycoprotein I IgG or IgM within three years of the clinical criterion.