DefinitionAntiphospholipid antibody syndrome (APS) is anautoantibody-mediated acquired thrombophiliacharacterized by recurrent arterial or venous thrombosisand/or pregnancy morbidity in the presence ofautoantibodies against phospholipid (PL)-binding plasmaproteins, mainly a plasma apolipoprotein known as 2glycoprotein I (2GPI) and prothrombin. Another group ofantibodies termed lupus anticoagulant (LA) prolongclotting times in vitro; this prolongation is not corrected byadding normal plasma to the detection system. APS mayoccur alone (primary), or in association with any otherautoimmune disease (secondary).
EpidemiologyAnti-PL (aPL)-binding plasma protein antibodies occur in 1–5% ofgeneral population. Their prevalence increases with age; however,it is questionable whether they induce thrombotic events in elderlyindividuals. One-third of patients with systemic lupuserythematosus (SLE) possess these antibodies while theirprevalence in other autoimmune connective tissue disorders suchas systemic sclerosis (scleroderma), Sjögrens syndrome,dermatomyositis, rheumatoid arthritis, and early undifferentiatedconnective tissue disease, ranges from 6% to 15%. One-third ofaPL positive individuals experience thrombotic events orpregnancy morbidity.
Clinical Features of Antiphospholipid Antibody Syndrome• Deep vein thrombosis• Stroke• Migraine• Arthralgia• Preeclampsia• Early fetal loss (<10 weeks)• Thrombocytopenia
Clinical criteria(1) vascular thrombosis defined as one or more clinical episodes of arterial, venous, or small vessel thrombosis in any tissue or organ.(2) Pregnancy morbidity, defined as (a) one or more unexplained deaths of a morphologically normal fetus at or beyond the tenth week of gestation, or (b) one or more premature births of a morphologically normal neonate before the thirty-fourth week of gestation because of eclampsia, severe preeclampsia, or placental insufficiency; or (c) three or more unexplained consecutive spontaneous abortions before the 10th week of gestation.
Laboratory criteria(1)LA(2)Anticardiolipin (aCL)(3)Anti-2GPI antibodies, at intermediate or high titers on two occasions, 12 weeks apart.
TreatmentAPS patients should be placed on warfarin for life aimingto achieve an international normalized ratio (INR) rangingfrom 2.5 to 3.5, alone or in combination with 80 mg ofaspirin daily. Pregnancy morbidity is prevented by acombination of heparin with aspirin 80 mg daily.Intravenous immunoglobulin (IVIg) 400 mg/kg qd for 5days may also prevent abortions, while glucocorticoidsare ineffective. Evidence-based treatment of patients withaPL in the absence of any clinical event is not available;however, aspirin 80 mg daily protects patients with SLEpositive for aPL antibodies from developing thromboticevents.