Difference between primary and secondary Antiphospholipid Antibody Syndrome
PAPS, also termed as Hughes syndrome, occurs in 0.5% of the population. Females outnumber males 3.5:1 and the mean age is 34 years. It is defined as the presence of aPL abs in the setting of thrombosis without another associated disease. Thrombocytopenia, recurrent miscarriage, and/or livedo reticularis may be present. Virtually any venous or arterial site has been affected by thrombosis from these antibodies. In a large group of patients with aPL abs-related thrombosis, approximately two out of three thrombotic events are venous, whereas one out of three are arterial. The site of initial thrombosis often predicts the site of recurrent thrombosis (arterial 90%, venous 75%) in a given individual. Typical thrombotic events include DVT, pulmonary embolus, transient ischemic attack, stroke, and myocardial infarction (11% patients). aPL abs account for approximately 20% of women who experience recurrent miscarriages/placental ischemic complications, 20% of unprovoked DVTs, and 20% of young patients (age, <50 years) who get strokes (“ one-in-five rule ”). Notably up to 10% of patients with PAPS will evolve into systemic lupus erythematosus (SLE) within 10 years.
SAPS: approximately 50% of patients with APS have an associated rheumatic disease, most commonly SLE. Alternatively, up to 40% to 50% of SLE patients have aPL abs and the presence of aPL abs is on the list of criteria for the diagnosis of SLE (under the “Immunologic” criterion). In the group with both SLE and aPL abs, up to a half will subsequently develop a thrombotic event (SAPS). Prospectively, 3% to 7% of SLE patients per year who have aPL abs will experience a new thrombotic event. Other diseases and medications can be associated with production of aPL abs