Update on antiphospholipid syndrome.

Revised criteria for the antiphospholipid syndrome were published in 2006. Major changes from the 1999 criteria are an increase in the time between two laboratory studies required for diagnosis from 6 to 12 weeks, the acceptance of antibody to beta2 glycoprotein I as a criterion, the exclusion of older age persons, and the acknowledgment of several associated findings such as livedo, heart valve disease, and antibody to prothrombin. New concepts of pathogenesis now invoke complement activation and participation of the innate immune system upstream to thrombosis. Warfarin remains the treatment of choice for patients who have suffered thrombosis, but antiplatelet agents and heparin are options. Target INR is 2.0-3.0. Treatment is potentially life-long, though options for withdrawal of treatment are under investigation.