Three possible explanations for seronegative APS are: 1) The diagnosis is incorrect (unlikely in all cases); 2) the previously positive tests have become negative over time (uncommon in my experience); or 3) new tests are needed.46
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Explore This IssueFebruary 2016
Perhaps the most potent reason for open-mindedness about seronegative APS comes from family studies. Some weeks ago, I saw a pair of identical twins—the first with classical seropositive APS, who later brought along her (absolutely) identical twin sister. The second twin had identical sets of symptoms, but unlike the first twin, she had negative aPL tests. Both patients responded to treatment.
Once a year, we hold a patients meeting at our hospital. At the last meeting, we arranged a simple anonymous questionnaire with two questions: Are you a patient with APS or a friend/spouse? Have you any close female relative (sister, mother, aunt) with autoimmune disease (i.e., lupus, RA, thyroid, multiple sclerosis, APS)? The result: Sixty percent of patients had a positive history of autoimmune illnesses in close relatives. Less than 20% of friends/spouses answered positive.
It may be that my own experience is skewed by referral bias from families of APS patients—but seropositive or not, most patients with seronegative APS respond just as well to treatment.
If some of these individuals in the family study did, in fact, have seronegative APS yet were potentially responsive to treatment, then the possibilities are intriguing. Perhaps a higher percentage of our migraine, young stroke, young angina patients might benefit from a closer look for more of the clues to APS—the dry Schirmer’s, the livedo, the family history of autoimmune disease—for example.
In many ways, it’s disappointing to confess that 30 years on, there are few new treatments. Introduction of the new oral anticoagulants in the treatment of APS has been predictably cautious, and it is too early to generalize.47
Statins, IVIG and hydroxychlorquine have been thrown into the mix and, of course, anti-B cell therapy has received favorable anecdotes. A recent study from Paris suggested that sirolimus, used in renal transplantation, might have a protective effect on aPL-induced vasculopathy.48
So in 2016, the current treatment of APS is still largely confined to aspirin, clopidogrel, heparin and warfarin.
Low-dose aspirin, despite its detractors, is, of course, first choice in many APS patients. However, clopidogrel remains a useful alternative in patients with gastritis or in asthmatics. But there is a third role for clopidogrel—important in the real world of practical medicine—that is, in those patients who, for whatever reason, have tried aspirin, without clear benefit.