Recurrent Thrombotic Events and Death Correlated with IgG Anticardiolipin Antibody Titer
ABSTRACT & COMMENTARY
Source: Levine SR, et al. IgG anticardiolipin antibody titer > 40 GPL and the risk of subsequent thrombo-occlusive events and death. Stroke 1997;28:1660-1665.
Anticardiolipin antibodies (aCL) have been incriminated as an independent risk factor for stroke (Antiphospholipid antibodies in stroke study [APASS] Group. Neurology 1993;43:2069-2073). The influence of aCL on recurrent stroke and other thrombotic events, however, is not certain, and a recent study did not show an increased risk of recurrent events in IgG aCL-positive patients (> 10 GPL) compared with aCL-negative patients (APASS Group. Neurology 1997; 47:91-94). Therefore, Levine and colleagues investigated the influence of a high aCL titer on recurrent thrombo-occlusive events.
One hundred thirty-two consecutive patients with stroke (n = 112) or TIA (n = 20) also with an IgG aCL titer of at least 10 GPL units at the time of their index event were followed prospectively. Patients were divided into two groups: those with aCL £ 40 GPL (n = 111; mean age, 63 ± 1 years; mean follow-up, 1.95 years) and those with aCL greater than 40 GPL (n = 21; mean age, 54 ± 2 years; mean follow-up, 1.5 years).
There was no difference between the groups for gender or prevalence of hypertension, diabetes mellitus, cigarette smoking, atrial fibrillation, or prior TIA.
The GPL greater than 40 group was younger (P = 0.05) but nevertheless had more prior strokes (9/21 [48%] vs 27/111 [20%]; P = 0.03). There were more recurrent thrombo-occlusive events and deaths in the GPL greater than 40 group (15/21 [71%] vs 51/111 [48%]; P = 0.03), and the median time to event in years was shorter (0.15 vs 0.61; P = 0.005). These data indicate that recurrent thrombo-occlusive events and death occur sooner and more frequently (see Table) in patients with an aCL titer greater than 40 GPL.
The increased frequency of recurrent thrombo-occlusions in the high titer aCL group did not reflect a failure to treat these high-risk patients; at the time of their subsequent events, 76% of the GPL greater than 40 group were on anticoagulants alone or in combination with antiplatelet agents or corticosteroids. Fourteen percent were on aspirin alone, and only 5% were on no medication.
Table
Frequency of Subsequent Events Compared with Baseline IgG aCL Titer
Event GPL < 40 (%) GPL > 0 (%) P
None 54 29 0.045
Stroke 9 14 0.434
TIA 5 29 0.003
Deep Vein Thrombosis 1 0
Myocardial Infarct 3 0
Death 15 19 0.608
COMMENTARY
This study group of only 21 patients with aCL greater than 40 GPL is too small for making generalizations about therapy. Larger controlled, randomized studies are needed to assess the effects of treatment on the natural history of this condition. The WARSS-APASS study currently underway (Cerebrovas Dis 1997;7:100-112) should provide clinicians with the information necessary to make firm treatment decisions. Until such time, it seems prudent to prescribe anticoagulants alone or in combination with aspirin to patients with aCL in high titer. The role of other factors in promoting hypercoagulatility such as the Factor V Leiden mutation (see Special Feature, this issue) and the presence of anti- phosphatidylserine antibodies (Triplell DA, et al. JAMA 1988;259:550-554) may also be important. jjc
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