Background/Purpose:

There is limited data regarding the long-term risk of developing a first-time thrombotic event and prophylactic benefits of aspirin use in asymptomatic aPL-positive carriers. This study was designed to evaluate the long-term risk of thrombosis and the risk factors associated with the development of a first thrombotic event in asymptomatic aPL-positive carriers. We also aimed to assess the preventive effect of aspirin use.

Methods:

One hundred three of 575 patients, who consecutively tested positive in a core laboratory for aCL and/or LA in 2 determinations between 1995 and 2000, were included in a first analysis published in 2008. Patients have been evaluated for thrombosis occurrence and prophylactic benefits of aspirin use during the first study period that ended in 2005. Exclusion criteria included history of previous thrombosis and long-term anticoagulation treatment. In this study, we added data on patient’s follow-up during the ten-year period following the first analysis, except for 5 patients who were lost to follow-up. Clinical and biological data were retrospectively collected until time of first thrombotic event or through July 2014 for patients who remained asymptomatic. Survival analyses were performed using Kaplan-Meier method. Cox proportional hazards analysis examined factors associated with thrombosis-free survival.

Results:

Ninety-eight patients were followed during a median follow-up period of 156 months (72-204). Population was composed of 13 men and 85 women. Median age was 40.5 years (28-55). Forty-two had SLE. Sixty-six were treated prophylactically with aspirin. Median treatment duration was 130 months (60-192). At onset, 59 patients had LA, 72 aCL and 39 anti-β2 Glycoprotein 1 antibodies (aβ2GP1) IgG or IgM, 20 were triple positive. At the end of follow-up, 22 were triple positive. A first thrombotic event occurred in 28 patients. The 15-year risk of a first thrombosis was 30%.

 The univariate analysis showed that neither gender, SLE status nor biological aPL profile at onset were associated with risk of thrombosis. aCL, LA and aβ2GP1 persistence through follow-up, alone or triple positivity of aPL, were significantly associated with a higher risk of thrombosis. Conversely, aPL disappearance was associated with a lower risk of thrombosis. Despite insignificant association between aspirin prescription at diagnosis and thrombotic risk, a longer period of prescribed aspirin was associated with a lower risk of thrombosis. 

In the multivariate analysis, aPL triple positivity persistence through follow-up remained the only predictive factor significantly and independently associated with the risk of thrombosis (HR 2.81; 95% CI: 1.30-6.08, p=0.009).

Conclusion:

The risk of developing a first-time thrombosis in asymptomatic aPL-positive carriers is significant and persistent over time. Triple positive-carriers appear to be exposed to a considerable risk of thrombosis and may justify a close follow-up. Prophylactic effects of aspirin against first thrombotic event seem to be attractive but more data are needed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/triple-positivity-of-antiphospholipid-antibody-as-the-main-thrombotic-factor-in-a-long-term-follow-up-study-of-98-asymptomatic-apl-positive-carriers/