Title: Antiphospholipid Syndrome
Session Type: Abstract Submissions (ACR)
Background/Purpose: Whether aspirin is needed in patients with antiphospholipid antibodies (aPL+) for prevention of a first thrombotic event is controversial. The aim of this metaanalysis was to determine whether aspirin had a protective effect in aPL+ patients with no history of thrombosis.
Methods: Both observational (either prospective or retrospective) and interventional studies were selected if they assessed the incidence of the first thrombosis in patients with aPL, either treated with aspirin or not, were included. Data sources were MEDLINE, Embase, Cochrane Library, hand search, contact with investigators, and reference lists of studies, without language restrictions. Data on study and patient characteristics, risk estimates, and study quality were independently extracted by 2 investigators. Pooled effect estimates were obtained by using random-effect models according to the DerSimonian and Laird method.
Results: Of 342 identified abstracts, 9 primary studies (8 observational and 1 interventional) met inclusion criteria, including 1136 aPL patients and 133 thrombotic events. Compared with aPL+ patients without aspirin (n=556), the overall pooled odds ratio for the risk of first thrombosis in aPL+ patients treated with aspirin (n=580) was 0.48 (95%CI: 0.24 to 0.93), with significant heterogeneity across studies (I²=53%, p=0.03). Subgroup analysis according to the type of study suggested a protective effect of aspirin when considering only retrospective (OR: 0.25 [0.15-0.43]) but not prospective (OR: 0.84 [0.46-1.54]) studies. Subgroup analysis according to the type of thrombotic event suggested a protective effect of aspirin when considering only arterial (OR: 0.48 [0.28-0.83]) but not venous (OR: 0.52 [0.24-1.14]) thrombosis.
Conclusion: This metaanalysis suggests that aspirin has a protective effect for the risk of first thrombosis among aPL+ patients. Significant heterogeneity was found across included studies, with subgroup analyses showing a protective effect in retrospective but not in prospective studies, as well as for arterial but not venous first thrombotic events. A collaborative metaanalysis of individual patient data is currently underway to clarify these findings at patient level by taking into account the various pathogenic backgrounds as well as potential confounding factors.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-of-aspirin-for-the-prevention-of-the-first-thrombo-embolic-events-in-patients-with-antiphospholipid-antibodies-a-metanalysis-of-literature-data/