Background/Purpose: Thrombotic events (TE) are common in patients with SLE. Antiphospholipid antibodies (aPL) are a risk factor for incident and recurrent TE; therefore these patients receive long term anticoagulation for secondary prophylaxis. SLE patients with negative aPL antibodies are also at increased risk of TE; however, the recurrence rate, type of TE, factors associated, and the optimal duration of anticoagulation is unknown. In the general population, the recurrence-rate of thrombosis at 5 years is 12.4%. The objective of this study is to determine the recurrence-rate of TE, type, and risk-factors associated in SLE patients negative for aPL antibodies according to the Sapporo Criteria. 

Methods: The study was conducted within a prospective cohort. We identified patients with negative aPL (aCL and LA), who developed  incident arterial (ATE) or venous thrombosis (VTE) during follow-up in the cohort, after 1990 when the aPL antibodies tests became widely available, and enrolled into the cohort within 5 years of SLE diagnosis. The demographic (age, ethnicity), clinical (disease duration, ACR criteria, SLE manifestations), autoantibodies (anti-dsDNA, anti-ENA, C₃, C₄), disease activity (SLEDAI-2K), disease damage (SDI) and treatment (prednisone, immunosuppressants, antimalarials, low-dose aspirin), type of TE (ATE, VTE), and traditional TE risk-factors (smoking, cholesterol levels, hypertension) were assessed. Main outcomes were the recurrence rate of TE, type, and variables associated. 

Results: Forty SLE patients with negative aPL antibodies and incident TE were identified; they developed 14 ATE, and 29 VTE (3 patients had both ATE and VTE).  Nine (22.5%) patients developed a second TE during 207.31 patient-years (py) of follow-up; recurrence-rate 4.3 TE per 100 py. The first event in seven patients was VTE, one ATE, and one both VTE/ATE. Eight recurrent events were VTE, and only one ATE; the concordance of vascular bed involved between both TE was total. Most (78%) recurrent events developed within 15 months after the first TE. Although non-statistically significant, patients with recurrent TE were female (100% vs. 81%), had younger age (25.8 ± 9.9 vs. 34.2 ± 14.9 yrs.), were predominantly of African ancestry (50% vs 16%), and had shorter SLE duration at first TE (1.7 ± 1.5 vs. 4.8 ± 4.9 years) in comparison to patients with no recurrence. No differences in other clinical manifestations, activity, damage or treatment were observed. The prevalence of traditional thrombotic risk-factors was also similar between groups. 

Conclusion: The recurrence-rate of TE is elevated among SLE patients with negative aPL antibodies, particularly VTE. Most recurrent TE happened within 15 months from the first TE and were seen in young female patients, with short disease duration and predominantly in those with African ancestry. If these results are confirmed in larger studies, they should be useful to better stratify recurrence risk and define the length of anticoagulation in this SLE subpopulation.

« Back to 2015 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/recurrence-rate-of-thrombotic-events-in-sle-patients-negative-for-antiphospholipid-antibodies/