Can Lupus Cause DVTs?
Yes, systemic lupus erythematosus (SLE) significantly increases the risk of deep vein thrombosis (DVT), primarily through the development of antiphospholipid antibodies (aPL), particularly lupus anticoagulant (LA), which confers approximately 6-fold increased risk for venous thromboembolism. 1
Mechanism and Risk Magnitude
The thrombotic risk in SLE is predominantly mediated through antiphospholipid antibodies, which develop in approximately 40% of SLE patients. 2 The risk stratification breaks down as follows:
- Lupus anticoagulant positive: 6-fold increased risk for DVT compared to LA-negative patients (odds ratio 5.61,95% CI 3.80-8.27) 1
- Anticardiolipin antibodies positive: 2-fold increased risk for DVT (odds ratio 2.17,95% CI 1.51-3.11) 1
- Recurrent thrombosis risk: LA increases recurrence risk 11.6-fold, while aCL increases it 3.9-fold 1
In prospective cohort data, SLE patients with mean RVVT (Russell viper venom time) greater than 37 seconds have an estimated 42% probability of developing DVT within 20 years of SLE diagnosis. 3 Each 5-second prolongation of RVVT increases immediate DVT risk by 34%. 3
Clinical Recognition and Testing
When evaluating SLE patients for thrombotic risk, you must:
- Test for complete antiphospholipid antibody profile: lupus anticoagulant (using dRVVT and sensitive aPTT), anticardiolipin IgG/IgM, and anti-β2-glycoprotein I IgG/IgM 4
- Confirm persistent positivity: Repeat all testing after 12 weeks, as transient positivity does not warrant treatment 4
- Recognize that LA is superior to aCL for risk prediction: LA demonstrates stronger and more consistent association with actual thrombotic events 3
Critical pitfall: An elevated aPTT in SLE may paradoxically indicate increased thrombotic risk rather than bleeding risk when due to lupus anticoagulant. 2 Specifically, aPTT values ≥37 seconds are significantly associated with thrombosis risk (p=0.003). 2
Management Based on Antibody Status
For Asymptomatic SLE Patients with Positive aPL:
- No anticoagulation is indicated for asymptomatic patients with antibodies alone 4
- Consider low-dose aspirin (75-100 mg daily) only if additional cardiovascular risk factors are present: hypertension, diabetes, smoking, family history of early cardiovascular disease 5, 4
- Absolutely avoid estrogen-containing contraceptives due to markedly increased thrombosis risk; recommend intrauterine devices or progestin-only options 4
For SLE Patients with Documented DVT and Positive aPL (Antiphospholipid Syndrome):
Initiate extended anticoagulation with vitamin K antagonist (warfarin) targeting INR 2.0-3.0 indefinitely. 5, 4 This represents standard-intensity anticoagulation for APS with venous thrombosis, based on strong evidence showing:
- Extended anticoagulation provides large benefit in reducing recurrent VTD 5
- Standard-intensity (INR 2.0-3.0) is preferred over high-intensity (INR 3.0-4.0) for venous thrombosis due to significant increase in major bleeding with high-intensity without proven additional benefit 5
Exception: For arterial thrombosis or stroke in SLE with APS, consider high-intensity anticoagulation (INR 3.0-4.0) due to particularly high recurrence risk in this population. 5
Additional Risk Factors Beyond Antiphospholipid Antibodies
While aPL is the primary driver, other SLE-related factors contribute:
- Lupus nephritis with proteinuria >2.5 g/day: Tends to increase thrombotic risk, though this did not reach statistical significance in all studies 2
- Inflammatory state: Higher C-reactive protein levels are associated with both DVT occurrence and LA positivity 6
- Protein S deficiency: Can occur in SLE patients even without antiphospholipid antibodies, though this is rare 7
Pregnancy Considerations
For SLE patients with positive aPL and history of pregnancy loss or thrombosis:
Use hydroxychloroquine plus low molecular weight heparin (LMWH) 40 mg daily plus low-dose aspirin throughout pregnancy. 5, 4 LMWH is superior to unfractionated heparin with better outcomes and no additional adverse effects. 5, 4
Avoid: Do not add glucocorticoids or intravenous immunoglobulin to heparin plus aspirin, as this significantly increases premature delivery without relevant benefits. 5
Temporal Risk Profile
The thrombotic risk in SLE with aPL persists throughout the disease course and does not diminish over time. 2 The event rate for thrombosis in aPL-positive SLE patients is 3.93 per 100 patient-years compared to 0.96 per 100 patient-years in aPL-negative patients. 2 This sustained risk necessitates ongoing vigilance and indefinite anticoagulation after a first thrombotic event.