Can a patient be diagnosed with both antiphospholipid antibody syndrome (APS) and systemic lupus erythematosus (SLE)?

Diagnosing Antiphospholipid Syndrome and Systemic Lupus Erythematosus Concurrently

Yes, a patient can be diagnosed with both antiphospholipid antibody syndrome (APS) and systemic lupus erythematosus (SLE) simultaneously, as they commonly co-occur and represent distinct but related autoimmune conditions. 1, 2

Relationship Between APS and SLE

• APS can occur as a primary condition (primary APS) or in association with other autoimmune diseases, with SLE being the most common associated disorder (secondary APS) 1, 2
• Approximately 40% of patients with SLE have antiphospholipid antibodies (aPL), though less than 40% of these patients initially present with thrombotic events 3
• Up to 50-70% of aPL-positive SLE patients may develop clinical APS during a 20-year follow-up period 3

Diagnostic Considerations

• The diagnosis of both conditions requires meeting separate classification criteria:

  • SLE diagnosis is based on ACR/SLICC classification criteria 3
  • APS diagnosis requires one clinical criterion (vascular thrombosis or pregnancy morbidity) and one laboratory criterion (persistent presence of aPL) 4

• Laboratory testing for APS in SLE patients should include:

  • Lupus anticoagulant (LA) testing using both activated partial thromboplastin time (APTT) and dilute Russell's viper venom time (dRVVT) 4
  • Anticardiolipin antibodies (aCL) IgG and IgM 4
  • Anti-beta2 glycoprotein I antibodies (aβ2GPI) IgG and IgM 4
  • Two consecutive positive tests at least 12 weeks apart are required to confirm persistent positivity 4

Clinical Implications of Dual Diagnosis

• SLE patients with concurrent APS often display a distinct clinical profile including:

  • More frequent arthralgias and arthritis 1
  • Higher rates of autoimmune hemolytic anemia 1
  • Increased incidence of livedo reticularis 1
  • Higher risk of epilepsy and other neuropsychiatric manifestations 1, 3
  • Greater likelihood of glomerular thrombosis and myocardial infarction 1
  • More rapid progression to chronic kidney disease 3

• Triple aPL positivity (LA, aCL, and aβ2GPI) in SLE patients carries the highest thrombotic risk 4

Diagnostic Challenges

• Overlapping clinical features can complicate diagnosis, as several manifestations appear in both classification criteria 3
• Kidney involvement requires careful differentiation between lupus nephritis and APS-associated nephropathy (APSN) 3
• Renal biopsy is essential for differential diagnosis, with APSN found in 11.4-39.5% of SLE patients with aPL, and in 67-100% of SLE-APS patients who undergo biopsy 3

Treatment Implications

• The combination of SLE and APS appears to confer worse prognosis than either condition alone 5
• Management requires accurate stratification of vascular risk factors 1
• Primary prophylaxis with low-dose aspirin and hydroxychloroquine should be considered in SLE patients with positive aPL but no thrombotic history 1
• For secondary prophylaxis (after thrombotic events), anticoagulation with vitamin K antagonists is typically required 1
• In high-risk situations (surgery, immobilization, puerperium), prophylaxis should be intensified with low molecular weight heparin 1
• Anticoagulation may be more appropriate than escalating immunosuppression in some cases of SLE with APS 5

Important Caveats

• Diagnosis of APS in SLE patients is often underestimated due to overlapping symptoms 3
• All SLE patients should be routinely screened for aPL antibodies 3
• The presence of aPL antibodies in SLE patients significantly worsens disease course and increases mortality risk 3
• Anti-phosphatidylserine/prothrombin antibodies (aPS/PT) are more prevalent in patients with APS associated with autoimmune diseases compared to primary APS, further supporting the link between APS and SLE 6