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Antiphospholipid Syndrome (APS)

BSH Guidelines on the investigation and management of antiphospholipid syndrome. Published: Jul 2024.

Guidelines

  • All newly diagnosed SLESystemic lupus erythematosus
  • Unprovoked venous thrombosis
  • <50 y/o with arterial thrombosis with no other vascular risk factors
  • Obstetric APS clinical criteria (all the following assumes a morphologically normal fetus, i.e. in the absence of anatomical and chromosomal anomalies)
    • ≥3 consecutive unexplained miscarriages <10 weeks 
    • ≥1 unexplained fetal death ≥10 weeks 
    • ≥1 premature births <34 weeks due to severe pre-eclampsia / eclampsia / placental insufficiency 

 

BSH guidelines advise against testing for APL in those with VTE associated with a transient reversible major risk factor (e.g. surgery, immobilisation), or active cancer

  • At least 1 clinical event (objectively confirmed thrombotic event and/or pregnancy complication), AND
  • +ve antibodies (any of the following) on 2 occasions at least 12 weeks apart
    • Lupus anticoagulant
    • Anticardiolipin (IgM / IgG)
    • Anti-β2 glycoprotein-1 (IgM/IgG)

Laboratory changes (not part of the diagnostic criteria):
  • Thrombocytopaenia (mild to moderate)
  • Prolonged aPTT

Anticoagulation is generally NOT recommended for asymptomatic patients who have positive serology (suggesting APS) but no history of thrombosis or obstetric APS.

There are 2 main approaches
  • Primary prophylaxis: asymptomatic APL carrier without any history of thrombotic or obstetric events
  • Secondary prophylaixs: APL carriers with previous thrombotic or obstetric events
 

Consider low-dose aspirin in those with high thrombotic risk (e.g. triple-positive, high titer +ve, persistent lupus anticoagulant), weighing against bleeding risk
  • BSH endorse a personalised risk stratified approach instead of an universal recommendation

In short: warfain is the choice of anticoagulation in secondary prophylaxis.
 

1st line: indefinite anticoagulation with warfarin
  • Target INR 2.0-3.0
 
 

DOACs are not the choice of anticoagulation in APS (esp. triple +ve APS)

Arterial Thrombosis (Stroke)

1st line: warfarin

  • If warfarin contraindicated → dual antiplatelet therapy


If there are additional vascular risk factors (and no significant risk of bleeding): add an anti-platelet in addition to warfarin

Refer to specialist

If not on warfarin (e.g. DOAC or antiplatelet) → switch to warfarin

If already on warfarin:
  • 1st line: increase target INR to 3.0-4.0 or add antiplatelet while maintianing target INR 2.0-3.0
  • 2nd line: consider hydroxychloroquine
  • 3rd line: consider rituximab for refractory cases

Once the woman is pregnant
  • Stop warfarin
  • Give aspirin + LMWHLow molecular weight heparin (prophylactic dose) during pregnancy

Catastrophic APS should be suspected in a patient with APS presenting with multiple sites of thrombosis including microvascular thrombosis leading to organ failure
  • 1st line: triple therapy with therapeutic dose IV heparin + high-dose corticosteroid + IVIG and/or plasma exchange
  • 2nd line: retixumab and seek specialist input

References

Author: Adams Lau
Reviewer:
Last edited: 23/07/25