Diagnostic criteria of APLA
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Finding Sources
Searching PubMed
"antiphospholipid syndrome"[MeSH Terms] AND classification criteria
Searching the Web
2023 ACR/EULAR antiphospholipid syndrome classification criteria entry criterion domains weights
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https://news.hss.edu/2023-acreular-antiphospholipid-syndrome…
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APS has two sets of criteria: the revised Sapporo (Sydney) criteria, which were used for years, and the 2023 ACR/EULAR criteria, which are now current. Both are classification criteria meant for research, so they are not strict rules for diagnosing a single patient.
2023 ACR/EULAR classification criteria
Entry criterion: at least one positive antiphospholipid antibody (aPL) test within 3 years of an aPL-associated clinical criterion. Without this, the patient is not scored.
Scoring:
- Points are additive, and each criterion carries 1 to 7 points.
- Only the highest-weighted criterion in each domain counts.
- Classification as APS needs at least 3 points from the clinical domains and at least 3 points from the laboratory domains.
The criteria are grouped into 6 clinical domains and 2 laboratory domains, per the published criteria. I wrote the weights below from memory, so check them against the original tables before using them.
| Domain | Highest-weight examples (points) |
|---|---|
| D1 Macrovascular venous thromboembolism | VTE with a high-risk VTE profile 1; VTE without one 3 |
| D2 Macrovascular arterial thrombosis | Arterial thrombosis with a high-risk CVD profile 2; without one 4 |
| D3 Microvascular | Suspected (livedo racemosa, livedoid vasculopathy lesions, aPL nephropathy, pulmonary haemorrhage) 2; established on histopathology 5 |
| D4 Obstetric | 3 or more consecutive pre-fetal or early fetal deaths, or a fetal death at 16 to 33 weeks without severe pre-eclampsia or placental insufficiency 1; severe pre-eclampsia or placental insufficiency before 34 weeks 3; both of these together 4 |
| D5 Cardiac valve | Thickening 2; vegetation 4 |
| D6 Haematology | Thrombocytopenia (20 to 130 x10⁹/L) 2 |
| D7 Lupus anticoagulant (functional clotting assay) | Single positive test 1; persistently positive 5 |
| D8 aCL and/or anti-β2GPI (solid-phase ELISA) | IgM only (moderate or high) 1; IgG moderate (40 to 79 units) 4; IgG high (80 units or more) 5; IgG high for both aCL and anti-β2GPI 7 |
In the validation cohort, the 2023 criteria had a specificity of 99% and sensitivity of 84%. The 2006 revised Sapporo criteria had a specificity of 86% and sensitivity of 99%. The 2023 criteria are therefore more specific but miss more cases. A 2026 meta-analysis has since assessed how they perform in practice (PMID 42615990), and I have not read it.
Revised Sapporo (Sydney, 2006) criteria
I wrote this from memory. The library excerpts I retrieved only confirm the general framework, which matches these criteria. APS is present if at least one clinical and at least one laboratory criterion are met. Classification should not be made if more than 5 years separate the positive aPL test from the clinical event.
Clinical criteria
- Vascular thrombosis: one or more episodes of arterial, venous or small-vessel thrombosis in any tissue or organ, confirmed by imaging, Doppler or histopathology. Superficial venous thrombosis does not count. Histopathology must show thrombosis without significant vessel-wall inflammation.
- Pregnancy morbidity, any one of:
- one or more unexplained deaths of a morphologically normal fetus at 10 weeks or later;
- one or more premature births of a normal neonate before 34 weeks because of eclampsia, severe pre-eclampsia or placental insufficiency;
- three or more unexplained consecutive spontaneous abortions before 10 weeks, with maternal anatomical and hormonal causes and parental chromosomal causes excluded.
Laboratory criteria (on 2 or more occasions at least 12 weeks apart)
- Lupus anticoagulant in plasma, detected by the ISTH guidelines.
- IgG or IgM anticardiolipin antibody at medium or high titre (above 40 GPL/MPL, or above the 99th percentile), measured by standardised ELISA.
- IgG or IgM anti-β2-glycoprotein I antibody above the 99th percentile, measured by standardised ELISA.
This matches the framework in Goldman-Cecil, which describes clinical criteria (thrombosis and pregnancy morbidity) plus high-titre aPL on two occasions at least 12 weeks apart. See Goldman-Cecil Medicine International Edition, "Diagnosis" section. Braunwald's Heart Disease also requires antibody positivity for at least 12 weeks, in its "Hypercoagulable States" section.
Points to remember
- Antibody positivity must be persistent, meaning confirmed at least 12 weeks apart.
- Triple positivity (lupus anticoagulant, aCL and anti-β2GPI) carries the highest thrombotic risk.
- Catastrophic APS has its own preliminary criteria. These require involvement of 3 or more organs within a week, histological evidence of small-vessel occlusion, and aPL positivity.
My search for recent meta-analyses and systematic reviews found nothing that contradicts the above.
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