Nine-test panel has superior sensitivity to detect antiphospholipid antibody syndrome in patients with or without SLE

Assessment of the 2023 ACR/EULAR antiphospholipid syndrome classification criteria in a Chinese cohort: Impact on clinical practice

OBJECTIVES

To evaluate the effectiveness of the 2023 ACR/EULAR criteria for antiphospholipid syndrome (APS) in a Chinese cohort, and compare them with the Sapporo and revised Sapporo criteria.

METHODS

A cohort comprising 436 patients diagnosed with APS and 514 control subjects was enrolled, including 83 with seronegative APS and 86 classified as antiphospholipid antibody (aPL) carriers. We assessed IgG and IgM anticardiolipin antibodies (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies using ELISA, along with a systematic collection of lupus anticoagulant data. Subsequently, we compared the sensitivity and specificity across the three classification criteria.

RESULTS

The 2023 ACR/EULAR criteria exhibited improved specificity at 98 %, surpassing the revised Sapporo (90 %) and original Sapporo (91 %) criteria. However, this came with decreased sensitivity at 82 %, in contrast to higher sensitivities in the revised Sapporo (98 %) and Sapporo (91 %) criteria. Examining individual components sheds light on the scoring system's rationale within the new criteria. The inclusion of microvascular thrombosis, cardiac valve disease, and thrombocytopenia improved the identification of nine patients previously classified as "probable APS". Insufficient scoring in 78 previously diagnosed APS individuals was linked to traditional risk factor evaluations for thrombotic events, the emphasis on determining whether obstetric events are linked to severe preeclampsia (PEC) or placental insufficiency (PI), and the lower scores assigned to IgM aCL and/or aβ2GPI antibody. Seronegative APS remained a challenge, as non-criteria aPL and other methods were not included.

CONCLUSIONS

The new criteria presented notable advancements in specificity. This study provides detailed insights into the strengths and possible challenges of the 2023 ACR/EULAR criteria, enhancing our understanding of their impact on clinical practice.

Anti-Phospholipid Antibodies in COVID-19 Are Different From Those Detectable in the Anti-Phospholipid Syndrome

Background

Critically ill patients with coronavirus disease 2019 (COVID-19) have a profound hypercoagulable state and often develop coagulopathy which leads to organ failure and death. Because of a prolonged activated partial-thromboplastin time (aPTT), a relationship with anti-phospholipid antibodies (aPLs) has been proposed, but results are controversial. Functional assays for aPL (i.e., lupus anticoagulant) can be influenced by concomitant anticoagulation and/or high levels of C reactive protein. The presence of anti-cardiolipin (aCL), anti-beta2-glycoprotein I (anti-β2GPI), and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies was not investigated systematically. Epitope specificity of anti-β2GPI antibodies was not reported.

Objective

To evaluate the prevalence and the clinical association of aPL in a large cohort of COVID-19 patients, and to characterize the epitope specificity of anti-β2GPI antibodies.

Methods

ELISA and chemiluminescence assays were used to test 122 sera of patients suffering from severe COVID-19. Of them, 16 displayed major thrombotic events.

Results

Anti-β2GPI IgG/IgA/IgM was the most frequent in 15.6/6.6/9.0% of patients, while aCL IgG/IgM was detected in 5.7/6.6% by ELISA. Comparable values were found by chemiluminescence. aPS/PT IgG/IgM were detectable in 2.5 and 9.8% by ELISA. No association between thrombosis and aPL was found. Reactivity against domain 1 and 4-5 of β2GPI was limited to 3/58 (5.2%) tested sera for each domain and did not correlate with aCL/anti-β2GPI nor with thrombosis.

Conclusions

aPL show a low prevalence in COVID-19 patients and are not associated with major thrombotic events. aPL in COVID-19 patients are mainly directed against β2GPI but display an epitope specificity different from antibodies in antiphospholipid syndrome.