Clinical characteristics and risk factors of microvascular involvement in primary antiphospholipid syndrome: a longitudinal single-center study in China

Performance validation of the 2023 American College of Rheumatology/European League Against Rheumatism antiphospholipid syndrome classification criteria in an antiphospholipid syndrome cohort

BACKGROUND

The 2023 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) antiphospholipid syndrome (APS) classification criteria were developed with higher specificity but lower sensitivity compared with the 2006 Sydney revised classification criteria.

OBJECTIVES

To validate the performance of the 2023 ACR/EULAR APS classification criteria in a large Chinese APS cohort.

METHODS

This was a single-center cohort study. Inclusion criteria aligned with the entry criteria of 2023 criteria. APS classification by "expert consensus panel" served as the gold standard. Sensitivity and specificity were compared between the 2023 and 2006 criteria.

RESULTS

A total of 526 patients with a mean age of 38.55 ± 12.67 years were enrolled, of whom 366 (69.58%) were female and 182 (34.60%) had systemic lupus erythematosus (SLE). Among them, 407 (77.38%) patients were classified as APS by experts. The 2023 criteria demonstrated higher overall specificity than the 2006 criteria (0.983 vs 0.950), while sensitivity was relatively lower (0.818 vs 0.853). The sensitivity of the 2023 criteria improved for patients with SLE (0.860 vs 0.825), microvascular manifestations (0.867 vs 0.786), cardiac valve disease (0.903 vs 0.774), and thrombocytopenia (0.811 vs 0.790). Reduced sensitivity of the 2023 criteria was linked to the omission of certain microvascular manifestations, a stricter definition of pregnancy morbidity, and the exclusion of isolated thrombocytopenia and isolated IgM isotype antiphospholipid antibodies from meeting clinical and laboratory criteria, respectively.

CONCLUSION

The 2023 criteria offer higher overall specificity and improved sensitivity in specific patient subsets, such as those with SLE, microvascular manifestations, cardiac valve disease, and thrombocytopenia when compared with the 2006 criteria.

Serum Calprotectin as a Potential Predictor of Microvascular Manifestations in Patients with Antiphospholipid Syndrome

INTRODUCTION

Microvascular manifestations constitute a subtype of antiphospholipid syndrome, and those patients have relatively poor prognoses, so it is important to find markers for microvascular manifestations. This study was conducted to explore whether serum calprotectin could be a predictor of microvascular manifestations in antiphospholipid antibody (aPL)-positive patients.

METHODS

Consecutive patients with persistent aPL positivity referred to Peking Union Medical College Hospital and age- and sex-matched health controls (HCs) were included. Microvascular manifestations included antiphospholipid syndrome (APS) nephropathy, livedo reticularis, valvular lesions, non-stroke central nervous system manifestations, myocarditis, catastrophic APS, and other microvascular manifestations confirmed by pathology, imaging, or clinical diagnosis. Calprotectin was measured by an enzyme-linked immunosorbent assay (ELISA). The cutoff value was defined as mean + 2 standard deviations of HCs. Multivariable logistic regression analysis was used to analyze risk factors. Pearson correlation analysis was used to detect the correlation between calprotectin and other laboratory data.

RESULTS

Of the 466 patients included in the study, 281 (60.3%) patients met the 2006 Sydney Revised Classification Criteria; among the latter, 77.2% were patients with primary APS. The mean age was 39.10 ± 13.05 years old, and 77.0% were female. Thirty-eight age- and sex-matched HCs were included in the study. Serum calprotectin levels were increased in aPL-positive patients compared with HCs (649.66 ± 240.79 vs 484.62 ± 149.37 ng/ml, p < 0.001), and were increased in patients with microvascular manifestations compared with patients without (693.03 ± 271.90 vs 639.43 ± 232.06 ng/ml, p = 0.044). The cutoff value was 783.36 ng/ml. Ninety-three patients (20.0%) were positive for calprotectin. Calprotectin positivity was independently associated with microvascular manifestations (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.07-3.36) and platelet count (PLT) < 100 (OR 2.04, 95% CI 1.08-3.88). Age (OR 0.98, 95% CI 0.96-1.00), systemic lupus erythematosus (OR 2.08, 95% CI 1.15-3.75), calprotectin positivity (OR 1.83, 95% CI 1.02-3.26), hypertension (OR 2.73, 95% CI 1.36-5.45), hemolytic anemia (OR 2.66, 95% CI 1.13-6.23), and anti-β2GPI antibodies (OR 2.06, 95% CI 1.11-3.83) could independently predict microvascular manifestations in aPL-positive patients. Serum calprotectin negatively correlated with PLT (R = - 0.101, p = 0.031).

CONCLUSION

Serum calprotectin levels are increased in aPL-positive patients and could be a potential predictor of microvascular manifestations.

Clinical value of amyloid-beta1-40 as a marker of thrombo-inflammation in antiphospholipid syndrome

OBJECTIVE

Amyloid-beta1-40 (Aβ40) is a pro-inflammatory peptide under investigation as a novel biomarker of vascular inflammation, endothelial dysfunction and atherothrombosis in the general population. Herein we tested the hypothesis that Aβ40 is deregulated in APS, a systemic autoimmune disease characterized by a thrombo-inflammatory state.

METHODS

Between January 2016 and July 2017, we consecutively recruited 80 regularly followed thrombotic APS patients (44 primary, 36 SLE/APS) and 80 age- and sex-matched controls. Plasma Aβ40 levels were measured using ELISA and APS-related clinical and laboratory characteristics were recorded. The adjusted Global Anti-Phospholipid Syndrome Score (aGAPSS), a validated risk score in APS, was calculated as a comparator to Aβ40 performance to detect arterial thrombotic APS-related events.

RESULTS

Higher Aβ40 levels were significantly associated with the presence of APS [odds ratio (OR) 1.024 per 1 pg/ml (95% CI 1.007, 1.041)] after adjustment for cardiovascular risk factors (CVRFs), including smoking, arterial hypertension, dyslipidaemia and BMI, and for estimated glomerular filtration rate (eGFR). Among APS patients, increased high-sensitivity CRP (hs-CRP) serum levels was the only independent determinant of Aβ40 levels. Importantly, Aβ40 levels above the optimal receiver operating characteristics (ROC)-derived cut-off value were independently associated with recurrent arterial events [OR 4.93 (95% CI 1.31, 18.51)] after adjustment for age, sex, CVRFs, hs-CRP and high anti-β2 glycoprotein I IgG titres. Finally, by ROC curve analysis, Aβ40 provided incremental additive value over the aGAPSS by significantly improving its discrimination ability for recurrent arterial thromboses.

CONCLUSION

In APS, Aβ40 plasma levels are elevated and associated with an adverse thrombo-inflammatory profile. The pathophysiological and prognostic role of Aβ40 in APS merits further investigation.