Identifying phenotypes of patients with antiphospholipid antibodies: results from a cluster analysis in a large cohort of patients

• Published in: Rheumatology (Oxford, England) Vol. 60; no. 3; pp. 1106 - 1113
• Main Authors: Sciascia, Savino, Radin, Massimo, Cecchi, Irene, Bertolaccini, Maria Laura, Bertero, Maria Tiziana, Rubini, Elena, Vaccarino, Antonella, Bazzan, Mario, Giachino, Osvaldo, Baldovino, Simone, Rossi, Daniela, Mengozzi, Giulio, Roccatello, Dario
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 02-03-2021
• Subjects: antiphospholipid syndrome; systemic lupus erythematosus; thrombosis; antiphospholipid antibodies
• ISSN: 1462-0324; 1462-0332
• DOI: 10.1093/rheumatology/kez596

Abstract
Objectives
To identify the aggregation of patients with aPL into different subgroups sharing common features in terms of clinical and laboratory phenotypes.
Methods
We applied a hierarchical cluster analysis from the multiple correspondence analysis to determine subgroups of patients according to clinical and laboratory characteristics in a cohort of subjects with confirmed aPL positivity who presented to our outpatient clinics from 2006 to 2018.
Results
A total of 486 patients [403 women; age 41.7 years (26)] were included, resulting in five clusters. Cluster 1 (n= 150) presented with thrombotic events (65.3% with venous thrombosis), with triple aPL positivity found in 34.7% of them (the highest rate among the different clusters). All the patients from cluster 2 (n = 91) had a confirmed diagnosis of SLE and the highest rate of anti-dsDNA positivity (91.7%). Cluster 3 included 79 women with pregnancy morbidity. Triple positivity was present in 3.8%, significantly lower when compared with Cluster 1 (34.7% versus 3.8%, P <0.01). Cluster 4 included 67 patients, 28 (41.8%) of whom with APS. Thrombotic events were observed in 23.9% patients. Cluster 4 had the highest rate of cytopenia, with thrombocytopenia as high 41.8% with no anti-dsDNA antibodies. Cluster 5 included 94 asymptomatic aPL carriers.
Conclusion
While clusters 1, 2, 3 and 5 corresponded to well-known entities, cluster 4 might represent a bridging condition between pure primary APS and defined SLE, with lower thrombotic risk when compared with primary APS but higher general features such as ANA and cytopenia (mainly thrombocytopenia).