Do ethnoracial differences exist among antiphospholipid antibody-positive patients with no other systemic autoimmune diseases: results from the APS ACTION registry

Objective: The APS ACTION Registry was created to study long-term outcomes in persistently antiphospholipid antibody (aPL)-positive patients. The objectives of this study were to examine the ethnoracial differences in clinical and laboratory characteristics of aPL-positive patients with no other systemic autoimmune rheumatic diseases (SARDs). Methods: A web-based data capture system stores patient demographics and aPL-related medical history. Inclusion criteria are positive aPL results, based on the revised Sapporo APS classification criteria, tested at least twice within one year prior to enrollment. For this cross-sectional analysis of the baseline data, demographic, clinical, and laboratory characteristics of registry patients were analyzed based on self-reported ethnorace (White, Latin American Mestizo [LAM], Asian, and Black). Results: 728 patients with no history of other SARD (78% with APS classification) were included in the analysis. The ethnoracial distribution was 516 (78%) White, 82 (12%) LAM, 49 (7%) Asian, and 13 (2%) Black. Based on ethnoracial comparisons: (a) there were less females among White patients; (b) livedo reticularis/racemosa was more frequent in LAM patients; and (c) triple aPL positivity was more frequent in Whites, while isolated lupus anticoagulant positivity was more common in LAM patients. Conclusion: In our international registry of persistently aPL-positive patients with or without APS classification, Blacks were the least frequently (2%) reported ethnoracial group. No major ethnoracial differences were found in the aPL-related clinical manifestations. Our analysis highlights the need for further investigation into the genetic and social determinants impacting the clinical and serologic phenotypes of aPL-positive patients across diverse populations.