Profile and clinical relevance of non-criteria antiphospholipid antibodies in patients diagnosed with or highly suspected of APS

Abstract Objective This study investigates the positivity and relevance of non-criteria aPLs with clinical phenotypes in patients highly suspected of or diagnosed with APS. Methods Outpatient cases were included from a prospectively maintained database, and patients were grouped into APS (n = 168), seronegative APS (SNAPS, n = 9), those meeting the diagnostic criteria for clinical events without laboratory results (only-event, n = 15), those that had aPL positivity without clinical manifestations (asymptomatic APA, n = 39), and healthy controls (n = 88). Criteria aPL results and APS-related clinical features were extracted. Sixteen non-criteria aPLs were tested and analysed. Results LA, aCL and anti-β2 glycoprotein-I were positive in 84.5%, 61.3% and 74.4% of APS patients, and 61.5%, 59.0% and 74.4% of asymptomatic APA patients, respectively. In patients negative for criteria serological tests, 23 out of 24 were positive for at least one non-criteria aPL. Triple-positive patients also had significantly higher tests of some aPLs in comparison with other groups. Stroke was associated with anti-phosphatidyl-inositol (aPI) IgG and anti-phosphatidyl-glycerol (aPG) IgG. Late embryonic loss correlated with aPI IgM, and premature birth/eclampsia was associated with aPI IgG and aPG IgG. There were also positive associations between heart valve lesions and anti-phosphatidylserine–prothrombin (aPS/PT) IgM, APS nephropathy and anti-phosphatidyl-choline IgG or aPS/PT IgG, and livedo reticularis and anti-phosphatidyl-ethanolamine IgM. Conclusion The prevalence of non-criteria aPLs differed from diagnostic biomarkers in patients diagnosed with or suspected of APS. Detection of aPLs provided additive value in the evaluation of APS-related clinical manifestations.