Patients with laboratory criteria of anti-phospholipid syndrome and 'non-criteria' manifestations: a multicenter cohort.

OBJECTIVES:Patients with laboratory criteria for anti-phospholipid syndrome (APS) but presenting only 'non-criteria' clinical manifestations are scarcely characterized in the literature. We aimed to analyse a cohort of these patients regarding the most prevalent manifestations, antibody profile, and treatments, while establishing a comparison with definite APS patients. METHOD:A retrospective analysis was conducted of individuals fulfilling APS laboratory criteria assessed in two tertiary European hospitals between 2005 and 2020. Patients without clinical criteria but with non-criteria manifestations (termed 'clinical non-criteria') and age-/gender-matched controls were included. RESULTS:Altogether, 75 clinical non-criteria patients were analysed, with haematological (thrombocytopenia, haemolytic anaemia) and 'mild' neurological manifestations (white-matter lesions, migraine) as the most prevalent non-obstetric involvements. These patients displayed more thrombocytopenia [odds ratio (OR) = 3.6, 95% confidence interval (CI) 1.7-7.6; p = 0.001] than controls with APS, but severe manifestations, such as valvular heart disease (p < 0.001), livedoid vasculopathy, seizures, chorea, transverse myelitis, bone necrosis, and alveolar haemorrhage, occurred only in definite APS patients. Corticosteroids were required by 40% of patients with thrombocytopenia. Manifestations in anticoagulated patients included white-matter lesions, nephropathy, superficial vein thrombosis, amaurosis fugax, and livedoid vasculopathy. Suspicion of progression towards systemic lupus erythematosus (SLE) occurred in 19% of non-SLE individuals. CONCLUSION:'Clinical non-criteria' patients displayed significant treatment use, predominantly haematological involvement, and less severe manifestations than definite APS controls. Some patients may additionally progress to future SLE. The impact of certain manifestations flags them as potential future contributors to classifying individuals as definite APS.