Abstract
BackgroundSeronegative antiphospholipid syndrome (SN-APS) is often defined as the presence of APS criteria manifestations, negative antiphospholipid antibodies (aPL), and coexistence of APS non-criteria manifestations. Nevertheless, the impact of these non-criteria features is still unclear. On a different note, the relevance of one single aPL positive determination in patients with APS manifestations is another domain with limited evidence. We aim to compare the course of SN-APS and single-positive aPL (SP-aPL) patients with that of individuals with APS manifestations without non-criteria features/aPL positivity (controls).MethodsRetrospective analysis of patients with thrombosis/obstetric morbidity assessed in two European hospitals between 2005 and 2020. Patients were divided into SN-APS, SP-aPL, and control groups. Clinical characteristics, comorbidities, and therapies were compared.ResultsA total of 82 patients were included in the SN-APS group, 88 in the SP-aPL group, and 185 in the control group. In Cox regression model, SN-APS displayed more thrombosis recurrence than controls (HR 3.8, 95% CI 2.2–6.5, p < 0.001) even when adjusting for the presence of hereditary thrombophilia, systemic lupus erythematosus, or contraceptive hormonal treatment. In SP-aPL, the difference in thrombosis recurrence did not reach statistical significance (p = 0.078). Indefinite anticoagulation (p < 0.001 and p = 0.008, respectively) and vitamin K antagonist (VKA) use (p < 0.001 in both cases) were more common in SN-APS/SP-aPL.ConclusionSN-APS displayed more thrombosis recurrence, indefinite anticoagulation, and VKA use than controls without non-criteria manifestations. The presence of such features in patients with thrombosis and negative aPL may negatively impact their clinical course.
Highlights
The classification criteria for definite antiphospholipid syndrome (APS) [1] are currently facing a revision, with new criteria under development [2]
Study design Patient selection We retrospectively reviewed the clinical records of patients assessed in the Autoimmune Diseases, Internal Medicine, Thrombophilia and Obstetrics Departments of two tertiary European hospitals—University Hospital Center of São João (Oporto, Portugal) and Hospital Clínic of Barcelona (Barcelona, Catalonia, Spain)—between January 2005 and December 2020, selecting all those with thrombosis and/or obstetric morbidity fulfilling the APS clinical classification criteria [1], but not fulfilling laboratory criteria
A significantly lower frequency of males was observed in the Seronegative antiphospholipid syndrome (SN-APS) group in comparison to the control group (OR = 0.5, 95% confidence intervals (CI) = 0.3–0.9, p = 0.022), with no difference (p = 0.120) when adjusting for the presence of obstetric patients in each group; on the other hand, no significant differences on gender distribution were found between the single-positive aPL (SP-aPL) and control groups (p = 0.107)
Summary
The classification criteria for definite antiphospholipid syndrome (APS) [1] are currently facing a revision, with new criteria under development [2]. Other definitions have been presented, and in a previous publication, we address the different descriptions present in the literature [3], with most publications [5,6,7] including the presence of APS manifestations and aPL negativity, and the presence of non-criteria manifestations (i.e., clinical manifestations fairly prevalent in APS patients but not included in the classification criteria). The latter comprise both non-obstetric (e.g., thrombocytopenia, valvular heart disease, livedo reticularis) and obstetric manifestations (e.g., two spontaneous abortions, late pregnancy morbidity) [8]. We aim to compare the course of SN-APS and single-positive aPL (SP-aPL) patients with that of individuals with APS manifesta‐ tions without non-criteria features/aPL positivity (controls)
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