[Clinical characteristics of 37 antiphospholipid syndrome patients complicated by autoimmune hemolytic anemia]

Objective: We sought to investigate the clinical characteristics and risk factors of antiphospholipid syndrome (APS) complicated by autoimmune hemolytic anemia (AIHA). Methods: Retrospective anaysis.Three hundred fifteen consecutive patients with APS were enrolled at the Department of Rheumatology of Peking Union Medical College Hospital between May 2017 to May 2021, and their clinical manifestations[including initial symptoms, time interval between APS onset and diagnosis, systemic lupus erythematosus(SLE), thrombotic events, obstetric morbidity, and extra-criteria manifestations] and laboratory test results[including blood routine, antiphospholipid antibodies(aPLs), blood lipid profile, homocysteine, anti-nuclear antibody profile, immunoglobulin levels, and complement levels] were collected. Then, univariate and multivariate logistic regression analyses were performed. Clinical features and risk factors were analyzed using univariable and multivariable logistic regression analysis. Results: Among 315 APS patients, 37 cases (11.7%) were complicated by AIHA, and AIHA was the first manifestation or co-occurrence. The median time interval between APS onset and diagnosis was 12 months. The proportion of SLE in APS patients combined with AIHA was higher than that in APS patients without AIHA[62.2%(23/37) vs. 19.4%(54/278), P<0.001]. There was no significant difference in the proportions of thrombosis and pregnancy morbidity between the two groups. In terms of extra-criteria manifestations, APS patients with AIHA had a significantly (P<0.05) greater risk of thrombocytopenia (OR=6.19, 95%CI 2.81-13.65) and higher proportions of hypocomplementemia, a positive lupus anticoagulant (LA) result, double aPLs positivity[i.e., any two of the following antibodies were positive: LA, anticardilolipin antibody(aCL), and anti-β2 glycoprotein Ⅰ(β2GPⅠ)], and triple aPLs positivity (i.e., LA, aCL, and anti-β2GPⅠ antibodies were all positive). Multivariate logistic regression analysis showed that SLE (OR=3.46,95%CI 1.60-7.48), thrombocytopenia (OR=2.56,95%CI 1.15-5.67), and hypocomplementemia (OR=4.29,95%CI 2.03-9.04) were independent risk factors for the complication of APS. In the primary APS subgroup, multivariate logistic regression analysis showed that livedo reticularis (OR=10.51,95%CI 1.06-103.78), thrombocytopenia (OR=3.77, 95%CI 1.23-11.57), and hypocomplementemia (OR=5.92,95%CI 1.95-17.95) were independent risk factors for the complication of APS. Conclusions: AIHA is not rare in APS patients; moreover, it occurs more frequently in APS secondary to SLE and is more likely to present with a variety of extra-criteria manifestations. Patients with AIHA should be promptly tested for antiphospholipid antibody profiles and alerted to the possibility of thrombotic events.