[The clinical manifestations and risk factors in primary antiphospholipid syndrome with thrombocytopenia].

Objectives: To cross-sectionally analyze the clinical characteristics of primary antiphospholipid syndrome (PAPS) patients with thrombocytopenia, risk factors associated with thrombocytopenia, and risk of symptom recurrence in these patients. Methods: The inpatients with PAPS were retrospectively analyzed in Peking Union Medical College Hospital from 2009 to 2019. Using the collected clinical and laboratory data, the clinical characteristics and risk of symptom recurrence in the PAPS patients with thrombocytopenia were compared with those in the PAPS patients with normal platelet counts. Univariate and multivariate logistic regression analyses were performed to screen the risk factors for thrombocytopenia. Results: In this study, 127 patients with PAPS were enrolled, of which 36 (28.3% ) had thrombocytopenia, with a median age of 38 years, and 63.9% were female. In the thrombocytopenia group, the average platelet count was (58.9±27.0) ×10(9)/L, and the prevalence of thrombosis and morbid pregnancy was not significantly different from that in the normal platelet group. However, the thrombocytopenia group had higher incidence rate of autoimmune hemolytic anemia (19.4% vs 3.3% ) , livedo reticularis (16.7% vs 3.3% ) , chronic kidney disease (25% vs 8.8% ) and antiphospholipid antibodies triple positiveness (61.1% vs 37.4% ) , lower complement levels (C3 of 0.87 g/L vs 1.07 g/L, C4 of 0.12 g/L vs 0.18 g/L, P<0.05) , and higher adjusted Global APS Score (median score of 13 vs 9, P=0.037) than the normal platelet group. In multivariate logistic regression analysis, hypocomplementemia (OR value 5.032, 95% CI 3.118-22.095) is an independent risk factor for thrombocytopenia. Conclusions: In patients with PAPS, thrombocytopenia is mostly mild to moderate. Hypocomplementemia may be the independent risk factor for thrombocytopenia in PAPS patients. The PAPS patients with thrombocytopenia may have a higher risk of symptom recurrence.