PF708 THE IMPACT OF ANTIPHOSPHOLIPID ANTIBODIES (APL) ON OUTCOMES OF PATIENTS WITH IMMUNE THROMBOCYTOPENIA AND AUTOIMMUNE HEMOLYTIC ANEMIA TREATED WITH SPLENECTOMY

Background: Antiphospholipid antibodies (aPL) are present in up to 40% of patients with autoimmune cytopenias. There is limited information about their clinical significance. Splenectomy is a second line therapy in both Immune Thrombocytopenia (ITP) and Autoimmune Hemolytic Anemia (AIHA) with high response rates and durable remissions. There is no information about the impact of aPL in patients treated with splenectomy and there are concerns about lower response rates and a higher incidence of thrombosis. Aims: Define the impact of aPL on the safety and efficacy of splenectomy for the treatment of ITP or AIHA. Methods: We performed a case‐control study, including patients with either ITP or AHAI treated with splenectomy between 2000 and 2018. The cases were patients with moderate to high aPL titers in two measurements with 12 weeks apart. They could have a clinical criterion of antiphospholipid syndrome (APS) but patients with another autoimmune disease were excluded. The control group included patients with IT or AIHA with a negative determination of aPL. Cases and controls were paired by age, diagnosis (IT or AIHA), and date of splenectomy. Results: We included 68 patients (34 in each group): ITP 53% and AIHA 47%. Most patients were female (78%) with a median age of 37 years (19 to 63). Among the cases (aPL patients), 41% had triple antibody positivity and 62% a lupus anticoagulant phenomenon (LA). Before splenectomy, aPL patients have received more steroid cycles (p = 0.05) and more lines of therapy other than steroids (p = 0.02) in comparison with controls. The time between diagnosis and splenectomy was longer in aPL patients (54 vs. 18 months, p = 0.02). At 30 days, complete response (CR) rates for aPL patients and controls were 65% and 79% respectively (p = 0.27). We identify as factors associated with lower CR rate: AIHA diagnosis, thrombotic APS, positive anti‐beta2‐glycoprotein, aPL with triple antibody positivity and a more than one line of treatment. On multivariate analysis, only AIHA remained significant (OR 0.07, IC 95% 0.0–0.4, p  < 0.001). Regarding splenectomy, most were laparoscopic (88%). There were no differences in medical complications (35% vs. 23% p = 0.42) however, patients with aPL had a higher incidence of early infections (21 vs. 3%, p = 0.05). On multivariate analysis, patients with thrombotic APS (OR 6.9, IC 95% 1.3–34.8, p = 0.01) and an open splenectomy (OR 6.1, IC 95% 1.1–32.7 p = 0.03) had a higher risk of medical complications, whereas women had a lower risk (OR 0.2, IC 95% 0.0–0.9 p = 0.04). Median follow‐up was 52 months vs. 41 months (p = 0.14) for aPL patients and controls. At last follow‐up 44% vs. 38% required a new treatment for ITP/AIHA (p = 0.8). There was no difference in treatment‐free survival among both groups (log rank, p = 0.83). The incidence of long term infections and thrombosis during follow‐up was similar between groups (21% vs 6% p = 0.07 and 15% vs 9% p = 0.7, respectively). Long term Infections were associated with a shorter treatment‐free survival period (HR = 5.3, IC 95% 1.9–14.1 p  < 0.00). Summary/Conclusion: Although patients with aPL (with or without APS) are taken to splenectomy later and with more previous treatment lines, the response rate and treatment‐free survival are similar to those of patients without aPL. The incidence of thrombosis is the same between groups, but there was a higher incidence of infections in aPL patients. The latter can be related to the more intensive immunosuppressive treatment before splenectomy. Patients with thrombotic APS had more medical complications and a trend of lower response rates that must be further explored.