AB0473 HYPOGAMMAGLOBULINEMIA AND INFECTIONS IN RHEUMATOLOGIC PATIENTS TREATED WITH RITUXIMAB
Authors: Andres Fierro, Mariano Andres, Jenny de la Torre-Aboki, Paloma Vela-Casasempere, Maria Paz Martínez-Vidal
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Treatment with rituximab (RTX) for rheumatologic diseases may produce hypogammaglobulinemia (hypoglb) (1,2), and that way increase the risk to acquire certain infections (3,4). There are no stablished guides to evaluate and treat hypoglb in these patients. In our hospital, the percentage of patients who develop hypoglb and severe infections is unknown. <h3>Objectives</h3> To analyse the effect of RTX on immunoglobulin (Ig) levels and to evaluate the severe infections and hepatitis B reactivations that could be related to this treatment. <h3>Methods</h3> This is a descriptive, retrospective study of patients followed up in the Rheumatology Unit of the Alicante General University Hospital (HGUA) who had received at least one course of RTX. Clinical characteristics and laboratory parameters were obtained from the electronic charts: type of disease, posology and total amount of RTX, Ig levels before and after treatment with RTX, the concomitant treatment with disease-modifying drugs (DMDs), hepatitis B virus's (HBV) reactivations and infections that required hospitalization. Hypoglb was assessed when IgG&lt; 750 mg/dL, and severe hypoglb if IgG &lt;450 mg/dl. The association of hypoglb with disease and treatment's aspects was studied by t-Student, U-Mann-Whitney and Chi-2. Multiple logistic regression was conducted to study the independent risk factors associated with hypoglb. The study was approved by the Hospital Ethics Committee. <h3>Results</h3> Finally 106 patients were included, 85 women (80.2%) and 21 men (19.8%). The more frequent conditions were rheumatoid arthritis (47.2%), Sjögren syndrome (16%), Systemic Lupus Eritematosus (13.2%), vasculitis (6.6%) and other connective tissue diseases (10.4%). Characteristics of the sample are shown in table 1. A correct follow up of the Ig levels during the treatment was shown to be undergone in 87.7% of the cases. It was found that 35.8% of the patients presented hypoglb and 13,2% presented severe infections after receiving RTX. No HBV reactivations were found. Among the patients with hypoglb, 78.9% received concomitant treatment with other immunosuppressants (methotrexate 23.6%, leflunomide 23.6%). Hypoglb was more frequent in rheumatoid arthritis (44%), lupus (42.8%) and vasculitis (28.6%). Through simple logistic regression hypoglb during treatment was associated with the presence of previous hypoglb (p=0.025), higher doses received (p=0.01) and longer treatment (p=0.003). In the multiple logistic regression, only low levels of Ig before treatment turned out to be an independent risk factor for hypoglb during treatment (OR 6.86; IC 1.25-37.57). The IgM and IgA levels, but no the IgG levels were significantly lower in patients who has severe infections. <h3>Conclusion</h3> Hypogammaglobulinemia happens in a third of the patients who receive RTX, especially in those who have low previous IgG levels; therefore a follow up during the treatment should be encouraged. Low IgM and IgA levels during the treatment could also be associated with severe infections. <h3>References</h3> [1] Christou EAA. Int Rev Immunol. 2017;3:352. [2] Roberts DM. Journal of Autoimmunity 2015;57:60 [3] Gea-Banacloche, JC; Seminars in Hematology 2010;47:187. [4] Salliot C.Ann Rheum Dis 2009;68:25 <h3>Disclosure of Interests</h3> Andres Fierro: None declared, Mariano Andres: None declared, Jenny de la Torre-Aboki: None declared, Paloma Vela-Casasempere Grant/research support from: UCB, Abbvie, Pfizer, Roche, Bristol-Myer-Squibb (another research, not BIOBADASER related), Consultant for: UCB, Lilly, Pfizer, Roche, Bristol-Myer-Squibb, Speakers bureau: Roche, UCB, MSD, Pfizer, GSK, BMS, Lilly, Maria Paz Martínez-Vidal: None declared