{
  "abstract": "Objectives Rituximab (RTX) is an established therapy for refractory Systemic Lupus Erythematosus (SLE), but its use raises concerns about infection risk and hypogammaglobulinemia. Data on the infectious risk associated with RTX in SLE remain limited. This study aimed to evaluate the incidence and characteristics of severe infections in SLE patients treated with RTX.Methods This single-center cohort study included consecutive SLE patients who fulfilled the 2019 ACR/EULAR classification criteria and received RTX therapy. Severe infections were defined as those requiring hospitalization. Cumulative incidence and 95% confidence intervals (CI) were estimated using Kaplan–Meier survival analysis, and risk factors were assessed using Cox proportional hazards model. Demographic, clinical, immunologic, and therapeutic variables were considered.Results A total of 46 patients were included. Median age at diagnosis was 32 (25–39) years and disease duration of 37 (9–160) months prior to RTX initiation. Median follow-up after RTX was 68 (30–110) months. Most patients (61%) received concomitant immunosuppressive therapy, most frequently azathioprine (n=10), mycophenolate mofetil (n=8), or methotrexate (n=5). RTX was administered in a median of three cycles (2–6) over 18 months.During follow-up, 11 patients (24%) experienced 14 severe infections, corresponding to an incidence rate of 2.7 per 100 patient-years (95%CI 1.5–4.9). The most frequent infections were lower respiratory tract infections (n=4), urinary tract infections (n=3), and opportunistic infections (n=3, including two cytomegalovirus and one Salmonella spp. infection). The infection rate was markedly higher during the first year of RTX therapy, 21.4 per 100 patient-years (95% CI 10.7–42.9), compared with subsequent years (0.82 per 100 patient-years; 95% CI 0.36–2.5). Persistent hypogammaglobulinemia developed in 4% of patients. Two deaths occurred during follow-up, one due to lung cancer and one to infectious endocarditis. Independent predictors of severe infection were older age at diagnosis (HR 1.06, 95% CI 1.01–1.11, p=0.014) and low serum IgM within six months of RTX initiation (HR 6.35, 95% CI 1.42–28.5, p=0.016).Abstract PO:03:079 Figure 1Conclusions Severe infections were relatively uncommon in RTX-treated SLE, occurring predominantly in the first year of therapy. Chronic hypogammaglobulinemia was rare. Older age and low IgM emerged as independent predictors of infection risk, highlighting the need for careful monitoring of immunoglobulin levels during early treatment.",
  "authors": [
    {
      "affiliations": [
        "Immune Response and Vascular Disease Group, NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal",
        "Internal Medicine Department, Hospital Santa Maria, Lisbon, Portugal"
      ],
      "name": "Ana Mafalda Abrantes"
    },
    {
      "affiliations": [
        "Immune Response and Vascular Disease Group, NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal",
        "Systemic Immunomediated Diseases Unit, Hospital Prof. Doutor Fernando Fonseca, Amadora, Portugal"
      ],
      "name": "João Fernandes Serodio"
    },
    {
      "affiliations": [
        "Internal Medicine Department, Hospital São Sebastião, Santa Maria Feira, Portugal"
      ],
      "name": "Cátia Henriques"
    },
    {
      "affiliations": [
        "Immune Response and Vascular Disease Group, NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal",
        "Systemic Immunomediated Diseases Unit, Hospital Prof. Doutor Fernando Fonseca, Amadora, Portugal"
      ],
      "name": "Marta Carapeto Amaral"
    },
    {
      "affiliations": [
        "Immune Response and Vascular Disease Group, NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal",
        "Systemic Immunomediated Diseases Unit, Hospital Prof. Doutor Fernando Fonseca, Amadora, Portugal"
      ],
      "name": "Catarina Favas"
    },
    {
      "affiliations": [
        "Immune Response and Vascular Disease Group, NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal",
        "Systemic Immunomediated Diseases Unit, Hospital Prof. Doutor Fernando Fonseca, Amadora, Portugal"
      ],
      "name": "José Delgado Alves"
    }
  ],
  "title": "PO:03:079 Severe infections in systemic lupus erythematosus patients treated with rituximab: a single-center cohort study",
  "uid": "3ec2b38b-038f-522c-81d6-ea4abfeb232d"
}