Initiation of immunoglobulin therapy by subcutaneous administration in immunodeficiency patients naive to replacement therapy

BACKGROUND Patients with immunodeficiency diseases require lifelong treatment with immunoglobulin (Ig), yet few studies have vetted dosing strategies and effectiveness of Ig in older patient populations. Patients requiring subcutaneous (SC) Ig (SCIG) typically start with intravenous dosing before transitioning to SCIG weekly maintenance. In this retrospective review, we investigated an alternate strategy with higher initial SC doses among an older patient population with antibody deficiency syndromes. FINDINGS Records of 13 patients (mean age, 70 years) with antibody deficiencies who were naive to treatment with Ig were assessed. SCIG (Vivaglobin® [Immune Globulin Subcutaneous (Human), 16% Liquid] or Hizentra® [Immune Globulin Subcutaneous (Human), 20% Liquid]) was given twice weekly (100 mg/kg) for 2 weeks, followed by weekly (100 mg/kg) administration The mean pretreatment IgG level was 460 mg/dL; at 1, 3, and 6 months after SCIG initiation, mean IgG serum levels were 852, 907, and 943 mg/dL, respectively. Maintenance doses were unchanged during 6 months of follow-up. All patients remain on SCIG (median, 44 months). One patient developed sepsis/cholangitis unrelated to treatment 3 months after starting SCIG; no other serious bacterial infections were reported. CONCLUSIONS Initiation of SCIG by doubling the maintenance dose over 2 weeks may be a well-tolerated and effective option for patients with antibody deficiencies requiring Ig replacement, especially among older patients.