Incidence of infection is inversely related to steady-state (trough) serum IgG level in studies of subcutaneous IgG in PIDD.

Results from seven studies of four subcutaneous IgG preparations in patients with primary immune deficiencies show that the incidence of infection is inversely related to the steady-state IgG level. Maintaining higher IgG levels may be beneficial, and no given level is necessarily adequate for all patients.