Objective: The impact of reducing immunoglobulin dosage while switching from intravenous to subcutaneous replacement therapy was evaluated.
Methods: Sixty-five patients with primary hypogammaglobulinemia on stable intravenous replacement therapy were included in a monocentric longitudinal trial. IgG trough levels were measured at baseline and during 1 year following the switch to the subcutaneous route.
Results: Mean IgG trough level after 12 months of subcutaneous therapy was increased by 5.4 percent (8.37-8.82 g/l, p=0.3), while immunoglobulin dosage had been reduced by 28.3% (151-108 mg/kg/week, p<0.0001). For the patients with the lowest serum IgG level upon intravenous infusions, serum IgG level rose by 37 percent (5.33-7.33 g/l, p=0.003), while mean immunoglobulin dosage was reduced by 36 percent (170-109 mg/kg/week, p=0.04).
Conclusion: The present study shows that sustained serum IgG levels can be achieved after switching towards subcutaneous replacement despite using reduced immunoglobulin doses.