Methods: Patients who had previously received 10% IVIG completed 6 infusion visits using 5% IVIG. At each visit, ADRs and data from patient diaries were recorded. Immune-biomarkers, including C1-INH/C1-INHF levels, were also evaluated.
Results: Fifteen subjects completed the study; 12 with CVID and 3 with hypogammaglobulinemia. Switching to 5% IVIG reduced the number of ADRs by 40%. There were also reductions in mean fatigue index, headache score, and neuropathic pain score from IVIG 10% to 5%. Patients experienced an increase in physical function, greater energy, less fatigue, higher emotional rating and an increase in social function. The mean C1-INH|C1-INHF on 10% decreased from 31 to 13 mg/dL (normal 21-29mg/dL)|91% to 59% (normal >67%) while on 5 % the mean C1-INH|C1-INHF decreased from 27 to 21mg/dL|89% -76%.
Conclusions: This study demonstrated that C1-INH/C1-INHF level changes play a role in the incidence of ADRs for IVIG therapy; and a subset of patients may be more susceptible to C1-INH/C1-INHF downregulation by IVIG 10%. Further studies are necessary.