Patient-reported outcomes with subcutaneous immunoglobulin in chronic inflammatory demyelinating polyneuropathy: the PATH study

Background and purpose: Chronic inflammatory demyelinating polyneuropathy (CIDP) causes weakness which adversely impacts function and quality of life (QOL). CIDP often requires long-term management with intravenous or subcutaneous immunoglobulin. The Polyneuropathy and Treatment with Hizentra® (PATH) study showed that subcutaneous immunoglobulin (SCIG) was efficacious in CIDP maintenance. Here, patient-reported outcomes in patients on SCIG are assessed. Methods: Subjects stabilized on intravenous immunoglobulin were randomly allocated to receive weekly 0.2 or 0.4 g/kg bodyweight of 20% SCIG (IgPro20) or placebo. Overall QOL/health status was assessed using the EuroQoL 5-Dimension (EQ-5D) health profile and visual analog scale, treatment satisfaction was assessed with the Treatment Satisfaction Questionnaire for Medicine (TSQM) and work-related impact was assessed with the Work Productivity and Activity Impairment Questionnaire for General Health (WPAI-GH). The EQ-5D health profile was assessed in terms of the percentage of subjects maintained or improved at week 25 of SCIG therapy on each of the EQ-5D domains versus baseline after intravenous immunoglobulin stabilization. TSQM and WPAI-GH were assessed by median score changes from baseline to week 25. Results: In total, 172 subjects were randomized to placebo (n = 57), 0.2 g/kg IgPro20 (n = 57) and 0.4 g/kg IgPro20 (n = 58). Significantly higher proportions of IgPro20-treated subjects improved/maintained their health status on the EQ-5D usual activities dimension, and in additional dimensions (mobility and pain/discomfort) in sensitivity analyses. TSQM and WPAI-GH scores were more stable with IgPro20 treatment compared with placebo. Conclusions: IgPro20 maintained or improved QOL in most subjects with CIDP, consistent with the PATH study findings that both IgPro20 doses were efficacious in maintaining CIDP.