Patients with primary immunodeficiency receiving subcutaneous immune globulin Hizentra maintain health‐related quality of life and treatment satisfaction in a multicentre extension study of efficacy, tolerability and safety

Objective  The purpose of the study was to evaluate the maintenance and sustainability of health‐related quality of life (HRQoL) in patients being treated long‐term for primary immunodeficiency (PID) with subcutaneous infusions of Hizentra, a new human immunoglobulin G containing proline. Methods  Twenty‐one patients who completed a 12‐month Phase III open‐label, single‐arm, prospective, multicentre study of the efficacy, tolerability, safety and pharmacokinetics of Hizentra were offered the opportunity to participate in an extension phase. HRQoL and treatment satisfaction were measured every 12–60 weeks using the Medical Outcomes Study Short‐Form 36 (SF‐36v2), EuroQol 5D (EQ‐5D) Index Score, Life Quality Index (LQI), Treatment Satisfaction Questionnaire for Medication Short Form (TSQMv1.4), and a disease‐specific Immunoglobulin G Therapy Specific Questionnaire (IgGTSQ). Due to the small sample size, results were compared to 95% confidence intervals (95% CIs). Key findings  Sixteen patients with available HRQoL data were included in the analysis. All SF‐36v2 domains had corresponding 95% CIs that contained the US norm across visits with the exception of the General Health (GH) domain, which was lower (GH US norm, 70.85; GH upper confidence limit ranged from 64.12 to 69.43 across visits). Although the SF‐36v2 minimum important differences pre‐specified for comparison fell within the 95% CIs around the change from baseline in many cases, the 95% CIs also included zero, indicating stability. The EQ‐5D Index Score was stable, and fell within the 95% CI of the US Norm (0.87) at each visit. The LQI reflected high quality of life due to immunoglobulin treatment; mean domain scores were between 77.3 and 92.3 across visits. The TSQM showed high levels of satisfaction following treatment; mean domain scores were between 68.4 and 93.8 across visits. The IgGTSQ indicated that patients maintained positive feelings about their current therapy (mean ≥82.2 across visits) as well as when receiving treatment at home (mean ≥86.9 across visits). Conclusion  Patients continuing on Hizentra over a 96‐week extension study maintained HRQoL and overall treatment satisfaction.