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, singlearm, 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.