Health-related quality of life, treatment satisfaction and clinical aspects of patients with primary antibody deficiency receiving subcutaneous IgG self-infusions at home

Abstract: Patients with primary antibody deficiencies (PAD) are unable to produce sufficient amounts of antibodies and are therefore susceptible to severe bacterial infections. The standard therapy has been intravenous infusions of immunoglobulin G (IVIG) every 2-4 weeks. While this treatment has proved to be effective and safe, it is cumbersome for patients: it may be difficult to find venous access, and they have to visit the hospital regularly to deal with repeated IVIG infusions. IgG serum levels are not stable between infusions. Rapid subcutaneous immunoglobulin G (SCIG) self-infusions provide a suitable alternative that has an excellent safety and efficacy profile, is easy, and can be performed at home. As IVIG and SCIG replacement therapies are both equally effective, patient-reported outcomes (PRO) such as health-related quality of life (HRQL), and treatment satisfaction (TS) may be used as criteria for an evidence-based choice of treatment alternatives. Studies investigating the infection experience of paediatric and adult PAD patients, as well as data addressing the HRQL and TS of PAD patients, have been rare or even non-existent. Some questionnaires used to capture PRO data have never been used or validated in PAD patients. For the present project two prospective multinational studies were conducted in PAD patients, one in Europe and Brazil, and another one in the USA and Canada, with the following objectives: to study the safety and efficacy of rapid SCIG self-infusions at home (adults, children); to compare IVIG replacement therapy in the hospital or at home and SCIG self-infusions at home with regard to PRO measures (HRQL: SF-36 for adults, CHQPF50 for children; TS: LQI for adults and children); and to examine validation aspects of the instruments used to assess HRQL and TS. Once they had switched from IVIG to SCIG therapy, IgG levels increased in children and remained constant in adults. Only one serious infection (pneumonia) occurred, and the rate of systemic adverse reactions, mainly mild, amounted to 1% of the infusions. Twenty-eight percent of the infusions were followed by mostly mild, local, transient tissue reactions which required no treatment and declined over time. Parents reported significant improvements related to their children's social functioning and health, the parents' own life situation and the way the family functioned. There was significant improvement on the SF-36 Mental Health and Social Functioning scales in the European study, and on the Role Physical, General Health and Health Transition scales in the North American study. The Vitality scale improved significantly in both studies. For patients on IVIG at hospital at enrolment, SCIG home therapy resulted in greater independence, with less disruption of daily activities, less impact on school, work and social activities, freedom to travel, better therapy convenience, comfort, treatment flexibility and pleasantness of treatment atmosphere. Patients who had received IVIG at home at study enrolment reported improved health status. Almost all adult and paediatric patients/caregivers preferred home treatment, and a great majority, even those who had been satisfied with IVIG at home, preferred subcutaneous self-infusions. The LQI could be broken down into four factors, relating to treatment interference with daily life activities, therapy-related problems, therapy setting and costs. To conclude, the studies have shown that SCIG self-infusions at home are not only effective and safe, but adults, children and their caregivers appreciate this method. HRQL is significantly improved and a marked improvement in TS gives the patients and their families greater independence and flexibility.