Adequate IVIG dosing is associated with an improved long-term outcome in secondary immunodeficiency: A prospective, non-interventional study.

Objective: To assess the safety, tolerability, and effectiveness of the intravenous immunoglobulin (IVIG) Intratect 50 g/L in immunoglobulin replacement therapy (IgRT) in a prospective, large-scale non-interventional study (NIS). The analysis focused upon patients with secondary immunodeficiency (SID), the most frequent indication for IgRT in this NIS.

Materials and methods: Patients were enrolled at 123 centers in Germany. Each patient received IVIG as prescribed by the physician, guided by the Summary of Product Characteristics. Data were acquired from medical records and patients' questionnaires.

Results: In the NIS, 3,563 patients were documented. The main indication for IgRT was SID (73.2%), followed by primary immunodeficiency (14.7%), immune thrombocytopenia (5.8%), and other indications (6.2%). Among the SID patients, 52.9% were male, mean age was 66.5 years, and most (63.8%) were IVIG-naïve. Their annual infection rate improved from 3.7 before documentation in the NIS to 1.1 during the first year of the study. IgG trough plasma levels increased during treatment (> 6 g/L: 44.5% of SID patients at study entry and 64.8% in long-term treatment) and were associated with a trend toward reduced infection rate (p = 0.08). A 1-year infection analysis showed a significantly lower infection risk in the medium- and high-dose groups than in the low-dose group (p = 0.028 and p = 0.017, respectively). Patients' treatment satisfaction and quality of life improved from baseline. Adverse drug reactions (ADRs) in SID occurred at a low frequency with 0.8% at infusion level. On the patient level, ADRs occurred in 251 (15.3%) SID patients, with chills (7.4%) and pyrexia (0.9%) reported most frequently.

Conclusion: Effectiveness, safety, and quality of life confirmed the positive benefit-risk profile of IgRT. Higher IVIG dosages per body weight led to higher IgG plasma trough levels, in turn leading to reduced infection rates. Obese patients may need body-weight-adjusted treatment to reduce the risk of infection.