A Systematic Review and Meta-regression Analysis on the Impact of Increasing IgG Trough Level on Infection Rates in Primary Immunodeficiency Patients on Intravenous IgG Therapy.

Abstract

We conducted a systematic review and meta-regression analysis to evaluate the impact of increasing immunoglobulin G (IgG) trough levels on the clinical outcomes in patients with PID receiving intravenous immunoglobulin G (IVIG) treatment. Systematic search was conducted in PubMed and Cochrane. Other relevant articles were searched by reviewing the references of the reviewed article. All clinical trials with documented IgG trough levels and clinical outcome of interest in patients receiving IVIG treatment were eligible to be included in this review. Meta-regression analysis was conducted using Comprehensive Meta-analysis Software. Additional sensitivity analyses were undertaken to evaluate the robustness of the overall results. Twenty-eight clinical studies with 1218 patients reported from year 2001 to 2018 were included. The mean IVIG dose used ranges from 387 to 560mg/kg every 3 to 4 weekly, and mean IgG trough obtained ranges from 660 to 1280mg/dL. Random-effects meta-regression slope shows that IgG trough level increases significantly by 73mg/dL with every increase of 100mg/kg dose of IVIG (p < 0.05). Overall infection rates reduced significantly by 13% with every increment of 100mg/dL of IgG trough up to 960mg/dL (p < 0.05). This meta-analysis concludes that titrating the IgG trough levels up to 960mg/dL progressively reduces the rate of infections, and there is less additional benefit beyond that. Further studies to validate this result are required before it can be used in clinical practice.