Infection Rates in PI Patients Decline with Increasing IVIG Dosages and IgG Trough Level

A systematic review and meta-regression analysis of published clinical studies was conducted to evaluate the impact of increasing immunoglobulin G (IgG) trough levels on infection rates in patients with primary immunodeficiency disorders (PI) receiving intravenous immune globulin (IVIG) treatment.

From a search of all relevant articles published between 2001 and 2018, 28 clinical studies reporting on 1,218 patients were included. Across all studies, the mean IVIG dose ranged from 387 mg/kg to 560 mg/kg every three to four weeks, and mean IgG trough level ranged from 660 mg/dL to 1,280 mg/dL. A random- effect meta-regression slope analysis found the IgG trough level increases significantly by 73 mg/dL with every increase of 100 mg/kg in the dose of IVIG. Overall infection rates declined significantly by 13 percent with each increment of 100 mg/dL in the IgG trough level, up to 960 mg/dL (p < 0.05).

The study authors concluded that titrating the IgG trough level up to 960 mg/dL progressively reduces the infection rate in PI patients, but there is less incremental benefit above this trough level. “Further studies to validate this result are required before it can be used in clinical practice,” they added.