Materials and methods
This was an exploratory retrospective analysis of data pooled from three pivotal trials of the IVIG products Gammaplex 5% and Gammaplex 10%, (immune globulin intravenous [human], Bio Products Laboratory, Elstree, UK) for the treatment of PI. Characteristics of the pooled trials (This retrospective pooled analysis did not directly engage any patients. All trials included in the analysis were approved by an institutional review board/ethics committee at each study center and obtained written informed consent from each participant (or their parent/guardian, if applicable) to participate in the study. Participants from the included studies agreed to have their results published.