Total number of exacerbations per year in each class of exacerbation the year before and the year after Ig treatment.

<p>Black bars represent numbers of exacerbations before Ig treatment. White bars represent numbers of exacerbations after Ig treatment. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142205#sec006" target="_blank">Methods</a> section for definition of each class of COPD exacerbation. The overall decrease in number of exacerbations ignoring the clustering of events among patients was an 84.9% reduction in moderate AECOPD events, 91.7% in severe AECOPD events and 86.2% in moderate or severe AECOPD.