IFNA1 and neutropenia: Our aggregation of the data for a safety profile of PEG-IFN-α2a and 2b showed that discrepancies in dose modification and treatment withdrawal in both types of PEG-IFN were not significant in total, but neutropenia < 750 c/mm3 was 1.5 times higher in PEG-IFN-α2a, with no observed heterogeneity among studies.