IGHE and asthma: To assess the interaction between total IgE levels and the intervention on asthma or recurrent wheeze, subgroups were stratified by the median total IgE level at 5 months because almost half were not detectable at age 5 months (range, <3 to 239 IU/mL) and by quartiles of the total IgE level at age 24 months, because levels ranged broadly from less than 3 to 1250 IU/mL (Figure 4).