Total IgE variability is associated with future asthma exacerbations: a one-year prospective cohort study.

BACKGROUND: Few prospective studies have investigated the relationship between IgE variability and risk of asthma exacerbations (AEs).

OBJECTIVE: To explore the relationship between IgE variability and AEs.

METHODS: Recruited patients with stable asthma underwent two serum total IgE tests within a month (at screening [baseline IgE] and one-month) to obtain coefficient of variation (CV) of base-10 log-transformed IgE. Patients with IgE CV were divided into IgE CV-high and IgE CV-low cohorts based on the CV's median and followed up within a 12-month period during which, the association between IgE variability and AEs was explored using a negative binomial regression model.

RESULTS: IgE CV levels obtained from 340 patients classified the patients into two groups (n=170 for the IgE CV-high and IgE CV-low groups, respectively) based on the serum total IgE CV median of 2.12% (Q1, Q3: 0.98%, 3.91%). IgE CV-high patients exhibited worse asthma control and lung function, more marked airway inflammation, and received more intensive medication use compared to IgE CV-low patients. IgE CV-high patients exhibited increased rates of moderate-to-severe (adjusted rate ratio [RRadj ]=2.88, 95% CI=[1.65, 5.03], P<0.001) and severe (RRadj =2.16, 95% CI=[1.08, 4.32], P=0.029) AEs during the follow-up year compared to IgE CV-low patients. Furthermore, sputum IL-6 partially mediated the associations between IgE CV with moderate-to-severe and severe AEs.

CONCLUSIONS: Variability in total serum IgE levels is an easily obtained and practical measure for predicting AEs. Future studies are needed to investigate whether IgE variability can be used to guide precision medicine in asthma.