Intrasubject Variability in Total IgE Levels in Patients with Moderate to Severe Persistent Allergic Asthma Over 1 Year.

Background: Longitudinal variability in serum IgE levels has not been prospectively studied in people with moderate to severe allergic asthma.

Objective: We investigated change in serum IgE concentrations over 1 year, and its relationship with lung function, asthma control, asthma pharmacotherapy, allergy season, asthma exacerbations, body mass index, and demographic factors.

Methods: Seventeen patients with moderate to severe persistent allergic asthma were followed for 1 year. Variability in serum IgE level was explored using a linear mixed regression model treating a change of 10% or more in IgE concentration and combined change of 10% or more and an absolute change of 50 IU/mL as dichotomous variables.

Results: For consecutive visits every 2 months, the mean percent change in serum IgE level was 23 ± 3 (P < .001). Probability of having a greater than 10% change in serum IgE level in a subsequent visit was 69% (95% CI, 58%-78%; P < .001). Variability in IgE level could have affected clinical decisions for anti-IgE treatment (dosing and/or treatment candidacy) in 7 of 17 patients. There were no statistically significant associations of IgE level variability with demographic characteristics and lung function, exacerbations, allergy season, Asthma Control Test scores, peak flow rates, pharmacotherapy, or body mass index.

Conclusions: Serum IgE concentrations exhibit variability over time among individuals with moderate to severe persistent allergic asthma. The factors that contribute to IgE level variability and the impact of these findings on clinical outcomes deserve further study.