Variability of total serum IgE in moderate-to-severe asthmatic patients

Long-term variability of serum total IgE (sIgE tot ) has been reported in asthmatics. This study evaluates the dynamics and the factors predictive of this variability. sIgE tot levels were prospectively measured over 1 year in 41 moderate-to-severe asthmatics treated with high-dose of inhaled corticosteroids and long-acting β 2 agonists (and untreated with omalizumab). Patients were divided into 3 groups according to their baseline sIgE tot level: low (≤75 IU/mL; n=10), intermediate (76-700 IU/mL; n=20) or high (>700 IU/mL; n=11). The sIgE tot variability and factors predictive of IgE tot variability were studied. The mean sIgE tot (whole group) fluctuated over 1 year and showed an overall non-significant decrease from baseline ( p =0.21). Four to 29% of the sIgE tot variability depended on within-patient variability. No factor predictive of the within-patient variability was identified in the intermediate sIgE tot group. In the low sIgE tot group, however, the level of sIgE tot increased over 1 year in patients exposed to allergens ( p p =0.011), and the odds of having an exacerbation since the previous visit increased by 30% if sIgE tot increased by 100 IU/mL ( p tot group, the odds of having an exacerbation since the previous visit decreased by 5% if sIgE tot increased by 100 IU/mL ( p =0.005). These trends should be confirmed in a bigger cohort. In this small cohort of moderate-to-severe asthmatics, a limited within-patient variability of sIgE tot levels was observed over 1 year. This variability depended on allergen exposure, OCS use (probably related to exacerbation management) and exacerbations in patients with low and high baseline sIgE tot .