Serum IgG Concentrations in Adult Patients Experiencing Virus-Induced Severe Asthma Exacerbations.

Background: Patients experiencing severe asthma exacerbations have a poorer quality of life and an increase in morbidity and mortality. Viruses are frequently involved in asthma exacerbations.

Objective: To determine the value of measuring serum IgG concentrations in asthma exacerbations and assess their link with viral infections in patients hospitalized for asthma.

Methods: Patients hospitalized for asthma exacerbation were included in an observational study from January 1, 2015, to December 31, 2015. Serum IgG concentrations on admission were compared between patients with a positive upper airway viral sample and those with a negative viral sample.

Results: Among the 82 patients included, those with positive viral nasopharyngeal samples (n = 40) presented with lower serum IgG concentrations during exacerbation than those with a negative viral sample (n = 42) (10.1 ± 2.3 g/L vs 11.5 ± 3.6 g/L; P < .05). The median concentration of serum IgG was lower in patients hospitalized for more than 3 days compared with those hospitalized for less than 3 days (10.0 g/L [8.2-12.4] vs 11.4 g/L [10.1-12.8]; P < .05) and in patients who received oral corticosteroid therapy for more than 5 days compared with those treated with oral steroids for less than 5 days (10.1 g/L [8.3-12.2] vs 11.6 g/L [10.0-13.8]; P < .05).

Conclusions: Serum IgG level was significantly lower when asthma exacerbations were associated with positive viral samples. The patients with lower serum IgG concentrations required longer hospitalizations and longer courses of steroids.