Sensitization to Staphylococcus aureus enterotoxins (SEs) was linked to an increased subsequent risk for severe asthma and asthma exacerbations, according to the results of a nested case-control, longitudinal study from the 20-year Epidemiological Study of the Genetics and Environment of Asthma (EGEA) conducted in the European Union that were published in the European Respiratory Journal.
Investigators sought to evaluate the associations between SE-sensitization and the risk for asthma severity and exacerbations. The EGEA1 cohort, which was assessed between 1991 and 1995, was composed of 2047 individuals. This cohort study, EGEA2, was conducted between 2003 and 2007 included 225 adults, of whom 75 never had asthma or atopic dermatitis (controls), 76 had mild asthma, and 74 had moderate to severe asthma. Of these patients, 173 had SE-sensitization measured from samples that were collected 11 years earlier in EGEA1.
Cross-sectional associations were performed for both EGEA1 and EGEA2. The researchers used longitudinal analyses to assess the link between SE-sensitization in EGEA1 and the risk for severe asthma and exacerbations that were evaluated in the follow-up study. Adjustments were made according to age, gender, smoking status, presence of parental asthma/allergy, and skin prick test for house dust mites.
Results demonstrated that SE-sensitization varied between 39.1% in controls and 57.6% and 75.6% of patients with mild and severe asthma in EGEA, respectively. Longitudinal adjusted logistic regression analysis demonstrated an association between SE-sensitization and an increased risk for severe asthma, but not for mild asthma. In fact, SE-sensitization in EGEA1 was linked to severe asthma (adjusted odds ratio [aOR], 2.69; 95% CI, 1.18-6.15) and asthma exacerbations (aOR, 4.59; 95% CI, 1.40-15.07) that were evaluated 20 years later.
One study limitation was the sample size that led to wide CIs of the estimated ORs, which did not permit an evaluation of the role of SE-immunoglobulin E in asthma severity over time.
The investigators concluded that this is the first study to demonstrate that sensitization to SEs is associated with an increased risk of having asthma exacerbations years later. Study findings also showed that having a positive skin prick test to house dust mites was linked to a decreased risk for severe asthma.
Sintobin I, Siroux V, Holtappels G, et al. Sensitisation to staphylococcal enterotoxins and asthma severity: a longitudinal study in the EGEA cohort [published online July 8, 2019]. Eur Respir J. doi:10.1183/13993003.00198-2019