Abstract
We have recently reported that exhaled nitric oxide (FeNO), a measure of Th2-driven airway inflammation, and blood eosinophil count, a marker of systemic eosinophil inflammation, had an additive value with regard to asthma attacks in a population-based study. However, this has not yet been addressed in an asthma population.Measurements of FeNO (normal <25 ppb, elevated >=25 ppb) and serum eosinophil cationic protein (S-ECP) (normal <20 ng/mL, elevated >=20 ng/mL) were done in 375 adults with asthma (59.2% women, aged 41.4 +/- 13.9 years) within the Swedish GA2LEN study. Asthma attacks the last three months were self-reported.Normal FeNO and S-ECP were found in 49.3% of the patients. Both elevated FeNO and S-ECP were found in 12.8% of the population, and these subjects had a higher prevalence of asthma attacks than subjects with both normal FeNO and S-ECP (47.9% vs 22.1%, p=0.001). Subjects with singly elevated FeNO or S-ECP each represented 18.9% of the population and had a prevalence of asthma attacks of 28.2% and 31.0%, respectively. Having both elevated FeNO and S-ECP, compared to both normal FeNO and S-ECP, related to an odds ratio of 3.4 (1.6, 6.9) for asthma attacks last 3 months after adjusting for gender, age, study center, atopy, smoking history, chronic rhinosinusitis, and BMI.In conclusion, the simultaneous presence of local airway inflammation and systemic eosinophilic inflammation related to presence of asthma attacks the last three months. This reinforces the need to map both local and systemic inflammation in patients with asthma in order to identify individuals at high risk of exacerbations and to treat them accordingly.