This study from The Netherlands included 176 patients with adult-onset severe refractory asthma (defined according to Global Initiative for Asthma criteria).
Patients with severe adult-onset asthma:
- were more often nonatopic (52% vs 34%)
- had more nasal symptoms and nasal polyposis (54% vs 27%)
- higher exhaled nitric oxide levels (38 vs 27 ppb)
- blood neutrophil counts (5.3 vs 4.0 x10(9)/L)
- sputum eosinophilia (11.8% vs 0.8%)
Eosinophil. Image source: Wikipedia.
Increased blood neutrophil (odds ratio, 10.9) and sputum eosinophil (odds ratio, 1.5) counts were independently associated with severe adult-onset disease.
The majority of patients with severe adult-onset asthma are nonatopic and have persistent eosinophilic airway inflammation. This suggests that severe adult-onset asthma has a distinct underlying mechanism compared with milder disease.
Severe adult-onset asthma: A distinct phenotype. Amelink M, de Groot JC, de Nijs SB, Lutter R, Zwinderman AH, Sterk PJ, Ten Brinke A, Bel EH. J Allergy Clin Immunol. 2013 Aug;132(2):336-41. doi: 10.1016/j.jaci.2013.04.052. Epub 2013 Jun 24.