Inflammatory subtypes in asthma: Assessment and identification using induced sputum

The authors sought to investigate the detection of non-eosinophilic asthma using induced sputum. Although this is an important subtype of clinical asthma, its recognition is not standardized.

Adult non-smokers with asthma and healthy controls underwent sputum induction and hypertonic saline challenge. Non-eosinophilic asthma was defined as symptomatic asthma with normal sputum eosinophil counts. The normal range for sputum eosinophil count was determined using the 95th percentile from the healthy control group as a cut-off point.