Background:
With the growing number of biologics for severe asthma, it is important to endotype patients, in order to select the correct biologic. In most clinical settings easily available biomarkers such as blood eosinophils and FeNO are used for endotyping. However, there may be a mismatch between these biomarkers and airway inflammation. Therefore, examining airway inflammation by bronchoscopy or evaluation of induced sputum can identify airway inflammation more correctly. As bronchoscopy is an invasive procedure, induced sputum can be obtained with low risk in a nurse performed procedure. We present real-life data on the percentage of successful induced sputum procedures performed in a clinical setting.

Methods:

A retrospective study including all patients undergoing an induced sputum investigation from 2017-2022 in the severe asthma outpatient clinic at the Department for Respiratory Medicine and Allergy at Aarhus University Hospital was performed. We report the percentage of induced sputum procedures leading to representative samples at the first test and the number of successful procedures after the first test failed.

Results:

Between January 2017 and December 2022, 310 patients underwent an induced sputum procedure. Of these 310 patients, 49 (15,8%) had performed more than one test. The rate of success of the first examination was 59%. Median age was 55 years (17-86 years) and lung function (FEV1) was 2,31 l (0,68-4,66 l). There was no difference in sex (male 45%, female 55%).

Conclusion:

Examining inflammatory cells in induced sputum has a high diagnostic yield and is a safe and easily performed procedure in patients suffering from severe asthma.