Relationship between airway neutrophilia and ageing in asthmatics and non‐asthmatics. Issue 5 (21st June 2013)

• Record Type: Journal Article
• Authors: Brooks, Collin R.; Gibson, Peter G.; Douwes, Jeroen; Dalen, Christine J. Van; Simpson, Jodie L.
• Is Part Of: Respirology. Volume 18:Issue 5(2013)
• Page Start: 857
• Page End: 865
• Publication Date: 2013-06-21
• Subjects: Respiratory organs -- Diseases -- Periodicals; Respiratory organs -- Periodicals; 612.2
• DOI: 10.1111/resp.12079
• Languages: English
• ISSNs: 1323-7799

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <sec id="resp12079-sec-0001" sec-type="section"> <title>Background and objective</title> <p>Increased sputum neutrophilia has been observed in asthma, but also during normal ageing in asthmatics and non‐asthmatics. It remains unclear what constitutes 'normal' neutrophil levels in different age groups.</p> </sec> <sec id="resp12079-sec-0002" sec-type="section"> <title>Methods</title> <p>We assessed the relationship between age and airway neutrophils of 194 asthmatics and 243 non‐asthmatics (age range: 6–80 years). Regression analyses were used to assess this relationship adjusted for confounders including asthma status, atopy, gender, smoking and current use of inhaled corticosteroids (ICS). Age‐corrected reference values for different age groups were determined using the 95th percentile of non‐asthmatic participants.</p> </sec> <sec id="resp12079-sec-0003" sec-type="section"> <title>Results</title> <p>Age was positively associated with sputum neutrophils in both asthmatic and non‐asthmatic adults (0.46% neutrophil increase/year (95% confidence interval (CI) 0.18, 0.73) and 0.44%/year (0.25, 0.64, respectively), but no association was found in the <20‐year age category. Individuals with high sputum neutrophil counts (>95th percentile of non‐asthmatic counts for any given age group) were significantly more likely to be asthmatic (odds ratio = 2.5; 95% CI: 1.3, 5.0), with the greatest effect observed in the older age group. Other factors that independently associated with increased sputum neutrophil levels included atopy in non‐asthmatic adults, male gender and current use of ICS in asthmatic adults. Age‐specific reference values for neutrophil percentage were under 20 years‐76%, 20–40 years‐62%, 40–60 years‐63% and over 60 years‐67%.</p> </sec> <sec id="resp12079-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Airway neutrophilia is related to age in adults, with a neutrophilic asthma phenotype present in older adults. The use of appropriate age‐specific reference values is recommended for future studies aimed at elucidating the role of neutrophils in asthma.</p> </sec> </abstract>