- Title
- Relationship between airway neutrophilia and ageing in asthmatics and non-asthmatics
- Creator
- Brooks, Collin R.; Gibson, Peter G.; Douwes, Jeroen; Van Dalen, Christine J.; Simpson, Jodie L.
- Relation
- NHMRC
- Relation
- Respirology Vol. 18, Issue 5, p. 857-865
- Publisher Link
- http://dx.doi.org/10.1111/resp.12079
- Publisher
- Wiley-Blackwell Publishing Asia
- Resource Type
- journal article
- Date
- 2013
- Description
- Background and objective: 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. Methods: 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. Results: 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%. Conclusions: 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.
- Subject
- ageing; asthma; neutrophil; induced sputum
- Identifier
- http://hdl.handle.net/1959.13/1295304
- Identifier
- uon:18993
- Identifier
- ISSN:1323-7799
- Language
- eng
- Reviewed
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