RT Journal Article
SR Electronic
T1 Sputum neutrophil counts in healthy subjects: relationship with age
JF ERJ Open Research
JO erjor
FD European Respiratory Society
SP 00246-2022
DO 10.1183/23120541.00246-2022
VO 8
IS 4
A1 Beech, Augusta
A1 Singh, Dave
YR 2022
UL http://openres.ersjournals.com/content/8/4/00246-2022.abstract
AB A threshold of ∼60% has commonly been used in asthma and COPD studies to define the presence of neutrophilic airway inflammation. This threshold is based on relatively young healthy subject datasets. However, age-related increases in sputum neutrophils have been observed previously. We used a healthy cohort, with a comparatively wider age range, to re-evaluate the age-related increase in sputum neutrophils, analysing changes by decade. We also studied the long-term repeatability of sputum neutrophil counts.Differential sputum cell count data for healthy subjects (n=121) was retrospectively analysed. Subjects with a repeated count (mean interval 4.8 years) were included in longitudinal analysis.There was a significant positive association between age and sputum neutrophil % (rho=0.24, p<0.01), with 51.2% of subjects having a sputum neutrophil count >60%. Sputum neutrophil counts increased with each decade until ∼60 years where a plateau was observed. The baseline sputum neutrophil % increased significantly at repeated sampling (p=0.02), with excellent long-term repeatability (intraclass correlation coefficient=0.80).We confirm previous reports of an age-related increase in sputum neutrophil % in healthy individuals and identified a plateau which occurs at age ∼60 years. There was an increase in sputum neutrophil % during longitudinal follow-up, indicating that age-related neutrophilia is a progressive phenomenon. These findings question the use of an unadjusted threshold, in relation to age, to identify the presence of neutrophilic airway inflammation.There is an age-related increase in sputum neutrophil % in healthy individuals, with a plateau at age ∼60 years. Sputum neutrophil % increased during follow-up. Age-adjusted thresholds for sputum neutrophilia should be considered. https://bit.ly/3OcOrmO