Chest
Volume 132, Issue 6, December 2007, Pages 1871-1875
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Original Research
Asthma
Association Between Neutrophilic Airway Inflammation and Airflow Limitation in Adults With Asthma

https://doi.org/10.1378/chest.07-1047Get rights and content

Background

There is debate about the mechanisms of persistent airflow limitation in patients with asthma. Chronic inflammation is assumed to be important, although there is limited and contradictory information about the relationship between airway inflammation and postbronchodilator FEV1.

Methods

We have assessed the cross-sectional relationship between prebronchodilator and postbronchodilator FEV1 and measures of airway inflammation after allowing for the effects of potential confounding factors. Multivariate analysis was performed on data collected from 1,197 consecutive patients with asthma seen at the respiratory outpatient clinic at Glenfield Hospital between 1997 and 2004. Relationships between induced sputum total neutrophil and differential eosinophil cell counts, and prebronchodilator and postbronchodilator lung function were examined.

Results

Sputum total neutrophil but not differential eosinophil count was associated with lower postbronchodilator FEV1. Both differential eosinophil and total neutrophil count were associated with lower prebronchodilator FEV1. These effects were independent after adjustment for age, smoking, ethnicity, asthma duration, and inhaled corticosteroid use. A 10-fold increase in neutrophil count was associated with a 92 mL reduction (95% confidence interval, 29 to 158; p = 0.007) in postbronchodilator FEV1.

Conclusions

In this large heterogeneous population of adults with asthma, we have shown that prebronchodilator FEV1 is associated with neutrophilic and eosinophilic airway inflammation, whereas sputum total neutrophil counts alone are associated with postbronchodilator FEV1. This supports the hypothesis that neutrophilic airway inflammation has a role in the progression of persistent airflow limitation in asthma and raises the possibility that this progression and the development of COPD share a common mechanism.

Section snippets

Subjects

A total of 1,197 consecutive patients seen in the respiratory outpatient clinic at Glenfield Hospital between November 1997 and March 2004 were included in the study. Glenfield Hospital is a secondary care facility covering a population of 1 million people of mixed ethnicity and social class. The main indications for referral for assessment of airway disease were diagnostic uncertainty and poor symptom control. Informed consent for the assessment of airway inflammation was obtained for all

Results

Patient demographics are given in Table 1.

Discussion

We have shown a weak relationship between prebronchodilator and postbronchodilator FEV1 and sputum measures of airway inflammation in a large heterogeneous population of adults with asthma. Postbronchodilator FEV1 was associated with sputum total neutrophil count. Smoking, ICS use, and asthma duration were also associated with a lower postbronchodilator FEV1. A raised sputum neutrophil count was associated with a lower prebronchodilator FEV1 but to a lesser extent than the differential sputum

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  • Cited by (0)

    The authors have no conflicts of interest to disclose.

    Dr. Shaw has received a travel grant from GlaxoSmithKline and lecture fees from Astra-Zeneca. Dr. Berry has received a travel grant from GlaxoSmithKline. Dr. Brightling has received lecture fees from Astra-Zeneca and GlaxoSmithKline and a research grant from Cambridge antibody technology. Dr. Wardlaw has received lecture fees from Altana pharmaceuticals and MSD and research grants from Wyeth, Astra-Zeneca, and GlaxoSmithKline. Dr. Pavord has received lecture fees and research grants from Astra-Zeneca and GSK.

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