Research

Inflammation in sputum relates to progression of disease in subjects with COPD: a prospective descriptive study

David G Parr¹ , Andrew J White² , Darren L Bayley³ , Peter J Guest⁴ and Robert A Stockley³

¹  Department of Respiratory Medicine, University Hospitals of Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK

²  Department of Respiratory Medicine, Gloucester Royal Infirmary, Gloucester, UK

³  Lung Investigation Unit, University Hospital of Birmingham, Edgebaston, Birmingham, B15 2TH, UK

⁴  Department of Radiology, Queen Elizabeth Hospital, Edgebaston, Birmingham, B15 2TH, UK

author email corresponding author email

Respiratory Research 2006, 7:136doi:10.1186/1465-9921-7-136

Published:	18 November 2006

Abstract

Background

Inflammation is considered to be of primary pathogenic importance in COPD but the evidence on which current understanding is based does not distinguish between cause and effect, and no single mechanism can account for the complex pathology. We performed a prospective longitudinal study of subjects with COPD that related markers of sputum inflammation at baseline to subsequent disease progression.

Methods

A cohort of 56 patients with chronic bronchitis was characterized in the stable state at baseline and after an interval of four years, using physiological measures and CT densitometry. Sputum markers of airway inflammation were quantified at baseline from spontaneously produced sputum in a sub-group (n = 38), and inflammation severity was related to subsequent disease progression.

Results

Physiological and CT measures indicated disease progression in the whole group. In the sub-group, sputum myeloperoxidase correlated with decline in FEV₁ (rs = -0.344, p = 0.019, n = 37). LTB4 and albumin leakage correlated with TLCO decline (rs = -0.310, p = 0.033, rs = -0.401, p = 0.008, respectively, n = 35) and IL-8 correlated with progression of lung densitometric indices (rs = -0.464, p = 0.005, n = 38).

Conclusion

The data support a principal causative role for neutrophilic inflammation in the pathogenesis of COPD and suggest that the measurement of sputum inflammatory markers may have a predictive role in clinical practice.