Background: The aim of this study was to test whether repeatable biomarkers collected from serum, bronchoalveolar lavage (BAL) and sputum of healthy smokers and smokers with COPD would have a prognostic value with respect to the decline in lung function over a 5 year period.
Methods: In 2006/2007 we had repeatedly collected serum, BAL and sputum of 23 healthy smokers and 24 smokers with COPD (GOLD II) and analysed a panel of more than 100 different parameters. In 2012 we reinvited these subjects to assess the change in lung function to enable the investigation of the potential prognostic value of the 2006/2007 markers and to determine the long-term repeatability of selected blood and serum markers. In this follow-up study we performed body-plethysmography, a blood gas analysis and collected blood and urine samples. The change in lung function was compared with 67 markers from BAL, sputum, serum and whole blood that were shown in the 2006/2007 assessment to be repeatable over a 6 week period.
Results: We were able to recruit 13 (54%) smokers with COPD and 11 (48%) former healthy smokers that participated in the 2006/2007 study. The decline in lung function was larger in COPD smokers; five of them changed to GOLD III, one to GOLD IV. Two healthy smokers changed to GOLD I. Blood cells, serum von Willebrand factor and alpha-1-antitrypsin showed a good repeatability over 5 years. In COPD smokers a weak correlation between 2006/2007 sputum markers of neutrophilic inflammation and the 5 year change in FEV1/FVC was found.
Conclusions: Our data suggests that inter-individual and group differences are maintained over a five year period. Despite the large panel of markers available for this analysis, a potential prognostic value appears to exist only for some sputum inflammatory markers. If these data can be confirmed in larger COPD cohorts, it would emphasize the value of sputum markers in clinical trials and support the assumption that an anti-inflammatory treatment can have long term benefits in COPD.