Effectiveness of a panel of sputum markers in smokers with and without COPD to detect pulmonary progression towards functional impairment

<b>Background:</b> COPD is a complex disorder which tend to be underrated. Since spirometry is the only method to evaluate it, many patients remain undiagnosed until the more advanced stages. Surrogate measures may be needed to achieve a more complete assessment. Currently monitoring functional changes remains the best approach to trace disease progression and outcome. In this context it may be possible that greater specificity and sensitivity may be reached by screening biomarker panels. <b>Objectives:</b> To test the effectiveness of a combination of biomarkers measured in sputum from symptomatic smokers with and without COPD, as tracers of pulmonary inflammation and progression towards functional impairment. <b>Methods:</b> We analyzed Human Neutrophil Peptides (HNP), Interleukin-8 (IL-8), Neutrophil Elastase (NE) and Matrix Metalloproteinase-9 (MMP-9) sputum levels in 184 patients with smoking history affected (n=119) or not (n=65) by COPD, following GOLD guidelines to assess severity. Canonical variables, using discriminant function analysis, were generated to optimize the accuracy of selected variables in predicting obstructive impairment and exacerbations frequency. <b>Results:</b> The combination of the 4 biomarkers was able to correctly allocate 89.1% of smokers without COPD (95% CI 84.6-93.6), 73.5% (95% CI 61.1-85.8) of COPD individuals with less than 2 exacerbations/yr and 80.0% (95% CI 70.6-89.4) of COPD subjects with 2 or more exacerbation/yr. <b>Conclusions:</b> Our results showed that a combinational approach could significantly contribute to predict exacerbations frequency and functional impairment and may be a support in optimizing therapeutic strategies.