Surfactant proteins (SPs) have been studied in COPD patients as biomarkers of disease severity and as predictive factors of unfavorable outcomes. The aim of this exploratory study was to evaluate serum levels of SP-A, SP-B, SP-C, and SP-D in patients with COPD both during AECOPD and in stability and to test their possible associations with disease severity and with the development of new exacerbation events. 20 consecutive COPD patients hospitalized for AECOPD were included. Serum SP levels were measured on admission, at discharge, and on stability. SP-A levels were significantly lower both on admission and at discharge in patients with early relapse compared to those with late or no relapse (29.2 ± 9.1 vs. 43.9 ± 16.9 ng/ml, p = 0.037, and 24.3 ± 2.8 vs. 39.3 ± 14.2 ng/ml, p = 0.011, respectively). SP-B levels were found to have a trend to be higher at discharge and significantly higher on stability in patients experiencing an early relapse compared to those with late or no relapse (52.5 ± 31.6 vs. 31.4 ± 32.3 ng/ml, p = 0.052 and 64.8 ± 32.6 vs. 32.8 ± 25.6 ng/ml, p = 0.024, respectively). Finally, the ROC analysis showed that serum SP-A, SP-B, and SP-C levels at discharge, seemed to be significant predictors of early relapse. Our conclusion is that serum levels of SPs might be related to disease outcomes in COPD patients.
Keywords: Biomarkers; COPD exacerbations; Lung function; Surfactant proteins.