Abstract
Background: Surfactant protein D (SP-D) is a lung-specific protein proposed to predict clinical outcomes in patients with chronic obstructive pulmonary disease (COPD). However, the changes in serum SP-D during acute exacerbation (AECOPD) episodes and the relationship of serum SP-D with the overall severity of the disease in stable COPD (SCOPD) remain unclear.Methods: Serum SP-D levels were analyzed in three groups, including AECOPD (n=40), SCOPD (n=71), and controls (n=60). In AECOPD group, serum SP-D levels were determined at 1, 5, 14, and 30 days post-exacerbation. In SCOPD group, BODE (body mass index, airflow obstruction, dyspnea, exercise capacity) index was evaluated for severity assessment.Results: Serum SP-D levels were sequentially elevated from the controls to the SCOPD, and then to the AECOPD (p< 0.001). During an AECOPD episode, the raised serum SP-D levels subsided at day 5 (p> 0.05), fell markedly at day 14 (p< 0.001), and continued to decline at day 30 (p< 0.001). Among patients with SCOPD, serum SP-D levels correlated positively with the BODE index (p< 0.01).Conclusions: The longitudinal changes in serum SP-D levels during an AECOPD episode suggest that SP-D may be a potential systemic biomarker for COPD exacerbation. The correlation of serum SP-D levels with the BODE index suggests that circulating SP-Ds can reflect the overall severity of SCOPD.
Highlights
Chronic obstructive pulmonary disease (COPD) is a major medical problem, as well as a leading cause of morbidity and mortality among adults
Two cases in the acute exacerbation of COPD (AECOPD) group were excluded from the final analysis because the patients had persistent symptoms that did not improve after treatment until the 30th day of the exacerbation
Multiple regression analysis revealed that the serum Surfactant protein D (SP-D) levels were significantly correlated inversely with forced expiratory volume in the 1st second (FEV1)%pred [beta coefficient = −0.563, and 95% confidence interval (CI) = −2.324 to −1.113], and positively with BODE index
Summary
Chronic obstructive pulmonary disease (COPD) is a major medical problem, as well as a leading cause of morbidity and mortality among adults. The current definition recognizes COPD as a multicomponent disease associated with systemic inflammation [1], which contributes to some of the extra-pulmonary consequences of COPD [2,3,4]. Both pulmonary and systemic inflammation flare up during episodes of acute exacerbation of COPD (AECOPD) that occur as natural events in patients [5]. Ing AECOPD is associated positively with systemic inflammation, with a variety of systemic markers elevated in the circulation [6,7] Most of these circulating biomarkers, such as C reactive protein (CRP) and tumor necrosis alpha, are not lung-specific. The relationship of the serum SP-D levels to the BODE index in SCOPD is ascertained
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