Background: A number of studies have been conducted to investigate the association between serum surfactant protein D (SP-D) concentration and chronic obstructive pulmonary disease (COPD) risk. However, the results are inconsistent. This systematic review and meta-analysis aim to investigate whether serum SP-D concentration is a potential biomarker for COPD diagnosis.
Methods: We searched Web of Science, PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang Database from inception through July 18, 2018. The standardized mean difference (SMD) with 95% confidence interval (CI) was used to investigate the effect sizes.
Results: Seventeen eligible studies from a total of 4,639 subjects were finally included in this systematic review and meta-analysis. The results indicated that serum SP-D levels in COPD patients were significantly higher than those in controls (SMD = 1.01, 95% CI = 0.62 - 1.41, p < 0.001). We also found that serum SP-D concentration in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients was significantly higher than that in stable COPD patients (SMD = 1.50, 95% CI = 0.92 - 2.08, p < 0.001), and serum SP-D concentration was higher in smokers than in nonsmokers in healthy population (SMD = 1.50, 95% CI = 0.35 - 2.64, p = 0.025).
Conclusions: The current systematic review and meta-analysis indicates that serum SP-D levels may be a promising biomarker for COPD. In particular, increased serum SP-D levels appear to be associated with acute exacerbation of COPD and smoking in healthy population.