Abstract
BACKGROUND: Interstitial lung disease (ILD) is a large group of heterogeneous pulmonary disorders with complex etiologies. Noninvasive biomarkers serve as important tools for diagnosis and predicting prognosis of ILD. There is no comprehensive evidence for the clinical value of serum surfactant protein A (SP-A) in ILD population. METHODS: A systematical search was performed in PubMed, Web of Science, Cochrane Library, Embase and Scopus for English literatures published before May 1, 2024. The Newcastle-Ottawa scale was use for quality assessment of literatures. The weighted mean difference of serum SP-A in ILD with different disease states was summarized and analyzed. Sensitivity analysis was proceeded by sequentially excluding 1 study at a time and merging the remaining studies. Publication bias was judged by funnel plots, Egger's test and trim-and-fill method. RESULTS: A total of 22 studies comprising 2573 ILD patients were included in this meta-analysis. The results revealed that serum SP-A levels were significantly higher in ILD group compared to control group (weighted mean difference [WMD] = 29.82 ng/mL, 95% confidence interval [CI]: 17.15-42.59), serum SP-A levels of ILD patients in progression group were statistically higher than stable group (WMD = 18.36 ng/mL, 95% CI: 6.13-30.59), acute exacerbation group were significantly higher than non-acute exacerbation group (WMD = 16.47 ng/mL, 95% CI: 6.68-26.26), death group were distinctly higher than survival group (WMD = 23.63 ng/mL, 95% CI: 18.73-28.53) respectively. CONCLUSION: Elevated serum SP-A emerges as a pivotal noninvasive biomarker for assessing disease states and prognosis in ILD patients.