The value of surfactant protein a in evaluating the severity and prognosis in community-acquired pneumonia patients.

Background: Previous research has discovered that surfactant protein A (SP-A) is involved in the pathophysiology processes of certain lung illnesses. However, no definitive clinical studies have delved into the function of SP-A in individuals afflicted with community-acquired pneumonia (CAP). A prospective cohort study was used to investigate the relationships between blood SP-A levels and the severity and prognosis among CAP patients.

Materials and methods: This study included 260 patients with CAP. Clinical traits and demographic data were examined during hospitalization. The concentrations of serum SP-A and serum interleukin-6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA). In addition, to evaluate the severity of CAP, a variety of scores, including the CURB-65, PSI, SMART-COP, and APACHE II, were employed.

Results: The serum levels of SP-A at admission exhibited a gradual decline as the severity scores of CAP increased. Through Spearman correlation analysis, we observed an association between serum SP-A and some clinical indicators among CAP patients. Furthermore, results from a multiple linear regression model suggested changes in PSI scores (-17.868 scores, 95% CI: -32.743, -2.993) affect serum SP-A more than CURB-65 (-0.547 scores, 95% CI: -0.964, -0.131), SMART-COP (-1.097 scores, 95% CI: -1.889, -0.304) and APACHE II (-3.475 scores, 95% CI: -5.874, -1.075) with age, hypertension, diabetes mellitus, cerebral infarction, coronary heart disease, and bronchitis adjusted. In addition, the prognosis in CAP patients was monitored. Throughout their hospital stay, higher serum levels of SP-A decreased the risks of mechanical ventilation (RR: 0.315; 95% CI: 0.106, 0.937), vasoactive agents (RR: 0.165; 95% CI: 0.034, 0.790), intensive care unit (ICU) admissions (RR: 0.218; 95% CI: 0.066, 0.717) and longer hospital stays (RR: 0.397; 95% CI: 0.167, 0.945).

Conclusion: In CAP patients, inverse dose-response correlations exist between serum SP-A levels with severity scores as well as prognosis at admission, suggesting that SP-A may take part in the CAP pathophysiological processes. Moreover, lower serum SP-A on admission is associated with an elevated prognostic risk of mechanical ventilation, the use of vasoactive agents, longer hospital stays, ICU admission, and mortality. Therefore, as a biomarker, SP-A may have the potential to predict the severity and poor prognosis of CAP patients.