Surfactant Protein a (SP-A) Is a Prognostic Molecular Biomarker in Acute Respiratory Distress Syndrome
The problem of predicting the development and outcomes of acute respiratory distress syndrome (ARDS) remains to be solved. Objective: to estimate the informative value of the plasma levels of surfactant protein A (SP-A) as a prognostic biomarker for the development and outcome of ARDS in patients with severe pyoseptic complications in critical conditions. Subjects and methods. This investigation was conducted at the Research Institute of General Reanimatology (RIGR), Russian Academy of Medical Sciences, in 2010—2012. It enrolled 80 patients (including 25 analyzed ones) in accordance with the inclusion and exclusion criteria, as well as 30 apparently healthy donors. ARDS and its stages were diagnosed using the RIGR criteria. Plasma SP-A levels were determined by enzyme immunoassay using a Human Surfactant Protein A ELISA, RD191139200R kit (BioVendor, USA). The findings were statistically analyzed using a Statistica 7.0 package.Sensitivity and specificity of SP-A testing were determined by ROC analysis. The difference between groups at p<0.05 was considered significant. Results. In patients with ARDS plasma SP-A level was higher than in those without ARDS within the whole study independing on a day of testing. There were no significant differences between plasma SP-A levels in the patients with Stages 1 and 2 ARDS. On day 1, the plasma SP-A content of ≥24.5 ng/ml had a sensitivity of 60.0% and a specificity of 85.7% in predicting the development of ARDS on days 4—5 of intensive care unit admission (the area under the curve 0.74; 95% confidence interval, 0.527—0.872; p=0.0031). On study day 1, the SP-A level of ≥38.8 ng/ml had a sensitivity of 65.0% and a specificity of 80.0% in predicting a fatal outcome in patients with ARDS (the area under curve 0.74; 95% confidence interval, 0.577—0.866; p=0.0026). Conclusion. On a day when a severe pyoseptic complication was diagnosed, the SP-A level of ≥24.5 ng/ml served as a sensitive and specific prognostic biomarker for the development of ARDS on days 4—5 of an intensive care unit stay. Within the first 24 hours (on the day when ARDS was diagnosed), the plasma SP-A content of ≥38.8 ng/ml was a sensitive and specific prognostic biomarker for death prediction in ARDS.