Abstract:

Purpose: Serum surfactant protein D (SP-D) plays roles in the body such as protection against viral infection, bacterial and fungal clearance, clearance of apoptotic cells and suppression of inflammation. This study aims to examine the relationship between SP-D level and coronavirus disease (COVID-19) severity. Methods: 80 patients (30 with mild disease and 50 with severe/critical COVID-19), and 50 healthy volunteers were enrolled in the study. SP-D levels were analyzed by ELISA in serum samples. Results: The median of SP-D was found to be 2.47 (1.67-7.79) ng/ml in mild disease and 5.65 (3.09-16.55) ng/ ml in severe/critical disease groups, while 2.89 (10.8-6.24) ng/ml in the healthy controls. The differences in SP-D levels between the severe/critical disease group compared to both mild disease and control groups were found statistically significant (p=0.007 and 0.001, respectively). ROC analysis showed greater AUC for the serum SP-D levels of the severe/critical COVID-19 patients compared to mild COVID-19 disease patients (AUC=0,691, 95% CI=0.56-0,822; p=0.004). Furthermore, SP-D levels were 86% sensitive and 51.6% specific at 2.44 ng/ml level (p=0.004) to detect severe/critical patients. Conclusion: SP-D levels is useful for COVID-19 patients in the prediction of clinical severity and prognosis. SP-D is a valuable biomarker for predicting the clinical severity and prognosis.

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