A compound attribute that is the ratio of amount of epithelial discoidin domain-containing receptor 1 (human) in blood to amount of pulmonary surfactant-associated protein D (human) in blood. The trait is DDR1/SFTPD protein level ratio in blood (Ontology of Biological Attributes id OBA_2054073). Also known as: the ratio of amount of epithelial discoidin domain-containing receptor 1 (human) in blood to amount of pulmonary surfactant-associated protein D (human) in blood.