COMP/DPP4 protein level ratio in blood (Ontology of Biological Attributes id OBA_2053840) can be described as follows. A compound attribute that is the ratio of amount of cartilage oligomeric matrix protein (human) in blood to amount of dipeptidyl peptidase 4 (human) in blood. Also known as: the ratio of amount of cartilage oligomeric matrix protein (human) in blood to amount of dipeptidyl peptidase 4 (human) in blood.