Measuring Biomarkers for Rheumatoid Arthritis

De-identified serum specimens were tested in the Clinical Laboratory Improvement Amendment-certified clinical laboratory of Crescendo Bioscience (South San Francisco, CA, USA). A multiplexed, sandwich immunoassay (Mesoscale Discovery, Rockville, MD, USA) was used to measure concentrations of the 12 MBDA protein biomarkers: vascular cell adhesion molecule 1, epidermal growth factor, VEGF alpha, IL-6, TNF receptor-I, MMP-1, MMP-3, YKL-40, leptin, resistin, serum amyloid A and CRP. Concentration values were combined using a previously validated algorithm that generates an integer score on a scale of 1–100 [2 ]. Samples were tested from 2012 to 2017, using the same immunoassay instruments, reagents and algorithm as those used for the Vectra DA commercial test manufactured by Crescendo Bioscience.