Military biobank of serial serum samples was used to identify biomarkers of imminent RA (vs reactive arthritis or healthy controls). Soluble programmed cell death receptor-1 (sPD-1) best predicted seropos. RA w/in 6mos of Dx. Specif >89%; sensitivity 48% https://t.co/djOGhLeCIi https://t.co/DzKqwteQku