The 2010 Tree Algorithm for classifying definite RA (green circles) or for excluding its presence (red circles) among those who are eligible to be assessed by the 2010 ACR-EULAR RA Classification Criteria

APR = acute-phase response. Serology: + = low-positive for rheumatoid factor (RF) or anti - citrullinated protein antibody (ACPA); serology: ++ = high-positive for RF or ACPA; serology: +/++ = serology either + or ++.

Aletaha D, Neogi T, Silman A, Funovits J, Felson D, et al. 2010 Rheumatoid Arthritis Classification Criteria: An American College of Rheumatology / European League Against Rheumatism Collaborative Initiative. Arthritis Rheum 2010;62:2569-81.