Is undifferentiated spondyloarthritis a discrete entity? A debate

The concept of undifferentiated spondyloarthritis has been introduced recently to describe a clinical setting where the classical features of spondyloarthritis (SpA) are not fully present. Whether this is a discrete entity was the basis of a debate during the 4th International Congress on Controversies in Rheumatology & Autoimmunity held in Bologna, Italy 9-11 March 2017. The pro and con aspects of the debate are presented. The implications of the debate are important ranging from diagnostic aspects to consequences for the society and the payers.