Do we need new trial designs in spondyloarthritis?

In the last two decades drug trials in ankylosing spondylitis (AS) have been extremely successful and many effective new drugs have been approved for the treatment of patients with AS. In 2009, new classification criteria for axial spondyloarthritis (axSpA) have been released that capture not only AS, but also patients with presumably earlier non-radiographic axSpA. These criteria have served as inclusion criteria for patients to be enrolled in drug trials for the indication of nr-axSpA. The theme to be discussed in this article pertains to changes in the design of clinical trials required to optimize the process of drug-testing and -approval in a changed environment. Additional treatment criteria (MRI-and CRP-positivity), better response measurement (ASDAS) and trial homogeneity will be addressed against the background of the expansion of the disease spectrum of axSpA which has been the consequence of the new classification criteria for axSpA.