The burden of disease in ankylosing spondylitis (AS) has been hard to grasp for doctors not directly involved in the care of these patients. With inflammation primarily affecting the axial skeleton, the outward manifestations are limited until late in the disease, when irreversible stiffening (ankylosis) and sometimes deformation progressively limit physical function and lead to disability. Society has little patience for patients with AS where so many people have complaints in the lower back area, and the insidious nature of AS allows patients to stay active participants in society for a very long time. However, the rapid uptake of biological agents, the first truly effective treatment beyond non-steroidal anti-inflammatory drugs revealed a large unmet need to alleviate the suffering caused by pain and stiffness.

The Outcome Measures in Rheumatology (OMERACT) initiative started in 1992 with a consensus conference on rheumatoid arthritis (RA) outcome measures, but very early on scientists involved in the care of patients with AS spun off as an independent group to develop a core set of domains to measure in AS. This spin off was called ASAS (Assessment of SpondyloArthritis international Society), and its results were first presented at OMERACT 4. Since then, the group has comprised a tightly integrated and highly motivated group of clinical researchers, independently producing first-class material in the area of outcome measurement, whilst remaining closely linked to OMERACT, both through adoption of OMERACT methodology and by bringing ASAS results to the OMERACT meetings for endorsement. It is no exaggeration to say that the development of AS as an indication for biological treatment was greatly speeded up by the work of ASAS on measurement methodology.

Science is never done, so ASAS justifiably went about improving what is available: in this issue of the Annals ASAS presents the first step in the development of …