Spondyloarthritis update: new insights regarding classifcation, pathophysiology, and management.

There has been a burgeoning interest in the spondyloarthritides (SpAs) due to a confluence of elements. Basic science research has provided new insight into the unique pathophysiology of synovium, enthesium, and bone, highlighting the important differences from rheumatoid arthritis (RA). Through collaborative research of international working groups, classification criteria for psoriatic arthritis (PsA) and ankylosing spondylitis (AS) have been developed or are being refined to aid characterization and diagnosis of SpAs and aid in research. These same working groups, under the umbrella of Outcome Measures in Rheumatology Clinical Trials (OMERACT), have developed domain core sets to be measured in clinical trials and registries, and which allow validation of reliable outcome measures. Both through clinical trials and observational data from national clinical registries, the relative effectiveness and safety of old and new therapies are being demonstrated. This has been particularly shown with long-term data on anti-TNF therapy. Newer anti-TNF therapies are being developed, as are treatments with different mechanisms of action in order to treat patients who do not have long-term effectiveness or develop side effects to older disease modifying therapy and anti-TNFs. International treatment recommendations have been or are being developed based on the evidence base from clinical trials.