Jeff Stark, MD: Diagnosing nr-ax-SpA

In the field of rheumatology, it is uncommon to have formal diagnostic criteria, largely because of the heterogeneity of how the diseases often present.

Although there are no specific diagnostic criteria for nonradiographic axial spondyloarthritis (nr-ax-SpA), there are classification criteria to help guide diagnosis.

In a recent interview with HCPLive®, Jeff Stark, MD, head of medical immunology at UCB said classification criteria are used primarily for clinical trials to identify a patient population appropriate to study. The criteria contain pearls that can be used to inform the diagnostic process.

Sometimes rheumatologists look to the ASAS classification criteria published in 2009 that provides helpful diagnostic guidance to the community. A patient can meet the criteria by having imaging evidence of the disease, though patients with nr-ax-Spa don’t have demonstrable radiographic evidence, typically demanding an MRI rather than an x-ray. If a patient has imaging evidence and symptoms, it is possible to make a diagnosis.

Still, if a patient does not have imaging evidence, they may still have a genetic marker for the disease called HLAB27. The gene can be assessed by a blood test.

“These clinical features are well known to the community, but some of them, in actuality, affect other organ systems outside the musculoskeletal system,” Stark said.

Clinical manifestations such as uveitis, inflammatory bowel disease, and plaque psoriasis can cause patients to present to a provider other than a rheumatologist. There is still a great opportunity to inform other specialties about the way nr-ax-SpA may present in patients.