Non-Radiographic Axial Spondyloarthritis: A Review

Updates from the ACR Convergence 2023 Review Course, part 5

SAN DIEGO—Led by moderators Noelle Rolle, MBBS, assistant professor in the Division of Rheumatology, associate program director of the Rheumatology Fellowship at the Medical College of Georgia, Augusta University, and Julia Schwartzmann-Morris, MD, associate professor, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Great Neck, N.Y., the Review Course at ACR Convergence 2023 delivered on the promise of a thorough, thoughtful discussion of a plethora of subjects in rheumatology.

Dr. Ogdie-Beatty addressed a full room in the Review Course preceding the opening of ACR Convergence 2023.

Alexis Ogdie-Beatty, MD, MSCE, associate professor of medicine, associate professor of epidemiology, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, gave a presentation on non-radiographic axial spondyloarthritis (nr-axSpA).

nr-axSpA

It is estimated that about 1% of the U.S. population between ages 20 and 59 has axial spondyloarthritis (axSpA) and that peak incidence of the condition occurs in the second and third decades of life.¹ With regard to sex, nr-axSpA has a ratio of about 1:1 in males and females.²

When a rheumatologist is seeing a patient with back pain, it is important to get a sense of whether strong features of inflammatory back pain are present. Some of the features of this type of back pain include onset before age 45 and back pain/stiffness that is worse in the second half of the night and may awaken the patient from sleep.

Elevations in C-reactive protein (CRP) may be seen more commonly than elevations in erythrocyte sedimentation rate (ESR), but both inflammatory markers can be normal in patients with axSpA. Positivity for HLA-B27 can be helpful in raising the pre-test probability of axSpA in a patient with the right clinical symptoms, but it should be noted that fewer patients with nr-axSpA are HLA-B27 positive than patients with radiographic axSpA.

When radiographs of the sacroiliac joints are negative but clinical suspicion of axSpA remains high, magnetic resonance imaging (MRI) of the pelvis or sacrum is often indicated. On this topic, Dr. Ogdie-Beatty stressed that contrast is not needed for this type of MRI. Even MRI testing has its limits: Abnormalities can increase with age, and false positive findings can be seen in athletes, military recruits, and pregnant or recently pregnant patients.

axSpA vs. nr-axSpA

Speaking more broadly on the concept of radiographic vs. non-radiographic axSpA, Dr. Ogdie-Beatty explained that it was originally thought that non-radiographic disease progressed to radiographic disease over time. However, it is unclear if nr-axSpA represents an early stage of radiographic disease or if it is a different entity all together. Based on trends in the epidemiology of the conditions, it is expected that the proportion of patients with nr-axSpA will increase while that of patients with radiographic axSpA will decrease in future years.