A person with axial spondyloarthritis, as indicated by red pain sports on the spine/back pain, is placed i a light blue background Surrounding the person are various forms of TNF inhibitor biologics, including injections and infusions.
Credit: Tatiana Ayazo

Axial spondyloarthritis (axSpA) is form of inflammatory arthritis best known for causing chronic lower back pain. The disease often impacts the spine itself as well as the sacroiliac (SI) joints that connect the lower spine to the pelvis. Although axSpA tends to be progressive and degenerative, not everyone who has it takes disease-modifying medication. In fact, non-steroidal anti-inflammatories (NSAIDs), which ease inflammation but do not slow the progression of the condition, are often used as a first-line treatment, especially for patients who have the “non-radiographic form” of the disease.

Traditionally, axSpA has been divided into two sub-types: radiographic and non-radiographic. People with radiographic axSpA have damage to the spine or SI joints that is visible on an X-ray (radiograph), whereas those with non-radiographic axSpA do not.

Although some people with non-radiographic axSpA never progress to the radiographic form, delaying biologic disease-modifying therapy might be a mistake for members of either subgroup, according to recent research. A study presented at the EULAR 2021 Virtual Congress, the annual meeting of the European Alliance of Associations for Rheumatology, suggests that patients with either form of axSpA might fare better if they start a biologic as soon as possible — although it can take more than two years to see proof that it’s helping.

For the study, researchers analyzed the “sacroiliitis scores” of 301 participants from the ongoing German Spondyloarthritis Inception Cohort. The sacroiliitis score is a numeric “grade” assigned to axSpA patients to determine the severity of their sacroiliac joint inflammation. The researchers focused on patients who had X-rays taken two years apart. When the study began, 166 of participants had been living with non-radiographic axSpA for five years or less; the remaining 135 had been living with radiographic axSpA for 10 years or less.

Initially, only nine patients in the study were using a tumor necrosis factor (TNF) inhibitor, such as adalimumab (Humira) or etanercept (Enbrel), but that number grew to 87 patients during the study. These medications are typically prescribed to axSpA patients after first-line treatments, like NSAIDs, are not working well enough to control symptoms.

The researchers found that patients who had used a TNF inhibitor for at least 12 months during the previous two-year period had lower changes in their sacroiliitis score than those did not receive TNF inhibitors during the same previous two-year period.

The treatment was associated with slowing down erosion of bone in the sacroiliac joint.

However, when researchers looked at the current two-year period, comparing people who had been taking biologics for at least 12 months to those who had not, they did not observe the same decrease in the sacroiliitis progression score in those on therapy.

The authors concluded that using TNF medication early in the disease process is associated with slowing the rate of deterioration of the SI joints in axSpA patients, but the effect only became evident two to four years after starting treatment.

“The data indicate that TNF inhibitors have a late effect,” study author and rheumatology researcher Murat Torgutalp said in the Eular Congress News. “You cannot observe the effect of TNF inhibition on radiographic progression in the same interval [shortly after that treatment is started]. You have to wait to see this in the next interval.”

Since axSpA is a chronic disease that currently has no cure and that patients can have for the rest of their lives, it’s important for patients and doctors to understand not only whether therapies can help prevent disease progression, but to also have realistic expectations about timing and how long it takes to see such a benefit.

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Poddubnyy D, et al. Treatment of Axial Spondyloarthritis: What Does the Future Hold? Current Rheumatology Reports. July 20, 2020. doi: https://doi.org/10.1007/s11926-020-00924-5

TNF Inhibitors Take Time to Slow Radiographic Progression in Axial Spa. EULAR Congress News. June 3, 2021. https://www.eularcongressnews-digital.com/eularcongressnews/eular_2021_thur_june_3/MobilePagedReplica.action?pm=1&folio=1#pg1.

Torgutalp M, et al. Tumor Necrosis Factor Inhibitors Show a Delayed Effect on Radiographic Sacroiliitis Progression in Patients with Early Axial Spondyloarthritis: 10-Year Results from the German Spondyloarthritis Inception Cohort. Annals of the Rheumatic Diseases. Volume 80, Supplement 1. 2021. doi: http://doi.org/10.1136/annrheumdis-2021-eular.2926.

Treatment with Tumor Necrosis Factor Inhibitors May Slow Disease Progression in Patients with Spondyloarthritis. Press Release. EULAR. June 4, 2021. https://www.eular.org/sysModules/obxContent/files/www.eular.2015/1_42291DEB-50E5-49AE-5726D0FAAA83A7D4/eular_press_release_op0137_v1_08may21_clean.pdf.

Tsoi C, et al. Imaging of sacroiliitis: Current status, limitations and pitfalls. Quantitative Imaging in Medicine and Surgery. February 2019. doi: https://doi.org/10.21037/qims.2018.11.10.

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