Higher inflammatory burden than previously anticipated

Axial inflammation seen in people with early peripheral spondyloarthritis, but not predictive of relapse in those achieving remission.

Spondyloarthritis (shortened to SpA) refers to a spectrum of related rheumatic diseases caused by chronic inflammation. Many people with spondyloarthritis also have non-joint symptoms, such as psoriasis of the skin and nails, inflammatory bowel disease and eye problems.

The type of spondyloarthritis is defined according to what symptoms people have. Axial spondyloarthritis (axSpA) typically affects the spine and sacroiliac joints (where the spine meets the pelvis). Peripheral spondyloarthritis (pSpA) mostly involves joints and tendons in the arms and legs rather than the back. In this study, people who had their pSpA symptoms for less than 12 weeks were defined by the authors as having very early pSpA.

The authors wanted to see whether there was any evidence of axial disease in the sacroiliac joints and spine of people diagnosed with early pSpA. Axial disease in this case means inflammation of SIJs or spine, without causing back pain or stiffness in the back. They also wanted to see whether having axial inflammation could be used to predict whether people’s peripheral symptoms would get worse again after treatment was stopped.

The study looked at 56 people with newly diagnosed, very early pSpA who were taking part in the CRESPA
(Clinical Remission in Peripheral Spondyloarthritis) trial. Everyone was over the age of 18 and had experienced peripheral symptoms for less than 12 weeks.

CRESPA was a trial of a biologic medicine called golimumab. The trial was set up to see whether early treatment would allow drug-free remission. Remission was defined as defined as the absence of arthritis, enthesitis and dactylitis at two study visits 12 weeks apart. At the start of the trial, everyone had an MRI scan to look at their spine and sacroiliac joints. A second MRI was done when people achieved sustained clinical remission. Golimumab treatment was withdrawn at this time point to explore the possibility of drug-free remission.

The authors for this study used the MRIs taken in the CRESPA trial to see if people with very early pSpA had any evidence of axial inflammation before they were treated.

The main finding was that over one-third of people (36%) with early pSpA also had axial abnormalities visible on the first MRI taken. Interestingly, there was no association between axial involvement and back pain symptoms. Mostly the axial inflammation was in the sacroiliac joints, although a small number of people also had spinal involvement. For people who achieved clinical remission with golimumab treatment, the second MRI showed that there was also improvement in the sacroiliac joints.

On clinical remission, there were no significant differences in sacroiliac joint involvement between people who relapsed and those who were able to maintain remission after stopping treatment. This means that finding evidence of sacroiliac joint involvement on an MRI image at the time of clinical remission in people with early pSpA does not predict who will relapse.

Yes, this is the first study to use MRIs to look at axial involvement of the sacroiliac joint and spine in people with early pSpA. In addition, this is the first study to assess the clinical significance of axial involvement in people defined as having peripheral disease, by using this information to try to predict relapse after treatment discontinuation.

These findings indicate a much broader inflammatory burden than suspected, with an important overlap
between people defined as having either axial or peripheral SpA. These results might be important for understanding the value of screening for subclinical sacroiliac joint inflammation to help diagnosis in people suspected of having pSpA.

A limitation of the study was that MRIs were not done in people who did not achieve clinical remission. It would have been useful to have been able to compare the images between these two groups, but this was not a part of the original CRESPA trial.

Currently, there is a lot of scientific interest in being able to detect axial involvement in people with psoriatic arthritis – another type of spondyloarthritis. The authors plan to investigate this using whole-body MRI. It will be interesting to evaluate the effect of psoriatic arthritis treatment on axial inflammation, as a lot of biologic medicines with different modes of action are available. Future studies might also take a deeper look into the clinical significance of axial inflammation in people with pSpA by assessing treatment response and outcomes in a larger group of patients.

If you have newly diagnosed pSpA – or if you have peripheral joint inflammation but have not been diagnosed with SpA – you could also have underlying disease in your spine or sacroiliac joints. Your doctor may do an MRI to rule out axial involvement. If you have back pain or stiffness, it is important that you talk to your doctor.

If you have any questions or concerns about your disease or its treatment, speak to your doctor.

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Date prepared: December 2020
Summary based on research article published on: 28 October 2020
From: Renson T, et al. Axial involvement in patients with early peripheral spondyloarthritis: a prospective MRI study of sacroiliac joints and spine. Ann Rheum Dis 2021;80:103–108.doi:10.1136/annrheumdis-2020-218480

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