No correlation exists between MRI findings and HLA-B27 positivity or the presence or duration of chronic back pain. Findings in the spine were more prevalent with increasing age, leading the authors to suggest degenerative changes were likely picked up on the MRIs.
Implications
The base article raises several questions. First, how important is it to detect nr-axSpA early? One study showed the progression from nr-axSpA to ankylosing spondylitis (AS)—meeting mNY imaging criteria—of 12% over two years with elevated C-reactive protein (CRP) level being the best predictor of progression.6
Another paper demonstrated that 50% of patients who initially met mNY criteria were reclassified as mNY-negative at their five-year follow-up, and 5% of nr-axSpA patients progressed to mNY-positive status.7 Thus, progression to AS appears slow, and even patients initially diagnosed with radiographic disease may have transient or subtle changes that are later deemed normal.
The next question: Does treating patients with nr-axSpA early improve outcomes? One randomized, controlled trial examined 80 patients with negative SI joint X-ray and inflammatory back pain, ≥2 SpA features and high Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores and found no difference between etanercept and placebo treatment after six months.8
Another trial (ABILITY-1) showed adalimumab was more effective in patients with nr-axSpA, with either positive CRP or sacroiliitis at 12 weeks. Most patients were also HLA-B27 positive.9
So what else can cause bone marrow edema? It’s well described in professional athletes, non-athletes exercising more aggressively (be careful with your New Year’s resolutions, y’all) and even post-partum women.10,11 Further, sarcoidosis, diffuse idiopathic skeletal hyperostosis, hyperparathyroidism, osteitis condensans ilii, Paget disease and infectious arthritis can mimic or cause sacroiliitis appearance on imaging and be wrongly diagnosed as SpA.11–14 Transient changes in SI joint are also detected in some reactive arthritis patients but require no treatment.12
Overdiagnosis of SpA can lead to missing other diagnoses, psychologic stress to patients, risk of litigation and high cost to patients and society.14 To address these issues, a new trial by Spondyloarthritis Research and Treatment Network (SPARTAN), called Classification of Axial Spondyloarthritis Inception Cohort (CLASSIC), aims to validate ASAS criteria with a more stringent definition of inflammation on MRI and independent review of all imaging studies with a five-year follow-up to be completed in 2024.15 To be discussed in RheumMadness 2025.
Chances in the Tournament
We think our team fares quite well in our region and the tournament overall. As rheumatologists, we are all painfully aware of how difficult the diagnosis of SpA can be, and we may become distracted by the other teams in the tournament with potentially excellent stats. There are animals sadly having human diseases, molecular biology galore and—the topic of every rheumatologist’s favorite consult—Increasing +ANA.
