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I read with great interest the study published by Renson et al.1 The authors concluded in the abstract that, ‘Our data reveal a need for a waiting period of at least 6 months to perform an MRI-SIJ in postpartum women with back pain’. But 69% of study subjects do not have back pain and are asymptomatic. Though the study is very systematically planned and has achieved its primary aim, the inferences drawn seem a little far-fetched and are applicable to only a limited set of individuals in real life. The fear of overdiagnosing spondyloarthritis (SpA) comes into the picture only when the dedicated sacroiliac joint (SIJ) is ordered, which may not be the case for most of the study population (69%) in real life. So, the study would have been more pragmatic if only subjects with chronic back pain 8/35 (22.85%) were included. Assessment of SpondyloArthritis international Society (ASAS) criteria mandate presence of ‘Inflammatory back pain’ for more than 3 months before proceeding to MRI-SIJ.2 So, only 4/35 (11.4%) would have qualified for imaging in real life. It would have been more useful had the authors compared Spondyloarthritis Research Consortium of Canada (SPARCC) scores in individuals with/without inflammatory back pain than just back pain. The number of individuals with ‘inflammatory back pain’ and the number of individuals showing sacroiliitis and positive SPARCC Score at 1 year are the same (4/35). Whether these are the same subjects or different should be looked into. Also, the data related to acute phase reactants, like C reactive protein, would have added value to the results and analysis.
The study definitely emphasises the importance of avoiding overdiagnosis of SpA based on incidental SIJ findings. But, delaying diagnosis in ‘true’ SpA can lead to the progression of disease, damage accrual and increased disability duration. As evident from the recent population-based study, individuals in the ‘imaging arm’ (positive findings on MRI) have faster progression from non-radiographic SpA to radiographic SpA. 3 Studies have also shown more delay in diagnosis for women than males.4 The reason for this is, in part, the classical teaching of higher male to female ratio in SpA. But a recent cohort study doesn’t show any gender difference.5 So, delaying imaging for 6 months altogether for all postpartum women with back pain seems unjust. Future studies comparing likelihood ratios with MRI findings alone and with the inclusion of inflammatory back pain, acute phase reactants, other SpA features, positive family history and response to non-steroidal anti-inflammatory agents would help us in finding ‘The right one’ who needs dedicated MRI-SIJ in the postpartum period.
Patient consent for publication
Contributors AAZ has designed and written the correspondence.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; internally peer reviewed.
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