Inflammatory back pain (IBP) is highly suggestive of inflammation in sacroiliac joints and spine. Missing the diagnosis of IBP in routine clinical practice leads to a prolonged delay in the diagnosis of axial spondyloarthritis (axSpA). The prevalence of AS in India is about 0.7-0.9/1000 population as per available studies. The prevalence of IBP in the general population is around 3-8% in the US and UK, however, the prevalence of spondyloarthritis is around 0.9%-1.4%. It means that not all IBP patients have axSpA. Similarly, the estimation of IBP is also affected by the criteria used for confirmation.

The concept of inflammatory back pain (IBP) describes a cohort of patients with chronic back pain, who have distinct clinical characteristics. Any back pain in younger patients (below 45 years) needs evaluation for axSpA, unless trauma is the reason. Low back pain worse at night suggests inflammatory disease or bony metastasis. Bilateral sacral pain, with radiation to both the buttocks, worse at night, better as the day goes is highly suggestive of IBP. Back pain in association with psoriasis, uveitis or colitis needs focused investigations for sacroiliitis.

IBP is an important feature of axSpA, but this is not the only possibility. IBP may also be present in other seronegative spondyloarthropathies such as psoriatic arthritis, enteropathic arthropathy, juvenile idiopathic arthritis, and reactive arthritis. Spinal infections, spinal metastasis, spinal or pelvic osteoporotic fractures, spinal osteoarthritis, and DISH can mimic IBP.

Once IBP is identified, appropriate history and focused evaluation should be done to define articular and extra-articular manifestations of spondyloarthritis. Investigations should include inflammatory markers- CRP, ESR, HLA B27, MRI of the whole spine, and sacroiliac joints with STIR sequences. In the presence of extraarticular manifestations relevant specialty referrals should be considered. In summary, early recognition of IBP in the context of other clinical, laboratory, and imaging findings, will result in timely diagnosis of axSpA.
 

Suggested Readings:

1. Coath FL, Gaffney K. Inflammatory back pain: a concept, not a diagnosis. Curr Opin Rheumatol.2021;33(4):319-325.
2. Magrey MN, Danve AS, Ermann J, Walsh JA. Recognizing Axial Spondyloarthritis: A Guide for Primary Care. Mayo Clin Proc.2020;95(11):2499-2508.