Friday, 11 July 2014

Not all back pain is the same

Not all back pain is the same

In the last 10 years, much progress has been made in defining chronic low back pain (CLBP).  CLBP is defined as back pain > 3 months duration. There are 2 different types of CLBP, namely inflammatory and mechanical back pain. This takes into account the exclusion of CLBP with red flags or sinister features. Inflammatory back pain (IBP) is known to be a presenting feature of ankylosing spondylitis (AS). AS is a chronic inflammatory arthritis with predominant involvement of the spine resulting in inflammation of joints, in particular the sacroiliac (SI) joints.

I wanted to take some time to appreciate the papers from the beginning of the last decade (from 2004) which has highlighted the features and use of IBP identification. IBP is part of the new classification of the spondyloarthritides (SPA) by the Assessment of SpondyloArthritis International Society (ASAS)1. SPA is a group of inflammatory conditions with AS being the characteristic clinical condition.

            On average it takes 8.5 years for the diagnosis of AS to be made. It is important that patients with IBP are detected early and referred for further investigation and treatment. IBP is the leading symptom for axial SPA and is present in 70% of patients with SPA2. The features of IBP are 3,4.

Inflammatory back pain (if 4 out of 5 features are present)5
  1. Age of onset < 45 years
  2. Insidious onset
  3. Improvement  with exercise
  4. No improvement with rest
  5. Pain at night (with improvement on getting up)
                       
SPA affecting the spine (axial SPA) is present in 5% of patients with CLBP6.  If IBP is present, the likelihood of axial SPA goes up from 5% to 14%. On the other hand, if IBP is absent, the likelihood of axial SPA falls to less than 2%7. This is an important point as IBP alone is not enough to make a diagnosis of axial SPA. To reach a high enough probability of axial SPA (that is > 90%), other clinical features are needed 8.

The features of axial SpA that should be identified include clinical features, laboratory tests (eg. HLA-B27) and radiological imaging (eg. MRI). The clinical features that may point towards axial SPA include a good response to NSAIDs within 48 hours, uveitis, family history and peripheral arthritis9,10. When patients have IBP, the presence of 3 or more features of SPA increases the likelihood of definite axial SPA (80-95%). If 1 or 2 additional features of SPA are present, then the likelihood of axial SPA is lower between 35-70%7, 11. When IBP, clinical, laboratory and radiological factors are brought together, the sum of the presence of each factor can be calculated to give the probability of definite axial SPA12. This will mean a better and quicker way to make a diagnosis of axial SPA and better outcome for patients.

The identification of IBP in patients presenting to their general practitioners (GPs) in primary care with CLBP is the first step towards further assessment and investigations of axial SPA. Education of GPs and physiotherapists who see patients in primary care is important. On the 29th May 2014, I ran a Back Pain Seminar in Reading which was attended by over 70 GPs and physiotherapist. The focus was on the importance of identifying IBP in patients with CLBP. Patients with IBP can then be assessed for any clinical features associated with SPA and referred for any relevant investigations. This will help reduce the delay in diagnosing axial SpA and ankylosing spondylitis.

The Faculty (L-R): Berit Sund (organiser), Sally Dickinson, Claire Harris, Dr. Antoni Chan, Susan Hicks, Claire Jeffries

Sally Dickinson from the National Ankylosing Spondylitis Society (NASS) giving an update on the role of NASS

References
1.        Sieper J, Rudwaleit M, Baraliakos X, et al. The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis. Ann Rheum Dis. 2009;68 Suppl 2:ii1-44. doi:10.1136/ard.2008.104018.
2.        Dougados M, van der Linden S, Juhlin R, et al. The European Spondylarthropathy Study Group Preliminary Criteria for the Classification of Spondylarthropathy.; 1991:1218-1227. doi:10.1002/art.1780341003.
3.        Rudwaleit M, van der Heijde D, Landewé R, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis. 2009;68(6):777-83. doi:10.1136/ard.2009.108233.
4.        Rudwaleit M, Metter A, Listing J, Sieper J, Braun J. Inflammatory back pain in ankylosing spondylitis: a reassessment of the clinical history for application as classification and diagnostic criteria. Arthritis Rheum. 2006;54(2):569-78. doi:10.1002/art.21619.
5.        Sieper J, van der Heijde D, Landewé R, et al. New criteria for inflammatory back pain in patients with chronic back pain: a real patient exercise by experts from the Assessment of SpondyloArthritis international Society (ASAS). Ann Rheum Dis. 2009;68(6):784-8. doi:10.1136/ard.2008.101501.
6.        Underwood MR, Dawes P. Inflammatory back pain in primary care. Br J Rheumatol. 1995;34(11):1074-7. Available at: http://www.ncbi.nlm.nih.gov/pubmed/8542211.
7.        Rudwaleit M, van der Heijde D, Khan M a, Braun J, Sieper J. How to diagnose axial spondyloarthritis early. Ann Rheum Dis. 2004;63(5):535-43. doi:10.1136/ard.2003.011247.
8.        Rudwaleit M, Khan M a, Sieper J. The challenge of diagnosis and classification in early ankylosing spondylitis: do we need new criteria? Arthritis Rheum. 2005;52(4):1000-8. doi:10.1002/art.20990.
9.        Sieper J, Rudwaleit M. Early referral recommendations for ankylosing spondylitis (including pre-radiographic and radiographic forms) in primary care. Ann Rheum Dis. 2005;64(5):659-63. doi:10.1136/ard.2004.028753.
10.     Rudwaleit M, Sieper J. Referral strategies for early diagnosis of axial spondyloarthritis. Nat Rev Rheumatol. 2012;8(5):262-8. doi:10.1038/nrrheum.2012.39.
11.     Brandt HC, Spiller I, Song I-H, Vahldiek JL, Rudwaleit M, Sieper J. Performance of referral recommendations in patients with chronic back pain and suspected axial spondyloarthritis. Ann Rheum Dis. 2007;66(11):1479-84. doi:10.1136/ard.2006.068734.
12.     Feldtkeller E, Rudwaleit M, Zeidler H. Easy probability estimation of the diagnosis of early axial spondyloarthritis by summing up scores. Rheumatology (Oxford). 2013;52(9):1648-50. doi:10.1093/rheumatology/ket176.

@synovialjoints

Views are my own. These are opinions and cannot replace the need to see your physician for review of your individual medical condition.



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