- Open Access
Early differential diagnosis of ankylosing spondylitis among patients with low back pain in primary care
BMC Family Practice volume 21, Article number: 90 (2020)
Diagnosing and treating low back pain (LBP) is a worldwide major primary care challenge in which a differential diagnosis between non-specific LBP and conditions with a known pathology is essential for choosing the optimal treatment strategy. The time required for the diagnosis of a condition such as ankylosing spondylitis (AS) was previously found too long. However, a recently published paper by Bashir et al. found that distinct episodes of axial pain separated by more than 6 months seem more predictive than currently applied characteristics in reaching an early diagnosis of AS.
With a global one-month point prevalence of 23.2%, low back pain (LBP) is a major health challenge across cultures . LBP is the leading cause of work disability and years lived with disability (YLDs) worldwide [2, 3].
Clinical diagnosis of LBP based on the patients’ history and clinical examinations is the key initial assessment by the first-line assessor of LBP—often the general practitioner (GP). This triage determines the subsequent diagnostic workup and informs the future treatment plan for the patient, including involvements of allied health care providers and medical specialist referrals . The purpose of diagnostic triage of LBP is to allocate patients to one of three broad categories: specific spinal pathology (< 1% of cases), radicular syndrome (∼ 5–10% of cases), or non-specific LBP (90–95% of cases), where non-specific LBP is identified by the exclusion of the first two first categories . Most cases are, therefore, considered unrelated to specific known spinal abnormalities . Patients with LBP constitute a group with a large variation in the manifestations, possible bio-psycho-social causes, precipitating and maintaining factors, course, and prognosis . Most patients with LBP appear to follow a particular pain trajectory over long periods and do not have frequently recurring or widely fluctuating patterns . However, a subgroup constituting 13% of patients can be classified as having a fluctuating pain trajectory . Patients belonging to the fluctuating pain trajectory show small improvements in functional capability . Furthermore, their psychological status is without improvement after 12 months, with the proportion of patients classified as depressed remaining constant (27–30%). Almost half had experienced pain for more than 3 years, and a third was still consulting their general practitioner about back pain at the 12-month follow-up . A newly published paper by Bashir et al. provides findings that might explain why patients with non-specific fluctuating pain have worse prognoses compared to patients with non-specific constant pain .
Ankylosing Spondylitis (AS) is considered a relatively rare diagnosis in general practice . However, in populations such as in the UK, with a high proportion of HLA-B27 positive in the population, the prevalence of AS among patients with LBP is up to 5% . AS is a condition with a long time between an initial consultation for LBP before receiving an AS diagnosis . The diagnostic delay in AS has previously been found unacceptably long, with females, younger patients, HLA-B27 negative, or patients with psoriasis having the longest diagnostic delay . Early symptoms of AS besides LBP are stiffness and fatigue. These are considered non-specific symptoms and are similar to symptoms reported among patients with non-specific LBP . Other diagnostic characteristics of AS, such as pain in the second half of the night and relief of pain and stiffness by exercise, are also often reported by patients with non-specific LBP [4, 15]. Nonsteroidal anti-inflammatory drugs can provide pain relief of AS, but no established diagnostic serum biomarkers allow the identification of AS in patients with early LBP .
Among the large group of patients with non-specific LBP, recent studies have found fear avoidance and other psychosocial factors predictive of worse outcomes when experiencing LBP [17, 18]. While including these factors in diagnostic screening tools provides some diagnostic information, it is important to stress the potential for misclassification of patient risk when using the available screening tools , thus making the clinical difference between non-specific LBP and AS hard to detect, which can increase delay for correct diagnosis.
Good early predictors for AS have previously been difficult to identify . However, a newly published paper, including 74 patients with AS, concluded that distinct episodes of axial pain separated by more than 6 months are frequently observed before an AS diagnosis . These episodes of pain among patients with LBP are highly associated with later receiving an AS diagnosis (OR 12.7, 95% CI 4.7 to 34.6) . Among patients later diagnosed with AS, recurrent episodes of LBP were an even more frequent finding than either large joint symptoms or tendon symptoms . In this new study, distinct episodes of axial pain separated by more than 6 months seem more predictive than currently applied characteristics in reaching an early diagnosis of AS . However, these findings need to be duplicated in future research including larger study populations.
A newly published paper found that two distinct periods of axial pain is predictive of receiving an AS diagnosis. This can support clinicians in reaching earlier diagnoses of AS among patients with non-specific pain, and this finding is important to inform future research into the differential diagnosis of patients with fluctuating non-specific LBP.
Availability of data and materials
Low back pain
Burton AK, Müller G, Balagué F, Cardon G, Eriksen HR, Hänninen O, et al. On behalf of the cost b13 working group on guidelines for prevention in low back pain. chapter 2 european guidelines for prevention in low back pain. Eur Spine J. 2006;15(Suppl 2):S136–68.
Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990–2010: a systematic analysis for the global burden of disease study 2010. Lancet. 2012;380(9859):2163–96.
Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, et al. The global burden of low back pain: estimates from the global burden of disease 2010 study. Ann Rheum Dis. 2014;73:968–74.
Low back pain and sciatica in over 16s: assessment and management. NICE guideline [NG59]. 2016. Available at https://www.nice.org.uk/guidance/ng59.
Bardin LD, King P, Maher CG. Diagnostic triage for low back pain: a practical approach for primary care. Med J Aust. 2017;206(6):268–73.
Buchbinder R, van Tulder M, Öberg B, Costa LM, Woolf A, Schoene M, Croft P, Lancet Low Back Pain Series Working Group. Low back pain: a call for action. Lancet. 2018;391(10137):2384–8.
Vlaeyen JWS, Maher CG, Wiech K, Van Zundert J, Meloto CB, Diatchenko L, et al. Low back pain. Nat Rev Dis Prim. 2018;4:52.
Dunn KM, Campbell P, Jordan KP. Long-term trajectories of back pain: cohort study with 7-year follow-up. BMJ Open. 2013;3(12):e003838.
Dunn KM, Jordan K, Croft PR. Characterizing the course of low back pain: a latent class analysis. Am J Epidemiol. 2006;163(8):754–61.
Bashir MT, Iversen L, Burton C. Clinical features in primary care electronic records before diagnosis of Ankylosing spondylitis: a nested case-control study. BMC Fam Practice. In Press.
Hamilton L, Macgregor A, Toms A, Warmington V, Pinch E, Gaffney K. The prevalence of axial spondyloarthritis in the UK: a cross-sectional cohort study. BMC Musculoskelet Disord. 2015;16:392.
Sykes MP, Doll H, Sengupta R, Gaffney K. Delay to diagnosis in axial spondyloarthritis: are we improving in the UK? Rheumatology (Oxford). 2015;54(12):2283–4.
Redeker I, Callhoff J, Hoffmann F, Haibel H, Sieper J, Zink A, Poddubnyy D. Determinants of diagnostic delay in axial spondyloarthritis: an analysis based on linked claims and patient-reported survey data. Rheumatology (Oxford). 2019;58(9):1634–8.
Nice guidelines. National Institute for Health and Care Excellence: Clinical Guidelines. Spondyloarthritis in over 16s: diagnosis and management. London: National Institute for Health and Care Excellence (UK). Available at: https://www.nice.org.uk/guidance/ng65.
van Hoeven L, Luime J, Han H, Vergouwe Y, Weel A. Identifying axial spondyloarthritis in Dutch primary care patients, ages 20-45 years, with chronic low back pain. Arthritis Care Res (Hoboken). 2014;66(3):446–53.
Turina MC, Yeremenko N, van Gaalen F, van Oosterhout M, Berg IJ, Ramonda R, et al. Serum inflammatory biomarkers fail to identify early axial spondyloarthritis: results from the SpondyloArthritis caught early (SPACE) cohort. RMD open. 2017;3(1):e000319.
Riis A, Karran EL, Thomsen JL, Jørgensen A, Holst S, Rolving N. The association between believing staying active is beneficial and achieving a clinically relevant functional improvement after 52 weeks: a prospective cohort study of patients with chronic low back pain in secondary care. BMC Musculoskelet Disord. 2020;21(1):47.
Fujii T, Oka H, Takano K, Asada F, Nomura T, Kawamata K, Okazaki H, Tanaka S, Matsudaira K. Association between high fear-avoidance beliefs about physical activity and chronic disabling low back pain in nurses in Japan. BMC Musculoskelet Disord. 2019;20(1):572.
Karran EL, McAuley JH, Traeger AC, Hillier SL, Grabherr L, Russek LN, Moseley GL. Can screening instruments accurately determine poor outcome risk in adults with recent onset low back pain? A systematic review and meta-analysis. BMC Med. 2017;15(1):13.
Walsh JA, Pei S, Penmetsa GK, Leng J, Cannon GW, Clegg DO, et al. Cohort identification of axial spondyloarthritis in a large healthcare dataset: current and future methods. BMC Musculoskelet Disord. 2018;19(1):317.
None of the authors received external funding for writing this paper.
Ethics approval and consent to participate
Consent for publication
AR is an associate editor for BMC Family Practice. The other authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
About this article
Cite this article
Riis, A., Olesen, J.L. & Thomsen, J.L. Early differential diagnosis of ankylosing spondylitis among patients with low back pain in primary care. BMC Fam Pract 21, 90 (2020). https://doi.org/10.1186/s12875-020-01161-6
- Early diagnosis
- Spondylitis Ankylosing
- Low Back pain
- Primary health care