Diagnosis and Classification of Spondyloarthropathies

Original Editor - Jess Bell Top Contributors - Jess Bell, Kim Jackson, Ewa Jaraczewska and Tarina van der Stockt

Introduction[edit | edit source]

Spondyloarthropathy is a chronic form of inflammatory arthritis. It is considered a common condition, but there is significant variation in the reported prevalence rates of spondyloarthropathy and its subgroups. There is also variation in estimated prevalence across geographical regions.[1] Stolwijk et al.[2] note that incidence rates of spondyloarthropathy range from 0.48 and 63/100.000, and prevalence rates range from 0.01 and 2.5%.

Spondyloarthropathies are "distinct from rheumatoid arthritis but are as important to recognise and manage early in their presentation to improve health outcomes."[3]

Spondyloarthropathy is un umbrella term for a family of diseases, which includes axial spondyloarthritis (also known as ankylosing spondylitis), psoriatic arthritis, reactive arthritis, enteropathic arthritis and undifferentiated arthritis. Individuals with undifferentiated arthritis "generally have an asymmetrical oligoarticular (fewer than 5 involved joints) arthritis, often involving the knees."[3] The majority of people with spondyloarthropathies have psoriatic arthritis or axial spondyloarthritis.[3] These conditions affect the axial and peripheral skeleton and have various extra-articular features, including:[4][5][6]

  • acute anterior uveitis
  • inflammatory bowel disease
  • psoriasis
  • enthesitis
  • dactylitis

Because spondyloarthropathies are a group of systemic inflammatory conditions, individuals with these conditions may have a heightened risk for cardiovascular disease[3] and other co-morbidities such as osteoporosis and depression. They also tend to result in reduced physical activity.[6]

For more information, please see Co-morbidities and Extra-articular Manifestations of Spondyloarthropathy.

Diagnosis of spondyloarthropathy is a complex process and must be given by a specialist (i.e. a rheumatologist).[7] However, because of the complexities in identifying these conditions, diagnosis is often delayed.[8] Axial spondyloarthritis often goes undiagnosed for five to ten years from symptom onset.[9] In the United Kingdom, there is a mean average of 8.7 years of delay between symptom onset and diagnosis.[10] Gregory et al.[10] note that this delay is due to a lack of:

  • healthcare professional and community awareness about axial spondyloarthritis
  • recognition
  • appropriate referral

These delays are significant because early diagnosis of axial spondyloarthritis results in better outcomes in terms of disease activity, function, spinal mobility and radiographic damage, as well as a better response to treatment.[8]

"Delayed diagnosis is associated with worse outcomes and poor treatment responses in [spondyloarthritis] patients. Physician and patient awareness of inflammatory back pain are essential for the early diagnosis of [spondyloarthritis]"[8]

Significantly, for physiotherapists, a prior diagnosis of mechanical back pain is an independent factor related to delayed diagnosis.[8] It is, therefore, necessary to differentiate between mechanical and inflammatory back pain. For more information on differentiating these types of pain, please click here.

Various classification systems exist to improve the early detection of spondyloarthropathy. This page will explore, in particular, the ASAS classification for axial spondyloarthritis, which classifies spondyloarthritis as either axial (radiographic or non-radiographic) or peripheral,[11] as well as the CASPAR criteria for psoriatic arthritis.

The following video provides insight from patients on the impact of delayed diagnosis of axial spondyloarthritis.

[12]

The next video discusses the diagnosis of inflammatory back pain from a medical perspective.

[13]

Axial Spondyloarthritis[edit | edit source]

Axial spondyloarthritis is the prototypic form of spondyloarthropathy.[7] The modified New York Classification Criteria (mNYCC) was previously used to diagnose axial spondyloarthritis.[4] The mNYCC includes clinical and radiological criteria:[14]

Radiological Criteria
The appearance of the sacroiliac joints on x-ray is given a grade of 0 to 4:
  • Grade 0 = normal
  • Grade 1 = suspicious changes
  • Grade 2 = minimal definite changes
  • Grade 3 = distinctive changes
  • Grade 4 = ankylosis (fusion of bones)
To meet the radiological criteria for axial spondyloarthritis, a patient has:

Grade 2, 3 or 4 sacroiliitis on both sides

OR

Grade 3 or 4 sacroiliitis on one side

As well as meeting the radiological criteria, the patient must fulfil at least one of the following clinical criteria:[14]

Clinical Criteria
  • Low back pain for at least three months, which is improved by exercise but not by rest
  • Limitation in the flexibility of the lumbar spine
  • Reduction in chest expansion

However, structural damage is estimated to take six to ten years to develop from symptom onset.[15] Sometimes, it may not develop at all.[16] Thus, the mNYCC is unable to detect patients with early signs of axial inflammation.[15] This has added to the delay in diagnosis of axial spondyloarthritis.[4][7]

ASAS Criteria[edit | edit source]

"The ASAS criteria [...] marked a major step forward in the spondyloarthritis research, distinguishing axial from peripheral forms and allowing earlier identification by the use of MRI. Prior to this, the prototypic role of axial spondyloarthritis [...] was merely found on x-ray only, that was the only way you could diagnose this condition. And of course x-ray changes, structural changes to the sacroiliac joints showing sclerosis or fusion of these joints we know now as later stage findings in the process, in the disease process. Because of this, we [...] would have missed many patients who hadn't yet got to that stage, or may never have got to the later stage, structural changes on x-ray, but certainly are now going to be captured given this new criteria."[7] -- Christopher Martey

The creation of the Assessment of Spondyloarthritis International Society Axial Spondyloarthritis (ASAS) classification criteria in 2009 has been considered a positive step forwards for research on spondyloarthropathy.[4][17] [18] This classification has, for the first time, enabled earlier identification of axial spondyloarthritis through magnetic resonance imaging (MRI).[4][19]

The ASAS also created another axial spondyloarthritis subgroup, non-radiographic spondyloarthritis (nrAxSpA). A diagnosis of nrAxSpA can be given to patients who fulfil certain clinical criteria but do not have radiographic sacroiliitis.[20]

It is, however, important to note that these criteria are not diagnostic in themselves. The clinician still needs to consider the whole picture.[7]

"When somebody uses this criteria, they need to look at the whole picture. The criteria itself tries to look at the history of the patient, how long they've had their back pain, what age they are, but also the differences around imaging and clinical findings."[7] -- Christopher Martey

The 2009 ASAS criteria essentially incorporate two arms, an imagining arm and a clinical arm. The criteria are as follows:[20]

Patients who have had back pain for more than three months, with an age of onset less than 45 years, as well as:
Imaging Arm OR Clinical Arm
Sacroiliitis on imaging (i.e. active (acute) inflammation on MRI that is highly suggestive of sacroiliitis or definite radiographic sacroiliitis according to mNYCC)

PLUS

One or more features of spondyloarthropathy

Positive HLA-B27

PLUS

Two or more features of spondyloarthropathy

ASAS features of spondyloarthropathy are [21]

  • Inflammatory back pain
  • Arthritis
  • Enthesitis (heel) (i.e. inflammation of the site where tendons/ligaments insert into bone)
  • Uveitis (inflammation of the uvea)
  • Dactylitis (whole digit swelling)
  • Psoriasis
  • Crohn’s / colitis
  • Good response to NSAIDs
  • Family history of spondyloarthropathy
  • HLA-B27 positive
  • Elevated CRP

Peripheral Spondyloarthritis[edit | edit source]

In 2011, the ASAS criteria were extended to better include peripheral manifestations of the disease.[22] Psoriatic arthritis, reactive arthritis, and enteropathic arthritis are largely considered peripheral conditions, although there may be some features that overlap with axial spondyloarthritis (radiographic and non-radiographic) and vice versa.[23] To be classified as having peripheral spondyloarthritis, a patient must have either:[22]

Arthritis OR enthesitis OR dactylitis, and fulfil one of the two following categories:
One or more of the following: OR Two or more of the following:
  • Uveitis
  • Psoriasis
  • Crohn's / ulcerative colitis
  • Preceding infection
  • HLA-B27 positive
  • Sacroillitis on imaging
  • Arthritis
  • Enthesitis
  • Dactylitis
  • Previous inflammatory back pain
  • Family history of spondyloarthritis

These criteria were found to have a sensitivity of 77.8 percent and a specificity of 82.9 percent.[22]

Psoriatic Arthritis[edit | edit source]

Psoriatic arthritis is a "chronic, inflammatory, musculoskeletal disease associated with psoriasis."[24] Ogdie et al.[24] note that up to 30% of individuals with psoriasis may develop psoriatic arthritis at some point in their life.

Like axial spondyloarthritis, diagnosing psoriatic arthritis is challenging,[25][26] and this condition is often underdiagnosed.[27] This is significant as even a short delay (six months) from initial symptoms to the first rheumatology appointment can affect long-term physical function.[25]

"Even a 6-month delay from symptom onset to the first visit with a rheumatologist contributes to the development of peripheral joint erosions and worse long-term physical function."[25]

While various classification systems have been used to identify psoriatic arthritis, the 2006 Criteria of the Classification of Psoriatic Arthritis (CASPAR)[28] has helped increase medical practitioners' recognition of this condition.[26] The CASPAR tool has been found to have a specificity of 98.7 percent and a sensitivity of 91.4 percent. The criteria is defined as follows:[28]

A patient must have an inflammatory articular disease (joint, spine or entheseal) PLUS fulfil three or more of the following five categories:
  1. Evidence of current psoriasis, a personal history of psoriasis or a family history of psoriasis
    • Current psoriasis is defined as psoriatic skin or scalp disease identified by a rheumatologist or dermatologist, which is present today
    • A personal history of psoriasis is defined as a history of psoriasis obtained from either the patient, family physician, dermatologist, rheumatologist, or other qualified health care provider
    • A family history of psoriasis is defined as a history of psoriasis in a first or second-degree relative, based on the patient report
2. Typical psoriatic nail dystrophy includes onycholysis, pitting and hyperkeratosis, which can be observed on physical examination
3. A negative test for rheumatoid factor
4. Either current dactylitis or a history of dactylitis
5. Radiographic evidence of juxta-articular new bone formation, which appears as poorly defined ossification near joint margins (excluding osteophyte formation) on hand or foot x-rays

NB: The presence of current psoriasis is assigned two points, while all other clinical features are given one point.

Recognition and Referral of Spondyloarthropathy[edit | edit source]

"I would implore you to make sure you are focused on spotting the signs early so we can try and get these patients an early diagnosis to help support their management and actually better manage and deal with a lifelong condition."[7] -- Christopher Martey

A specialist diagnoses spondyloarthropathy, but physiotherapists need to be able to detect and refer patients who may present with concerning features to the appropriate services.

The "NICE Guidelines on Spondyloarthritis in over 16s" remind clinicians in cases of suspected spondyloarthropathy that:[3]

  • symptoms of spondyloarthritis can be diverse and challenging to identify
  • signs and symptoms may be musculoskeletal (i.e. inflammatory back pain, enthesitis, dactylitis) or extra-articular (i.e. uveitis, psoriasis)
  • risk factors include recent genitourinary infection and a family history of spondyloarthritis or psoriasis
  • axial spondyloarthritis affects a similar number of women as men
  • it can occur in individuals who are not HLA-B27 positive
  • it may be present even if there is no evidence of an x-ray

These guidelines recommend referral to a rheumatologist for suspected axial spondyloarthritis if a patient has had low back pain for more than three months that started before the age of 45 years as well as FOUR or more of the following criteria:[3]

  • low back pain that started before the age of 35 years - this increases the likelihood that the patient's back pain is due to spondyloarthritis when compared to low back pain that started between the age of 35 and 44 years
  • pain/symptoms that wake the patient during the second half of the night
  • buttock pain
  • pain that improves with movement
  • pain that improves within 48 hours of taking non-steroidal anti-inflammatory drugs (NSAIDs)
  • patients who have a first-degree relative with spondyloarthritis
  • patients who have current or past arthritis
  • patients who have current or past enthesitis
  • patients who have current or past psoriasis

If three of the additional criteria are present, NICE Guidelines recommend that an HLA‑B27 test is performed. If this test is positive, the patient would need to be referred to a rheumatologist for assessment.[3]

The full NICE Guidelines on when to refer patients with suspected spondyloarthropathy are available here.

Summary[edit | edit source]

  • While classification systems exist to aid the identification of spondyloarthropathy, there is no gold standard for diagnosing this family of conditions. Because of the complexities and variety of symptoms, diagnosis of these conditions can be lengthy and delayed.[7]
  • Classification systems such as ASAS and CASPAR can aid in the recognition / diagnosis of axial spondyloarthritis and psoriatic arthritis.
  • Delays in diagnosis are significant as they affect outcomes and result in poorer treatment responses.[8]
  • Diagnosis is made based on the patient’s history, clinical examination, laboratory tests, imaging, and an index of suspicion around spondyloarthropathy.[7]

References[edit | edit source]

  1. Stolwijk C, van Onna M, Boonen A, van Tubergen A. Global prevalence of spondyloarthritis: a systematic review and meta-regression analysis. Arthritis Care Res (Hoboken). 2016 Sep;68(9):1320-31.
  2. Stolwijk C, Boonen A, van Tubergen A, Reveille JD. Epidemiology of spondyloarthritis. Rheum Dis Clin North Am. 2012 Aug;38(3):441-76.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Spondyloarthritis in over 16s: diagnosis and management. London: National Institute for Health and Care Excellence (UK); 2017 Jun. PMID: 32049469.
  4. 4.0 4.1 4.2 4.3 4.4 Dubreuil M, Deodhar AA. Axial spondyloarthritis classification criteria: the debate continues. Curr Opin Rheumatol. 2017; 29(4): 317-322.
  5. Ehrenfeld M, Infection and spondyloarthropathies. In: Shoenfeld Y, Agmon-Levin N, Rose NR editors. Infection and autoimmunity. Elsevier B.V. 2015. p745-57.
  6. 6.0 6.1 Physiopedia. Co-morbidities and Extra-articular Manifestations of Spondyloarthropathy.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Martey C. Diagnosis and Classification of Spondyloarthropathies Course. Plus2020.
  8. 8.0 8.1 8.2 8.3 8.4 Seo MR, Baek HL, Yoon HH, Ryu HJ, Choi HJ, Baek HJ, Ko KP. Delayed diagnosis is linked to worse outcomes and unfavourable treatment responses in patients with axial spondyloarthritis. Clin Rheumatol. 2015; 34(8): 1397-405.
  9. Braun J, Sieper J. Early diagnosis of spondyloarthritis. Nature clinical practice rheumatology. October 2006 vol 2 no 10  : 2C
  10. 10.0 10.1 Gregory WJ, Kaur J, Bamford S, Tahir H. A survey of diagnostic delay in axial spondyloarthritis across two National Health Service (NHS) rheumatology services. Cureus. 2022 Mar 30;14(3):e23670.
  11. De Winter JJ, van Mens LJ, van der Heijde D, Landewé R, Baeten DL. Prevalence of peripheral and extra-articular disease in ankylosing spondylitis versus non-radiographic axial spondyloarthritis: a meta-analysis. Arthritis Res Ther. 2016; 18(1): 196.
  12. National Axial Spondyloarthritis Society. Ankylosing Spondylitis (axial spondyloarthritis) AS Getting your diagnosis. Available from: https://www.youtube.com/watch?v=_ojkHgiN3rQ [last accessed 16/11/2020]
  13. AJMCtv. Accurately Diagnosing Axial Spondyloarthritis. Available from https://www.youtube.com/watch?v=eRd3xAu9kYw&t=1s [last accessed 18/11/2020].
  14. 14.0 14.1 van der Linden S, Valkenburg HA, Cats A. Evaluation of diagnostic criteria for ankylosing spondylitis. Arthritis Rheum. 1984; 27(4): 361-8.
  15. 15.0 15.1 Deodhar A. Axial spondyloarthritis criteria and modified NY criteria: issues and controversies. Clin Rheumatol. 2014; 33(6): 741-7.
  16. Mease PJ, Heijde DV, Karki C, et al. Characterization of Patients With Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis in the US-Based Corrona Registry. Arthritis Care Res (Hoboken). 2018; 70(11): 1661-1670.
  17. Poddubnyy D. Classification vs diagnostic criteria: the challenge of diagnosing axial spondyloarthritis. Rheumatology. 2020 Oct;59(Supplement_4):iv6-17.
  18. Lindqvist E, Olofsson T, Jöud A, Geijer M, Wallman JK, Mogard E. How good is the agreement between clinical diagnoses and classification criteria fulfilment in axial spondyloarthritis? Results from the SPARTAKUS cohort. Scandinavian Journal of Rheumatology. 2022 Jun 12:1-0.
  19. Meunier R, Truchetet ME, Dallaudière B, Fournier C, Barnetche T, Amoretti N, Cornelis F, Hauger O. MRI and spondyloarthropathy: diagnostic performance compared to long-term clinical follow-up with an evaluation of gadolinium chelates injection. European Radiology. 2022 Mar;32(3):1409-18.
  20. 20.0 20.1 Slobodin G, Eshed I. Non-Radiographic Axial Spondyloarthritis. Isr Med Assoc J. 2015; 17(12): 770-6.
  21. Truong SL, McEwan T, Bird P, Lim I, Saad NF, Schachna L, Taylor AL, Robinson PC. Australian Consensus Statements for the Assessment and Management of Non-radiographic Axial Spondyloarthritis. Rheumatol Ther. 2022 Feb;9(1):1-24.
  22. 22.0 22.1 22.2 Rudwaleit M, van der Heijde D, Landewé R, Akkoc N, Brandt J, Chou CT, Dougados M, et al. The Assessment of SpondyloArthritis International Society classification criteria for peripheral spondyloarthritis and spondyloarthritis in general. Ann Rheum Dis. 2011; 70(1): 25-31.
  23. Hauk L. Spondyloarthritis: NICE Releases Guidelines on Diagnosis and Treatment. Am Fam Physician. 2017; 96(10): 677-678.
  24. 24.0 24.1 Ogdie A, Coates LC, Gladman DD. Treatment guidelines in psoriatic arthritis. Rheumatology (Oxford). 2020 Mar 1;59(Suppl 1):i37-i46.
  25. 25.0 25.1 25.2 Haroon M, Gallagher P, FitzGerald O. Diagnostic delay of more than six months contributes to poor radiographic and functional outcome in psoriatic arthritis. Ann Rheum Dis. 2015; 74(6): 1045-50.
  26. 26.0 26.1 Ocampo D V, Gladman D. Psoriatic arthritis. F1000Res. 2019; 8 :F1000 Faculty Rev-1665.
  27. Ogdie A, Coates LC, Gladman DD. Treatment guidelines in psoriatic arthritis. Rheumatology. 2020 Mar 1;59(Supplement_1):i37-46.
  28. 28.0 28.1 Taylor W, Gladman D, Helliwell P, Marchesoni A, Mease P, Mielants H; CASPAR Study Group. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum. 2006; 54(8): 2665-73.