Axial spondyloarthritis – What is axSpA and how does it relate to Ankylosing Spondylitis?

Axial spondyloarthritis, non-radiographic spondyloarthritis, spondyloarthropathies… What exactly does it all mean? Understanding the terminology can be pretty confusing, especially as doctors and other healthcare professionals have recently changed the way that these conditions are characterised, so the same terms may not always be used consistently.

Essentially, spondyloarthropathies are a family of rheumatological conditions sharing clinical, radiographic and genetic factors, involving both the joints and potentially other bodily systems; including axial spondyloarthritis but also other conditions such as psoriatic arthritis and enteropathic spondyloarthropathy (associated with Crohn’s or ulcerative colitis). When conditions such as psoriasis, inflammatory bowel disease and uveitis occur in someone with axial spondyloarthritis, these are described as extra-articular manifestations (EAMs).

Where does Ankylosing Spondylitis fit in?

Currently, there is a move towards using axial spondyloarthritis (axSpA) as the main diagnostic term; with non-radiographic axial spondyloarthritis (nr-axSpA) and Ankylosing Spondylitis (AS) currently thought to be part of the same spectrum. The term ‘AS’ is then used to describe axSpA when clear structural changes can be seen on an x-ray; meanwhile ‘nr-axSpA’ can be used to describe axSpA whereby clear structural changes are not found on an x-ray, but instead may be diagnosed from other clinical features and potentially magnetic resonance imaging (MRI) results. While we are still unsure regarding the natural history of axSpA, it is clear that not all people with nr-axSpA go on to develop structural changes detectable by x-ray. However, it is worth noting that the people more likely to progress radiographically may be smokers, male, HLA-B27 positive, and have higher baseline levels of structural changes or CRP/ESR (see 2018 review by Sari & Haroon for details: https://link.springer.com/article/10.1007%2Fs11926-018-0795-4). It is important to note that the cut-off between nr-axSpA and AS is arbitrary, and burden of disease can be similar for both people with nr-axSpA and people with AS.

To understand the move towards using axSpA as the common term, it may be useful to understand the history of disease diagnosis.

History of axSpA

Historically, x-rays were an important part of diagnosing AS; whereby diagnosis required evidence of significant radiographic changes. This therefore led to long delays from symptom onset to diagnosis. Furthermore, as touched upon previously, many people with nr-axSpA may never develop the level of radiographic change that would have been previously required for a diagnosis of AS, so these diagnoses would have previously been missed, despite often displaying symptoms and disability consistent with AS. With advances in MRI and detection of early inflammatory changes of the spine and sacroiliac joints prior to structural changes, the Assessment for Spondyloarthritis International Society (ASAS) developed validated criteria for axSpA for use in research studies – allowing someone with chronic back pain to be classified as having axSpA via non-imaging clinical routes as well as through imaging. Although these criteria were developed for research studies, they have facilitated earlier diagnosis of axSpA in clinical practice and importantly, have allowed for earlier treatment of the condition.

Despite this, the average delay from axSpA symptom onset to diagnosis is still 8.5 years in the UK, which simply isn’t good enough. There has recently been a massive push to try and reduce this delay, raise awareness of axSpA amongst healthcare professionals and the general public, and facilitate earlier treatment. In fact, in 2017 the National Institute for Health and Care Excellence (NICE) published a guideline setting out recommendations for the diagnosis and management of axSpA; with a NICE Quality Standard later published in 2018. This year, the National Ankylosing Spondylitis Society (NASS – soon to be National Axial Spondyloarthritis Society) has furthermore launched the first All-Part Parliamentary Group (APPG) for axSpA – working with parliamentarians to put pressure on healthcare providers to ensure that the NICE guidelines are implemented in full. The APPG forms part of the wider NASS campaign Every Patient, Every Time, which is working towards every patient receiving an early diagnosis and effective care (see the Back Pain Plus campaign aiming to increase referral from secondary care https://nass.co.uk/get-involved/campaign-with-us/back-pain-plus/, in addition to the NASS allies partnership https://nass.co.uk/get-involved/campaign-with-us/nass-allies/ and the Asipiring to Excellence campaign https://nass.co.uk/aspiring-to-excellence/ – a UK-wide initiative to create a Rheumatology service network that is aspiring to excellence). Stay up to date with Every Patient, Every Time on the NASS website: https://nass.co.uk/news/every-patient-every-time/.

International Quality Standards

Most recently on the 11th October, on an international level, ASAS published their quality standards to improve the quality of health and care services for patients with axSpA worldwide. Whereby, once again, early referral was recognised as an important gap in care. In addition to referral, four other priority areas were defined for quality of care improvement: rheumatology assessment, treatment, education/self-management and comorbidities. These of course echo topics outlined in the NICE quality standard, despite lack of idea exchange between groups.

Development and implementation of these quality standards, in addition to an increasing awareness of axSpA among the public and healthcare professionals, will hopefully lead to improved diagnosis and treatment, to reduce the impact of the condition and improve quality of life. We hope that through dissemination of Project Nightingale results, this current study can also play a small part in increasing axSpA awareness.