Early AxSpA Diagnosis Stable in Most Referred Patients

MILAN, Italy — Most people with recent-onset chronic back pain who are referred to a rheumatologist and then diagnosed with definite axial spondyloarthritis (axSpA) maintain that diagnosis over the next 2 years, but for those with residual diagnostic uncertainty for axSpA, particular characteristics may help to identify those who will or will not go on to receive a definite diagnosis, according to presentations given at the European Alliance of Associations for Rheumatology (EULAR) 2023 Annual Meeting.

Although a rheumatologist's early axSpA diagnosis is reliable, new research also presented at the meeting reveals that the axSpA clinical phenotype presentation has great heterogeneity around the world, adding to the challenge.

These findings also dovetail with the consensus of an expert panel from the Assessment of SpondyloArthritis international Society (ASAS) that determined early axSpA should be defined by a duration of axial symptoms of less than 2 years, a move that should make research studies of early disease more consistent.

Diagnosis at First Sight

To help in overcoming the long diagnostic delay typically encountered by patients with axSpA, researchers involved in the longitudinal Spondyloarthritis Caught Early (SPACE) cohort have sought to measure the prevalence of axSpA and the reliability of an early diagnosis in patients with chronic back pain (CBP). SPACE researcher Mary Lucy Marques, MD, a rheumatologist at Coimbra Hospital and University Center, Coimbra, Portugal, and PhD student at Leiden University Medical Center, Leiden, the Netherlands, presented the main results of the study, which included patients younger than 45 years with CBP of unknown origin lasting 3 months to 2 years.

Dr Mary Lucy Marques

Patients referred to rheumatologists were judged at each visit for the presence or absence of axSpA, and the baseline judgement was reviewed after 2 years to assess its reliability. Baseline diagnostic judgments remained rather stable, and definite axSpA was present in one third of the patients referred to the rheumatologist (175 out of 555 patients; 32%). After 2 years, the number of patients with definite axSpA diagnosis changed to 165, due to 5% of the definite diagnoses being refuted and 8% gaining a definite axSpA diagnosis. Among the features related to axSpA, the presence (or absence) of imaging-detected sacroiliitis at baseline was the best discriminator for a definite diagnosis at 2 years.

In commenting on these findings, Alexandre Sepriano, MD, PhD, assistant professor of rheumatology, NOVA Medical School, Lisbon, Portugal, who was not involved in the study, said: "These data show that the key is likely the referral of the 'right patients' to tertiary care centers. The [ASAS] has developed referral criteria that can be used for this purpose. According to these, patients with chronic low back pain starting before 45 years of age should be referred to a rheumatologist if at least one additional SpA feature is present.

"It should be acknowledged that axSpA is not a disease of males only. In fact, there is a 1:1 ratio between males and females in the full spectrum of the disease. Also, although imaging findings are important, not all patients will have these. Similarly, not all patients with imaging abnormalities will have the disease, and their sole presence without other SpA features does not suffice for diagnosis."

Repeated Assessment: Is It Worth It?

Despite the positive findings described above, residual diagnostic uncertainty remained for 15% of patients, representing an obstacle to initiating an appropriate treatment. Therefore, it is important to understand whether and how the repeated assessment of axSpA features is of value for a definite diagnosis.

This last question was addressed in a second abstract also presented by Marques that focused on the yield of repeated assessment in CBP patients with suspected axSpA from the SPACE cohort. The main outcome of the study was the clinical diagnosis of definite axSpA at 2 years. Compared with baseline, at the 2-year evaluation 32 patients changed their diagnosis and were classified as definite axSpA: 16 were previously described as uncertain axSpA at baseline, 11 as uncertain no axSpA, and 5 as definite no axSpA.

On average, three axSpA features were present at baseline with one or two adjunctive features found throughout the study that led to the final diagnosis of definite axSpA. These adjunctive features were most commonly response to NSAIDs and sacroiliitis on MRI. Marques and colleagues concluded that the yield of repeated assessment in this setting was modest for a new diagnosis of definite axSpA. "Usefulness of repeating MRI in terms of diagnostic yield is low but can be considered in HLA-B27+ patients, especially if male," Marques said, commenting on the analysis of SpA features in patients who changed their diagnosis to definite axSpA at 2 years.

"The early diagnosis of axial spondyloarthritis remains a challenge," Sepriano said in commenting on the second SPACE study. "Probably one of the main reasons is the yet suboptimal awareness of the [full spectrum] of the disease in a primary care setting, in which most patients will first show up to get medical care. It is now well-known that patients do not always have changes in pelvic radiographs and that waiting for these to make a diagnosis of [radiographic] axSpA results in further delay and in missing many patients who will never develop these changes.

"Still, recognizing the clinical picture of early axSpA and differentiating it from other more common causes of chronic back pain (e.g., degenerative spinal disease) can sometimes be difficult. Continuous efforts in raising awareness and in education will likely result in further reducing the diagnostic delay gap and, as such, improve the prognosis of this often-debilitating rheumatic inflammatory disease."

One Epidemiologic Size Does Not Fit All

According to data from the International Map of Axial Spondyloarthritis (IMAS), axSpA clinical phenotype presentation shows great heterogeneity around the world. Marco Garrido-Cumbrera, PhD, of the University of Seville, Seville, Spain, presented the results of an analysis of an IMAS online survey (2017-2022).

The study, supported by Novartis, aimed at exploring differences in axSpA clinical phenotype presentation in a large sample of unselected patients: a total of 5557 individuals from 27 countries across five regions. The results showed statistically significant differences among countries in almost all the analyzed characteristics, from age at onset of symptoms (the highest in Latin America) to HLA-B27 positivity frequency (lowest in Latin America and highest in Asia).

Differences also emerged in the presence of a positive family history of the disease (most common in Europe) and of physical and mental comorbidities (common in Africa). The authors also reported treatment data showing that most of the patients had used NSAIDs, and almost half of the patients had ever taken biologic disease-modifying antirheumatic drugs. Data also showed a mean delay in diagnosis of 7 years, with the longest values observed in South Africa and the lowest in Asia.

A Consensus Definition of Early AxSpA

Dr Victoria Navarro-Compán

Early axSpA for the first time has been defined based on ASAS expert consensus, and the definition was presented by Victoria Navarro-Compán, MD, PhD, of La Paz University Hospital, Madrid, Spain, at the meeting. An international working group came to a definition based on the symptom duration and taking solely axial symptoms into account. At the end of a five-step process, the group successfully developed the first consensus definition of early axSpA: "patients with diagnosis of axSpA with axial symptoms duration of ≤2 years." Also to be noted are axial symptoms as assessed by a rheumatologist, which should include spinal/buttock pain or morning stiffness.

As reported by the authors, this ASAS definition is based on expert consensus, with the limitation of a lack of scientific evidence to support it, especially with regard to the specific duration of symptoms from the time of disease onset. Nonetheless, ASAS recommends the use of this definition in studies referring to early axSpA.

Marques reports no relevant financial relationships. Navarro-Compán reports serving on the speakers bureau for AbbVie, Eli Lilly, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, and UCB; consulting for AbbVie, Eli Lilly, Galapagos, MoonLake, Merck Sharp & Dohme, Novartis, Pfizer, and UCB; and receiving grant/research support from AbbVie and Novartis. Garrido-Cumbrera reports receiving grant or research support from Novartis.

European Alliance of Associations for Rheumatology (EULAR) 2023 Annual Meeting:
Abstract OP0005. Presented May 31, 2023
Abstract OP0054. Presented May 31, 2023
Abstract OP0055. Presented May 31, 2023
Abstract OP0187. Presented June 1, 2023

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