Axial spondyloarthritis (axSpA) is a chronic inflammatory disease including both radiographic (historically known as ankylosing spondylitis) and non-radiographic forms. It leads to chronic pain, structural damage following persistent inflammation, and disability [1]. The disease often begins in the second or third decade of life, impacting patients during their most active years professionally, socially, and within their families, and adversely affecting psychological health. Early diagnosis is crucial to prevent the negative consequences associated with disease progression and higher burden of the disease. Advancements such as magnetic resonance imaging (MRI) of the sacroiliac joints (SIJ) have improved early detection by identifying inflammation before irreversible structural damage occurs [2,3]. Despite these developments, early diagnosis remains a significant unmet need in axSpA management.

Recent studies, including a meta-analysis and the International Map of Axial Spondyloarthritis (IMAS) survey, report an average diagnostic delay of approximately seven years [4,5]. Factors contributing to longer delays include female gender, younger age at symptom onset, country of residence, lower education levels and absence of extra-musculoskeletal manifestations (EMM) and greater number of health care professionals (HCPs) seen before diagnosis [4,6]. The results from the IMAS showed that patients with axSpA visited on average two different healthcare professionals before being referred to a rheumatologist, including general practitioners, orthopedic specialists, physiotherapists and osteopaths [4,5].

Multiple referral strategies have been developed for primary care physicians and other specialists, but their implementation faces challenges [7]. Primary care physicians are often overloaded and may lack awareness of referral procedures for axSpA. Rheumatologists usually do not have dedicated time to educate other HCPs, and many strategies require tests such as C-reactive protein (CRP), HLA-B27, or MRI, which may not be readily available in primary care settings [7,8]. While patients suspected of having axSpA should ideally be referred to a rheumatologist within three working days and assessed within three weeks according to the Assessment of SpondyloArthritis international Society (ASAS) Quality Standards, this goal is not usually met in most settings[9]. Programs like the ESPeranza Program in Spain demonstrated that educating HCPs and facilitating referrals can improve early diagnosis [10]. However, after some years, and due to the challenges of encountering sustained support, such initiative did not have lasting impact.

In clinical practice, chronic back pain (CBP) is the most common musculoskeletal complaint, but only about 5 % of cases are attributable to axSpA [11,12]. Many patients with CBP are initially assessed by specialists other than rheumatologists, contributing to axSpA diagnostic delay. Identifying which patients are likely to have axSpA is a significant challenge, yet crucial to reducing this delay and preventing the negative outcomes of late diagnosis. To address this, we conducted a study to determine the prevalence and features associated with axSpA diagnosis in young adults with CBP referred to specialists other than rheumatologists. Additionally, we aimed to evaluate the presence of inflammatory and structural lesions on spinal and SIJ MRI in this population.