Risk Factors for Spinal Structural Damage in a Chinese Cohort With Ankylosing Spondylitis

Sequence of Events in the Pathogenesis of Axial Spondyloarthritis: A Current Review-2023 SPARTAN Meeting Proceedings

PURPOSE OF REVIEW

Over the past two decades, significant progress has been made to untangle the etiology of inflammation and new bone formation (NBF) associated with axial spondyloarthritis (axSpA). However, exact mechanisms as to how the disease initiates and develops remain elusive.

RECENT FINDINGS

Type 3 immunity, centered around the IL-23/IL-17 axis, has been recognized as a key player in the pathogenesis of axSpA. Multiple hypotheses associated with HLA-B*27 have been proposed to account for disease onset and progression of axSpA, potentially by driving downstream T cell responses. However, HLA-B*27 alone is not sufficient to fully explain the development of axSpA. Genome-wide association studies (GWAS) identified several genes that are potentially relevant to disease pathogenesis leading to a better understanding of the immune activation seen in axSpA. Furthermore, gut microbiome studies suggest an altered microbiome in axSpA, and animal studies suggest a pathogenic role for immune cells migrating from the gut to the joint. Recent studies focusing on the pathogenesis of new bone formation (NBF) have highlighted the importance of endochondral ossification, mechanical stress, pre-existing inflammation, and activated anabolic signaling pathways during the development of NBF. Despite the complex etiology of axSpA, recent studies have shed light on pivotal pieces that could lead to a better understanding of the pathogenic events in axSpA.

Syndesmophyte Growth in Ankylosing Spondylitis: from Laboratory to Bedside

PURPOSE OF REVIEW

This study aims to review recent studies on risk factors for syndesmophyte growth in ankylosing spondylitis (AS) and on treatment effects.

RECENT FINDINGS

New genetic studies, including a genome-wide association study, provided only limited evidence of specific genetic associations with radiographic severity. Measures of inflammation, including vertebral osteitis and C-reactive protein level, were strongly associated with radiographic progression, while studies of adipokines had mixed results. Mesenchymal stem cells from HLA-B27 positive AS patients were found to promote vertebral ossification via a pathway of B27 misfolding, retinoic acid receptor-β activation, and increased bone alkaline phosphatase. Low vertebral trabecular bone density is associated with syndesmophyte growth, with reciprocal effects when bridged. Several observational studies suggested radiographic severity was reduced by treatment with tumor necrosis factor inhibitors, particularly when longer than 2 years. Syndesmophyte development in AS is the result of a complex, incompletely understood, interplay of inflammatory and mechanical factors.

Diagnostic delay in axial spondyloarthritis: a systematic review

Identification of axial spondyloarthritis (axSpA) remains challenging, frequently resulting in a diagnostic delay for patients. Current benchmarks of delay are usually reported as mean data, which are typically skewed and therefore may be overestimating delay. Our aim was to determine the extent of median delay patients’ experience in receiving a diagnosis of axSpA and examine whether specific factors are associated with the presence of such delay. We conducted a systematic review across five literature databases (from inception to November 2021), with studies reporting the average time period of diagnostic delay in patients with axSpA being included. Any additional information examining associations between specific factors and delay were also extracted. A narrative synthesis was used to report the median range of diagnostic delay experienced by patients with axSpA and summarise which factors have a role in the delay. From an initial 11,995 articles, 69 reported an average time period of diagnostic delay, with 25 of these providing a median delay from symptom onset to diagnosis. Across these studies, delay ranged from 0.67 to 8 years, with over three-quarters reporting a median of between 2 years and 6 years. A third of all studies reported median delay data ranging from just 2 to 2.3 years. Of seven variables reported with sufficient frequency to evaluate, only ‘gender’ and ‘family history of axSpA’ had sufficient concordant data to draw any conclusion on their role, neither influenced the extent of the delay. Despite improvements in recent decades, patients with axSpA frequently experience years of diagnostic delay and this remains an extensive worldwide problem. This is further compounded by a mixed picture of the disease, patient and healthcare-related factors influencing delay.

Key points • Despite improvements in recent decades, patients with axSpA frequently experience years of diagnostic delay. • Median diagnostic delay typically ranges from 2 to 6 years globally. • Neither ‘gender’ nor ‘family history of axSpA’ influenced the extent of diagnostic delay experienced. • Diagnostic delay based on mean, rather than median, data influences the interpretation of the delay time period and consistently reports a longer delay period.