22 Defining the cystic fibrosis arthropathy phenotype: A serological and imaging pilot study

Objective Cystic Fibrosis Arthropathy (CFA) is a term commonly used for joint pain +/– swelling seen in some patients. Early studies into CFA focused on presence of rheumatoid factor and immunological changes on synovial biopsy, with parallels drawn between respiratory and joint activity. Identification of anticyclic citrullinated peptide antibodies (anti-CCP) as a marker of rheumatoid arthritis (RA), along with increased access to sensitive imaging techniques including ultrasound (US) and magnetic resonance imaging (MRI), offer great potential to more accurately understand the type(s) of inflammatory arthritis that may underlie CFA. The aim of this pilot study was to phenotype an active CFA cohort using serology and imaging, as a basis for further work in this understudied area. Methods This was a prospective observational cohort study of symptomatic CFA patients presenting with joint pain +/– joint swelling. Participants underwent serological testing, clinical and US joint and entheseal assessment, and MRI of the most symptomatic joint. Results Ten symptomatic patients were studied with 9/10 having positive clinical findings. Five patients had positive findings on MRI (3 of whom had received IV gadolinium contrast). This included patients with significant erosive changes. Inflammatory changes on US were seen in 8/10 cases. One patient was CCP positive suggestive of RA, and two were anti-nuclear antibody positive. Conclusion In CFA, imaging, and to a lesser extent serology, identified inflammatory joint pathology in a proportion of cases, providing important pilot data to explore in a large CFA cohort examining the clinical and imaging phenotype of this group.