Arthritis in Cystic Fibrosis-Comparison of a Single-Center Cohort and Published Case Reports/Series and a Review of the Literature.

Cystic fibrosis (CF) is commonly associated with musculoskeletal issues including inflammatory arthritis, CF arthritis. We present a retrospective cohort study which aims to describe the clinical characteristics, prevalence, and demographic associations of CF arthritis using both a clinical and literature cohort. We identified adult CF patients (≥ 18 years) with arthritis from the rheumatology clinic at Rigshospitalet (2020-2022). The clinical cohort (CC) was reviewed through electronic medical records. Literature cases were identified by searching online databases for relevant studies, case reports, and reviews on CF arthritis. Eleven CF patients with arthritis were identified (CC) from our clinic and 54 cases from the literature (literature cohort, LC). Both cohorts showed equal gender distribution. In the LC, arthritis onset had a median age of 11 years (range 2-28), while in the CC it was 26 years (range 13-43). Clinical features were similar in both cohorts: the majority had episodic relapsing arthritis, with two-thirds having mono-/oligoarthritis and one-third polyarthritis. Large joints were most commonly affected. No clear link to pulmonary disease or serologic markers was found. Immunosuppressive treatment was safe. CF arthritis is a heterogeneous condition, presenting as non-erosive, episodic oligo- or polyarthritis affecting both large and small joints.