Characteristics of arthritis in patients with familial Mediterranean fever

Background Many of the familial Mediterranean fever (FMF) patients present with arthritis during attacks, which may vary in its characteristics. Aims In this study, we aimed to describe and characterise arthritis in FMF patients. Methods We used our hospital's record system to retrospectively identify FMF patients with arthritis who presented to our clinic between 2005 and 2020. The prevalence, laboratory results of attack, remission periods, genetic mutations, demographic data, characteristics of attacks, characteristics of arthritis, comorbidities, treatments and treatment responses were recorded. Results Nine hundred fifty‐four patients from a cohort of 2350 FMF patients had arthritis (40%). The male/female ratio was 0.49 in patients with arthritis. The frequency of at least one exon 10 mutation was high. The age of onset of symptoms was earlier for patients with arthritis. Monoarticular pattern was more frequent compared to oligo‐ and polyarticular patterns. Colchicine resistance was higher; the required colchicine dose for disease control and the frequency of use of biological agents were higher compared to general FMF population. Conclusion Since M694V mutation is common and the colchicine dose required for disease control is high, we can conclude that the disease activity is high in FMF patients with arthritis. The frequency of sacroiliitis and spondyloarthropathy is significantly increased, especially in individuals with M694V mutation, suggesting that there may be a common pathway in their pathogenesis. FMF should be included in the differential diagnosis in patients presenting with arthritis in FMF endemic regions.