Long-term efficacy and safety of colchicine and anti-IL-1 blockers in FMF: results from the Eurofever multicenter observational study

Introduction: The majority of currently available data on familial Mediterranean fever (FMF) come from retrospective national or international studies. Methods: An observational study collected data on the Eurofever international FMF cohort. Patients fulfilling genetic and clinical Eurofever criteria were considered as FMF+. Patients not fulfilling clinical and/or genetic (one VUS or benign variants or negative for MEFV variants) criteria were considered as FMF-. Data on compliance to treatment and quality of life were also recorded. Results: Since November 2024, 876 FMF patients (466 M, 410 F) were enrolled, with a mean follow-up of 2.9 +/- 3.1 years. 730 (84 %) patients were classified as FMF+, 146 (16 %) as FMF-, with significant differences in the prevalence of clinical manifestations and treatment response between the two groups. At the last follow-up, 433 patients (50.6 %) still had some disease activity. At the last follow-up 749 (85.5 %) patients received colchicine with a relative under dosage of the drug. Anti-IL-1 treatment was reported in 133 patients (15.2 %), mostly canakinumab (117, 13.4 %). Treatment compliance was generally satisfactory, and adverse events were generally mild. Conclusions: Patients with an FMF-like phenotype who lack genetic confirmation display significant differences in clinical features and duration of attacks and show a less response to treatment during their disease course in respect, and thus, should be considered as FMF-mimics and investigated for other causes. Longitudinal data provides a more detailed comprehension of the long-term burden of FMF and the impact of treatment on disease activity and patients' quality of life.