POS1364 MUSCULOSKELETAL VARIANT OF FAMILIAL MEDITERRANEAN FEVER MAY HAVE MORE SEVERE DISEASE
Authors: M. E. Tezcan, R. Mercan, Ö. Volkan, N. Şen, S. Yilmaz-Oner
Journal: Annals of the Rheumatic Diseases (2021)

Background: Familial Mediterranean fever (FMF) is one of the prototypes of auto inflammatory diseases. Besides recurrent serositis, some patients also have musculoskeletal involvement similar to spondyloarthropathies (SpA) (1). These patients usually have more severe disease (2). In addition, some experts think FMF can be considered a variant of SpA. Objectives: There is handful of studies in literature that evaluated the disease severity, FMF complications and treatment variations in FMF patients with individual musculoskeletal features separately (3). However, these patients can be considered as musculoskeletal/SpA variants of FMF. Here, we evaluated the validity of hypothesis: “The patients with any of musculoskeletal symptoms or SpA variant of FMF have more severe disease.” Methods: We included 218 FMF patients who met Modified Tel- Hashomer criteria. We divided the patients according to suffering from any of the musculoskeletal symptoms (arthritis, enthesitis, arthralgia/myalgia, sacroiliitis,standing myalgia).Here, arthritis, enthesitis were diagnosed with physical examination according to appropriate methods. Standing myalgia diagnosis was depending upon patients’ history. Lastly, sacroiliitis was demonstrated in radiological screening. The patients with any of the musculoskeletal symptoms were considered musculoskeletal variants of FMF. In this study we compare disease characteristics and treatment differences between the groups. We used Mann-Whitney-U or chi-square tests where appropriate. Results: There were 126 (57.7%) patients in the musculoskeletal group. FMF patients in both groups had similar demographic and disease characteristics except musculoskeletal signs. Musculoskeletal variant group had higher The International Severity Score for FMF (ISSF) (p&lt;0.001); more frequent (p=0.009), intense (p=0.009) and longer attacks (p=0.001) than the others. Also, patients with musculoskeletal variant received higher colchicine dose (p=0.006). Table 1. Demographic, disease and treatment characteristics of the patients Musculoskeletal variant n=126 Non-musculoskeletal group n=92 p Gender (M/F) 45/81 34/58 0.85 Disease duration(year) 9.6±7.3 8.3±6.9 0.08 Fever (%) 81 (64.3) 53 (57.6) 0.37 Abdominal pain (%) 106 (84.1) 83 (90.2) 0.19 Plevritis (%) 46 (36.5) 28 (30.4) 0.35 Number of attack region 1.7±0.8 1.3±0.5 &lt;0.001 Attack frequency (/year) 3.4±5.0 2.1±3.5 0.009 Attack duration (day) 1.6±1.7 0.9±1.5 0,001 Attack VAS score (0-100) 33.3±32.7 23.1±31.5 0,009 ISSF score 1.6±1.3 0.6±0.9 &lt;0.001 Exon 10 homozygote (%) 33 (26.2) 19 (20.7) 0.42 Amyloidosis (%) 6 (4.8) 2 (2.2) 0.47 Colchicine dose (mg/day) 1.4±04 1.2±0.4 0.006 Il-1 blocker (%) 1 (0.8) 2 (2.2) 0.57 M: Male; F: Female; ISSF: The International Severity Score for FMF; VAS: Visual analog score. All continuous variables shown as mean±SD. p&lt;0.05 is significant. Conclusion: We showed that FMF patients with musculoskeletal signs have more severe disease and received higher colchicine dose as compared to non-musculoskeletal group and can be considered as the SpA variant of FMF or a distinct variant of SpA. References: [1]Atas N, Armagan B, Bodakci E, et al. Familial Mediterranean fever is associated with a wide spectrum of inflammatory disorders: results from a large cohort study. Rheumatol Int 2020; 40:41-48. [2]Sen N, Yilmaz M, Mercan R, et al. Enthesitis may be one of the signs of severe disease in familial Mediterranean fever. Clin Rheumatol 2020 [3]Eshed I, Rosman Y, Livneh A, et al. Exertional leg pain in familial Mediterranean fever: a manifestation of an underlying enthesopathy and a marker of more severe disease. Arthritis Rheumatol 2014; 66:3221-6. Disclosure of Interests: None declared