POS1339 MORE FREQUENT AND EARLIER HIP INVOLVEMENT IN SPONDYLOARTHRITIS ASSOCIATED WITH FAMILIAL MEDITERRANEAN FEVER
Authors: M. Bektaş, S. Sari, C. Cetin, B. Ç. Yalçin Dulundu, N. Koca, B. Ince, Y. Yalçinkaya, B. Artim-Esen, M. Inanc, M. L. Ocal, A. Gül
Journal: Annals of the Rheumatic Diseases (2021)

Background: Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by the MEFV gene variants. Although association between FMF and spondyloarthritis (SpA) has previously been reported, clinical and laboratory features of patients with FMF and SpA have not been defined in detail. Objectives: We aimed to evaluate clinical and laboratory characteristics, disease outcome and biologic responses of patients with FMF+SpA compared to patients with only SpA who were followed-up in our tertiary referral center. Methods: Database of FMF Clinic was screened for FMF patients with coexistent SpA and 113 patients were identified fulfilling Tel Hashomer and ASAS criteria for FMF and SpA, respectively. A group of patients with SpA without FMF matched for age, gender and disease duration were selected as the control group. Results: Thirteen patients were excluded because of missing data, and 100 patients (F/M: 52/48) were included into the analysis. Mean follow-up time was 93.6 ± 77 (range[r]: 3-324) months and mean patient age was 43.3 ± 12 (r: 20-87) years. Mean age of onset for FMF was 12.5 ± 8 (r: 1-36) and for SpA was 25 ± 11 (r: 7-72) years. SpA findings was classified as axial in 35.4%, axial and peripheral in 47.9% and only peripheral in 16.7% in FMF+SpA group. Half (49%) of the patients had hip involvement (70% bilaterally), and 21.5% of them needed total hip joint replacement (TJR), which were significantly more frequent compared to control group. Two exon 10 MEFV variants were found in 69.4%, and most (69.8%) had homozygous M694V. Hip involvement was more frequent in patients with two exon 10 variants (p=0.036; OR=4.4) compared to those with one variant; and TJR was more frequent in those with homozygous M694V compared to other exon 10 variants (p=0.001; OR=10). Radiographic sacroiliitis was less frequent in patients with homozygous M694V (p=0.019; OR=5.48). HLA-B27 positivity was not associated with hip or axial involvement in patients with FMF+SpA. Biologics were used in 60 patients (anti-TNF in 43, secukinumab in 1, and tocilizumab in 2). Anti-IL-1 drugs were used in 23 patients for refractory FMF. In 9 patients, anti-TNF and anti-IL-1 drugs were tried for refractory joint involvement: 5 switched to anti-TNFs from anti-IL-1, 4 patients switched to anti-IL-1 from anti-TNFs. Biologic DMARD requirement was more frequent in patients with two exon 10 variants (p=0.006; OR=7.4), especially in those with homozygous M694V (p=0.006; OR=7.6). Although anti-IL-1 usage did not differ among MEFV variants, anti-TNF was used more frequently in patients with homozygous M694V (p=0.007; OR=7.2). FMF+SpA patients had higher serum CRP and developed amyloidosis more frequently than those patients with SpA. Table 1. Comparison of clinical and laboratory findings between the patients with FMF+SpA and SpA control FMF + SpA (n=100) SpA (n=217) P value Age (years)* 43.3 ± 12 43.4 ± 11 0.6 Sex (n, %) Male 48 104 (47.9) 0.99 Female 52 113 (52.1) Duration of SpA (monnths)* 181.6 ± 108 180.2 ± 112 0.8 Age onset of SpA (years)* 25.1±11 28.4±8 0.008 Peripheral arthritis (n, %) 35/80 (43.8) 79/212 (37.3) 0.3 HLA-B27 positivity (n, %) 6/21 (28.6) 105/139 (75.5) &lt;0.001 (OR=18.9) CRP (mg/dL)* 26.7 ± 25** 18.96±29 0.001 ESR (mm/hour)* 39.7 ± 27 39.4 ± 28 0.8 Hip involvement (n, %) 47/96 (49) 23/118 (19.5) &lt;0.001 (OR=20.9) TJR (n, %) 20/93 (21.5) 8/205 (3.9) &lt;0.001 (OR=23.3) Fulfilling mNY criteria (n, %) 52/81 (64.2) 164/199 (82.4) 0.001 (OR=10.8) Biologic DMARD (n, %) 60 68/214 (31.8) &lt;0.001 (OR=22.5) Anti-TNF (n, %) 46 68/214 (31.8) 0.015 (OR=5.96) Amyloidosis (n, %) 16 5/205 (2.4) &lt;0.001 (OR=19.3) * mean±standard deviation, **during the attack-free period Conclusion: In this group of FMF+SpA patients, hip involvement and need for TJR were more frequent and associated with penetrant MEFV variants rather than HLA-B27 positivity. These patients had higher inflammatory response and risk of developing amyloidosis, and they needed biologics more frequently compared to SpA group. More severe disease course in FMF+SpA patients requires further attention and analysis in larger cohorts. Disclosure of Interests: None declared