Ab0200 Redness Over a Joint as a Clinical Marker in Patients With Familial Mediterranean Fever

Background: Familial Mediterranean fever (FMF) is an autosomal recessive hereditary disease with a high prevalence in Middle Eastern and Mediterranean populations. Symptoms may include recurring episodes of fever of unknown origin, and abdominal, chest, or joint pain due to serosal inflammation. (Koehler, 2024). The most common musculoskeletal manifestation of FMF is acute recurrent monoarthritis (Mattiassich et al., 2013). Similar to FMF, other rheumatic diseases like rheumatoid arthritis (RA), ankylosing spondylitis (AS), Behcet disease (BD), inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE), gout, acute rheumatic fever (ARF) can also present with arthritis. Therefore, these diseases have been found in the differential diagnosis of FMF arthritis. One of the cardinal signs of inflammation is rubor (redness). It can manifest in arthritis, which is called red arthritis, and can be seen as a clinical manifestation in patients with FMF. Objectives: We aimed to determine whether red arthritis can be a distinctive manifestation in patients with FMF compared to other rheumatic diseases which can also have red arthritis occurrence. Methods: One hundred forty-nine FMF (Female:108, Male:41), 117 RA (Female:95, Male:22), 57 AS (Female:23, Male:34), 54 BD (Female:26, Male:28), 51 IBD (Female:27, Male:24), 50 SLE (Female:48, Male:2), 16 Gout (Female:5, Male:11), and one ARF (Female:1) patients were requested to complete a survey. The demographic data of the patients were obtained retrospectively. A photograph was utilized to investigate the presence of red arthritis and associated arthritis characteristics were also questioned. Results: In patients who demonstrated arthritis (Figure 1), red arthritis was the presenting sign in 79.8% (n:83) of patients with FMF, 20.5% (n:24) of patients with RA, 59.2% (n:16) of patients with BD, 57.7% (n:15) of patients with SLE, 75% (n:12) of patients with gout, 41.6% (n:10) of patients with AS, 100% (n:1) of patients with ARF, and 60% (n:3) of patients with IBD. Red arthritis was significantly more prevalent in FMF than in patients with other diagnoses (p-value:<0.001). The sensitivity and specificity rates of red arthritis to diagnose patients with FMF were 55.7% (95% CI: 47.35%-63.83%) and 76.6% (95% CI:71.77%-80.95%), respectively (Positive Predictive Value: 50.6%, 95% CI: 44.67%-56.53%; Negative Predictive Value: 70.3%, 95% CI: 76.87%-82.91%; Accuracy: 70.3%, 95% CI: 66.06%-74.3%). Among the FMF patients with red arthritis (n:83, Figure 2), fever (n:12,14.4%) was the most common accompanying symptom to swelling and redness over the joint, followed by abdominal pain (n:8, 9.6%), chest pain (n:9.6, 11%), back pain (n:6, 7.2%), skin rash (n:5, 6.0%), and erysipelas-like erythema (n:4, 4.8%). The median Visual Analogue Scale (VAS) score of the red arthritis attacks was eight. Attack duration is stated as about two days for 43 (51.8%) patients. The frequency of attacks for 29 (35%) patients is less than six times within a year. Conclusion: Redness over a joint, in other words, red arthritis, is a clinical finding that can be observed in many rheumatic diseases. When evaluating patients with red arthritis, physicians should consider the possibility of FMF as a potential diagnosis because of its considerable specificity and sensitivity rates, particularly in populations with a high prevalence of FMF. REFERENCES: [1] Koehler A. W. (2024). Unraveling the genome: Familial Mediterranean fever. Journal of the American Association of Nurse Practitioners, 36(1), 3–5. [2] Mattiassich, G., Semlitsch, G., Nadler, K., & Rainer, F. (2013). Familial Mediterranean fever without fever as a cause of monoarthritis. BMJ case reports, 2013, bcr2012008395. Acknowledgements: NIL. Disclosure of Interests: None declared.