Pos0179 Initial Infection, Hla B27 and Reactive Arthritis: Retrospective Study of 39 Cases Followed in a Military Rheumatology Department

Background: Reactive arthritis (ReA) is part of the large group of spondyloarthritis. The typical clinical picture refers to the "oculo-urethro-synovial" triad who follows an infection, often digestive or urogenital [1]. Soldiers, like travelers, are exposed to fecal diseases [2,3]. Objectives: The objective of our study was to analyze clinical and biological characteristics of patients with reactive arthritis, and the influence of the type of initial infection and the HLA B27 on the parameters studied. Methods: This is a retrospective study of 39 patients with a diagnostic of reactive arthritis. These patients were hospitalized in the military rheumatology department of Begin Hospital (Saint-Mandé, France) from January 2000 to December 2021. Results: Our cohort included 39 patients with 27 military patients, composed 94% of men, with an average age of 31.5 years. The mean time to have joint symptoms was 16.4 days. The initial CRP level was around 104.3 mg/L with an inflammatory joint fluid formula composed of 15,569 elements/mm3. Oligoarticular involvement was the most common with a mean of 1.6 joints affected. The knee was the most affected joint regardless of the number of joints affected. The most common extra-articular involvement was conjunctivitis, found in 14 patients. From the 39 patients included, 15 evolved to a chronic form. 64.1% of patients were HLA B27 positive. In 59% cases, there was a notion of previous travel, consistent with the contracting of the initial infection, represented mainly by military patients. For 23 patients, the initial symptoms were digestive and for 15 of them urogenital. For 1 patient the type of initial infection was not found. The bacteria mainly represented was Chlamydia Trachomatis, found in 9 patients. 4 digestive germs have been identified: Salmonella, Shigella, Campylobacter and Entamoeba Histolytica. Digestive infections were significantly more frequent in the military patients (p=0.033). The CRP level was significantly higher in reactive arthritis occurring after a digestive infection (p = 0.004). The type of initial infection had no influence on the number of swollen joints, on the various extra-articular lesions or on the chronicization of ReA. The 25 HLA B27 positive patients also had significantly higher CRP (p = 0.029). On the extra-articular level, conjunctivitis was significantly more frequent with HLA B27 (p = 0.006), with no difference regarding other extra-articular signs. Conclusion: This study provides a new overview of reactive arthritis cases in a french rheumatology department. Even if the sample size is small, the number of patients included is one of the largest collected in recent studies. Our results confirm pre-existing data [4, 5], but also show us new highlights. Indeed, we find there was more biological inflammation in reactive arthritis who has followed a digestive infection. We can imagine that some of them can be avoided with better prevention of intestinal diseases. However, because of the size of the sample and the monocentric nature, additional studies remain necessary. REFERENCES: [1] Amor B. Reiter's syndrome. Diagnosis and clinical features. Rheum Dis Clin North Am. nov 1998;24(4):677-95, vii. [2] Porter CK, Olson S, Hall A, Riddle MS. Travelers' Diarrhea: An Update on the Incidence, Etiology, and Risk in Military Deployments and Similar Travel Populations. Mil Med. sept 2017;182(S2):4-10. [3] Riddle MS, Sanders JW, Putnam SD, Tribble DR. Incidence, etiology, and impact of diarrhea among long-term travelers (US military and similar populations): a systematic review. Am J Trop Med Hyg. [4] Courcoul A, Brinster A, Decullier E, et al. A bicentre retrospective study of features and outcomes of patients with reactive arthritis. Joint Bone Spine. 2018;85:201–5 T5 [5] Brinster A, Guillot X, Prati C, Wendling D. Evolution over thirty years of the profile of inpatients with reactive arthritis in a tertiary rheumatology unit. Reumatol Clin. 1 janv 2018;14(1):36-9. Acknowledgements: NIL. Disclosure of Interests: None declared.