POS1297 HOW HLA B27 PREVALENCE IN THE POPULATION INFLUENCE ON FEATURES OF JUVENILE IDIOPATHIC ARTHRITIS: DATA FROM SAKHA REPUBLIC (YAKUTIA)
Authors: F. Vinokurova, L. Sorokina, V. Argunova, P. Sleptsova, T. Bourtseva, V. Chasnyk, M. Kostik
Journal: Annals of the Rheumatic Diseases (2021)

Background: Sakha Republic (Yakutia) - SR(Y) is a bid arctic region of Russia with high proportion of aboriginals - Yakutians (50%), intra-national marriages, increased level of inbreeding and high distribution of HLAB27 among aboriginals – 33%, according the epidemiological studies. The main type of arthritis is ankylosing spondylitis in adults and enthesytis-related arthritis (ERA) of juvenile idiopathic arthritis (JIA) in children. The pattern of arthritis distribution in adults and children in SR(Y) is differ from Caucasians and similar to Native Americans. Objectives: Our study aimed to evaluate the features of JIA in aboriginals of SR(Y), associated with high prevalence of HLAB27 antigen. Methods: In the retrospective study we included 144 Yakutians who were admitted in the rheumatology department of Yakutsk in 2007-2016 years and 753 JIA patients Caucasian origin in Saint-Petersburg in the same years. We evaluated routine clinical and laboratorial features. HLA B27 was evaluated according the clinical judgement of the attending physicians. Results: ERA is a main JIA category in Yakutians. The main features the male predominance, higher onset age, high inflammatory activity, lower number of active joints, high incidence of hip and sacroiliac joints involvement, lower levels of psoriasis and uveitis. Yakutians have rare the involvement of cervical spine (6% vs 14%, p=0.0000001), TMJ (1% vs 6%, p=0.027), elbow (8% vs 16%, p=0.012), wrist (18% vs 28%, p=0.017), MCP (7% vs 21%, p=0.00005), PIP (8% vs 25%, p=0.00005). The treatment rates of methotrexate and biologics were similar between groups, but in Yakutians the biologics were administered earlier, because methotrexate failed and often was ineffective. The cumulative probability to receive biologics was higher in Yakutians compare to Caucasians: HR=3.4 [2.6; 4.4], p=0.000001 (Figure 1). The main biologic in Yakutians was etanercept (49/70; 70%). Yakutians received corticosteroids and cyclosporine A rarely, due to low incidence of systemic onset JIA and oligoarthritis with uveitis. It was observed, that the HLA B27 as a risk factors had different significance in Yakutians and Caucasians. HLA B27 presence increased the risk of ERA OR=2.72 (1.3; 5.6) p=0.01 in Yakutians and OR=69.2 (29.5; 162.3), p=0.00001 for Caucasians; for biologic administration: 0,86 (0,4; 1,8), p=0.529 and 2,45 (1,5; 4,0), p=0.0003, respectively. Figure 1. Cumulative probability to leave without biologics between Yakutian and Caucasian JIA patients. Conclusion: High distribution of HLA B27 antigene in Yakutians, lead to different pattern of JIA categories distributions and patient’s management. This work was supported by the Project of the Ministry of Science and Higher Education of the Russian Federation (basic part of funding to M.K. Ammosov North-Eastern Federal University #FSRG-2020-0016) and by the RFBR grant #18-05-600035_Arctika. Table 1. Differences between Yakutian and Caucasian JIA patients. JIA features Yakutians, n=144 (% ) Caucasians, n=723 (% ) р Gender, boys, n (%) 85 (59.0) 279 (38.6) 0.000006 Onset age, years 10.6 (6.0; 13.4) 6.0 (3.0; 10.3) 0.0000001 JIA categories, n (%) Oligoarthritis 36 (25.0) 188 (26.0) 0.0000001 Poly, RF (-) 21 (14.6) 248 (34.3) Poly, RF (+) 1 (0.7) 22 (3.0) Systemic onset 4 (2.8) 53 (7.3) ERA 76 (52.8) 171 (23.7) Psoriatic arthritis 6 (4.2) 41 (5.7) Active joints 4.0 (3.0; 6.0) 6.0 (3.0; 12.0) 0.0000001 Uveitis, n (%) 16 (11.1) 114/503 (22.7) 0.002 Psoriasis, n(%) 3/143 (2.1) 46/719 (6.4) 0.043 Hip involvement 50 (34.7) 146 (20.2) 0.0001 Sacroiliitis 46 (31.9) 69 (9.6) 0.0000001 HLA B27, n (%) 76/131 (58.0) 105/301 (34.8) 0.00001 ANA, n (%) 4/46 (8.7) 204/444 (46.0) 0.00001 RF, n (%) 3/141 (2.1) 22/403 (5.5) 0.104 Biologics, primary, n (%) 70/144 (48.6) 347 (48.0) 0.892 Time before first biologics, years 0.6 (0.3; 1.4) 2.6 (1.0; 5.4) 0.0000001 Disclosure of Interests: None declared