THU0511 THE RISK FACTORS OF HIP OSTEOARTHRITIS IN JIA PATIENTS: THE DATA FROM A SINGLE CENTER RETROSPECTIVE CONTINUOUS STUDY

Background:Hip osteoarthritis (HOA) is a severe irreversible complication of patients with juvenile idiopathic arthritis (JIA) leads to intensive pain, disability and required total hip arthroplasty (THA) in childhood or in the young adults.Objectives:the aim of our study was to evaluate risk factors of HOA in JIA patients.Methods:we analyzed 753 patients with JIA for last 10 years. In each patient we observed if the HOA developed or no. We evaluated the main clinical JIA measurements, such a JIA category, CRP, ESR, WBC, PLT, active joints, initial or delayed hip involvement, ANA, HLA B27, onset age, JIA duration, time before HOA and before THA, bone metabolic markers, treatment, particularly glucocorticosteroids (GCS), their cumulative doses, route of administration (oral, intra-articular, pulse therapy). HOA was confirmed with radiological assessment (MRI and CT). For comparison analysis used nonparamentric statistics. Each possible variable was evaluated with univariate regression analysis and further multiple regression analysis was applied.Results:the comparative study between 2 groups shown in the table 1. HOA was detected in 48 (6.4%), in oligoarthritis-0%, in polyarthritis - 4.9%, in psoriatic arthritis - 5.0%, in enthesitis-related arthritis -11.8%, in systemic arthritis 19% (p=0.0000001), THA was performed in 16 (2.1%). Hip involvement at onset of JIA was similar in both groups (49.5% vs 41.7%, p=0.367).Table 1.Characteristics of JIA patients, depends on HOA development.ParameterHOA (n=48)No HOA (n=705)pOnset age, y8.0 (4.0; 12.5)5.9 (3.0; 10.7)0.045HLA B27, n (%)13/25 (52.0)88/283 (31.1)0.033JIA duration, y7.5 (3.2; 12.1)4.2 (1.8; 7.2)0.00007CRP, mg\l2.8 (0.8; 20.9)1.3 (0; 7.1)0.006Active joints, n11.0 (6.0; 27.0)6.0 (3.0; 12.0)0.000001Oral GCS, n(%)21 (43.8)131/704 (18.6)0.00003GCS pulse-therapy, n (%)21 (43.8)114/702 (16.2)0.000002GCS, cumulative doses, mg5000 (3000; 16000)2000 (1000; 4000)0.001Biologics, n (%)43 (89.6)308 (43.7)0.0000001Remission, n (%)24 (50.0)461 (65.4)0.03Time, before remission, y7.4 (3.9; 12.3)3.0 (1.4; 6.2)0.0000001Alkaline phosphatase, U\l129.3 (84; 244)223 (147; 386)0.00001Delayed hip involvement, n (%)28 (58.3)24/87 (27.6)0.00004We calculated cut-off and OR of variables, associated with HOA development (table 2). After selection of 26 clinically meaningful and statistical significant risk factors only 22 pass the univariate regression analysis. In multiple regression analysis the main independent risk factors of HOA development were: HLA b27 (p=0.001), oral GCS/pulse therapy GCS (p=0.03) and alkaline phosphatase≤165 U/l (p=0.00006).Table 2.Cutt-offs, odds ratio for HOA risk factors in JIA patients.ParameterSeSpOR (95%CI)pActive joints > 489,642,06,2 (2,4-15,9)0,000002Alkaline phosphatase ≤ 165 U/l65,970,84,7 (2,4-9,2)0,000001GCS > 2700 mg82,658,16,6 (2,1-20,6)0,0004Time before remission>5 years66,778,97,5 (3,1-18,0)0,0000001Time before biologics >7,8 years44,286,75,2 (2,6-10,2)0,0000001Conclusion:the main risk factors of HOA were increased inflammatory activity, systemic arthritis, HLA B27, systemic corticosteroids, delayed remission and biologics, decreased bone metabolism. Delayed hip involvement underline the possible non-inflammatory mechanism of HOA, such as avascular necrosis.Disclosure of Interests:None declared