AB0741 PREVALENCE AND ASSOCIATED FACTORS OF ATLANTO-AXIAL INSTABILITY IN PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS

Abstract

Background:Atlanto-axial instability (AAI) is a serious complication during Juvenile Idiopathic Arthritis (JIA). It can lead to severe neurological morbidity or mortality if left untreated (1).Objectives:To determine the prevalence of AAI in patients with JIA and to identify factors associated with an increased risk of its occurrence.Methods:A retrospective monocentric study was carried out on JIA patients (ILAR criteria). Data, including age at disease onset, JIA type, disease activity at AAI diagnosis and treatment were collected. Disease activity at JIA diagnosis was evaluated by JADAS10 (Juvenile Arthritis Disease Activity Score) in poly and oligoarticular subtypes and by BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) in arthritis related enthesitis form. Standard radiographs of the cervical spine were analyzed. The data were analyzed using the SPSS statistical package. A p value < 0.05 was considered significant.Results:We enrolled 48 JIA (31 male and 17 female) with a mean age at disease onset of 11.2 ± 3.8 years. The median disease duration was 84 months [2-408]. The median JIA diagnosis delay was 8 months [1-108]. The JIA subgroups were in decreasing order of frequency: Enthesitis-related Arthritis (n=32), Polyarticular RF- (n=4), Polyarticular RF+ (n=2), Oligoarticular (n=6), Systemic (n=2), Psoriatic Arthritis (n=1) and Undifferentiated (n=1).At diagnosis, median ESR and CRP were 44 mm/hour [2-100] and 24 mg/l [2-86] respectively. Median JADAS10 score was 4 [0-21]. Median BASDAI score was 6.2 [2-9.4].At follow-up, five patients (10.4%) had atlantoaxial subluxation and 17 had coxitis (43.8%).At bone densitometry, 45% of patients had osteroposis and 27.5% had osteopenia.An agreement was assessed between a long diagnosis delay and the following parameters: male gender (p=0.04) and osteoporosis (p=0.018). A Significant positive correlation was found between delay in JIA diagnosis and BASDAI score (p=0.047, r=0.63). No association was found between JIA diagnosis delay and JADAS score (p=0.56). Neither ESR (p=0.19) nor CRP (p=0.42) was associated with JIA diagnosis delay.Finally, no link was observed with the occurrence of hip arthritis (p=0.281) or atlantoaxial subluxation (p=0.137).Conclusion:In our study, the prevalence of AAI was 10.4%. Prolonged corticosteroid use and elevated inflammatory markers were the major factors associated with an increased risk of upper cervical spine involvement. Hence, targeted treatments are required to prevent cervical spine instability.