POS1297 SACROILIITIS AT DIAGNOSIS ASSOCIATED WITH LESS DISEASE FLARE AFTER STOPPING MEDICATION - OUTCOMES AND PREDICTORS OF A SOUTHEAST ASIAN ENTHESITIS RELATED ARTHRITIS (ERA) LONGITUDINAL COHORT

Abstract

BackgroundERA is a subtype of Juvenile Idiopathic Arthritis (JIA) characterized by involvement of entheses and axial skeleton. Outcomes have been shown to be poorer compared with oligoarticular and polyarticular JIA1.ObjectivesTo assess short-and long-term outcomes and predictors of ERA in a large monocentric cohort in Singapore.MethodsChildren diagnosed with ERA according to ILAR criteria from 2002 to 2021 at KK Women’s and Children’s Hospital, Singapore, were recruited. Outcome statuses were defined according to the criteria for clinical inactive disease (CID) and complete remission (CR) proposed by Wallace et al.2, with additional criteria of no enthesitis and no active sacroiliitis on MRI. Nonparametric descriptive statistics were used. Univariate and multivariate analysis were performed using logistic regression analyses. The significant level was set at < 0.05.ResultsA cohort of 151 ERA patients (male 86%; Chinese 81%) were included. Median age at onset was 11.9 years (IQR 9.4-13.9) and disease duration was 5.3 years (IQR 2.9-8.4). HLA-B27 was positive in 83% of the patients. At diagnosis, 39% of the patients had sacroiliitis, 46% had hip arthritis, 36% had knee arthritis and 25% had enthesitis. Methotrexate was used in 77% of the patients, while biologics was started in 72% of the patients.CID was achieved in 92% of the patients, of which 27% achieved CID in 6 months or less. Sacroiliitis at diagnosis is an unfavourable predictor of CID at 6 months but not a significant predictor of ever achieving CID. Older age at diagnosis is also an unfavourable predictor of CID ever.Medication was totally discontinued in one third of the patients. Half of them went on to have complete remission (CR) off medication. Favourable predictor includes male gender, while positive HLA-B27 and ANA were unfavourable predictors.Two thirds of the patients with CID had at least one disease flare (23% flared after off medication, 13% flared after CR). Both intra-articular joint injection and anti-TNF use were associated with flare after CID, while anti-TNF use was associated with flare after off medication. Sacroiliitis at diagnosis is a protective predictor of flare after stopping medication.ConclusionDespite a high proportion of ERA patients achieving CID, only one third could stop medication completely with high rates of disease flare even after attaining CR. Unfavourable predictors include older age at onset as well as HLA-B27 and ANA positivity. While sacroiliitis at diagnosis is a negative predictor of CID at 6 months, it is protective predictor of flare after discontinuing medication.