SAT0308 CLUSTER-BASED SPONDYLOARTHRITIS PHENOTYPES DEFINED AT BASELINE ARE PREDICTIVE OF 5-YEAR SEVERITY OUTCOME IN THE DESIR COHORT

Background The course of axial spondyloarthritis (SpA) is heterogeneous, varying from mild to severe and remains to be better defined. DESIR is a French cohort of early undifferentiated axial SpA that are longitudinally followed-up, offering such opportunity. We recently performed a cluster analysis in the DESIR cohort, according to baseline characteristics and identified 2 clusters: one characterized by an isolated axial disorder (A for axial) and one by additional high frequency of peripheral manifestations (B for both)1. Those cluster-based SpA phenotypes could correspond to different levels of disease severity. Objectives To assess whether cluster-based SpA phenotypes defined at baseline are conserved over time and might predict disease outcome at follow-up. Methods We analysed longitudinal data from the 586 patients who completed all follow-up visits until 5-year (mo 6, 12, 18, 24, 36, 48 and 60) out of the 679 patients included in the DESIR cohort used to define clusters at baseline. We performed a linear mixed-effect analysis for quantitative variables (using lme4 R package) and a generalized linear mixed-effect analysis for qualitative variables (using glmer R package) with cluster and follow-up visits as fixed effects and subjects as random effect. P-values were obtained by likelihood ratio tests of the full model with cluster against the model without cluster as fixed effects. Results Over the time, both clusters continued to show sustainable consistent differences characterized by higher frequency of peripheral involvement, higher disease activity, worse patient-reported outcome, higher frequency of conventional DMARDs and TNF blockers usage in cluster B, and higher frequency of radiographic and MRI sacroiliitis at 2 and 5 years in cluster A (Table). Conclusion Cluster-based SpA phenotypes defined at baseline in the DESIR cohort were predictive of severity outcome after 5 years. Patients from cluster A were more prone to develop sacroiliitis despite lower disease activity over the time, whereas those from cluster B had poorer clinical outcome and higher need for conventional DMARDs and TNF blockers. Reference [1] Costantino F, Aegerter P, Dougados M, Breban M, D’Agostino M-A. Two Phenotypes Are Identified by Cluster Analysis in Early Inflammatory Back Pain Suggestive of Spondyloarthritis: Results From the DESIR Cohort. Arthritis & Rheumatology (Hoboken, NJ). 2016;68(7):1660–8. Disclosure of Interests Felicie Costantino: None declared, Philippe Aegerter: None declared, Anna Molto: None declared, Maxime Breban Grant/research support from: Pfizer, UCB, Novartis, MSD, Consultant for: UCB, Maria-Antonietta d’Agostino: None declared