POS0941 IN SPONDYLOARTHRITIS PATIENTS THE PRESENCE OF COMORBIDITIES IS AN INDEPENDENT PREDICTOR OF INSUFFICIENT RESPONSE TO THERAPY WITH BIOLOGIC AGENTS AND TREATMENT DISCONTINUATION
Authors: I. Flouri, N. Kougkas, N. Avgustidis, A. Repa, A. Eskitzis, A. Molla Ismail Sali, S. Pitsigavdaki, K. Pateromichelaki, E. Kalogiannaki, G. Bertsias, P. Sidiropoulos
Journal: Annals of the Rheumatic Diseases (2021)

Background: Long-term observational studies of patients under biologic disease-modifying anti-rheumatic drug (bDMARD) therapies in routine clinical practice can provide us with important data regarding patients with comorbidities, who are usually excluded from randomized controlled studies. Objectives: To study the impact of comorbidities in the outcome (response and persistence to therapy) of patients with spondyloarthritis (SpA) receiving bDMARDs in real-world clinical practice. Methods: Prospective study of all patients who start a bDMARD in a tertiary centre University Hospital after their consent. All patient comorbidities [among a list of approximately 100 pre-specified major comorbidities] are registered by treating physicians at baseline and during follow-up. Comorbidities were studied as total Comorbidities Count (CC) and rheumatic disease comorbidity index (RDCI). Statistical analyses were performed using logistic and Cox regression models, adjusting for the potential confounding of age, sex, disease duration, diagnosis (axial vs. peripheral SpA), number of previous conventional synthetic and biologic DMARDs, year of therapy start, and co-administered methotrexate and corticosteroids (yes/no). Analyses of response to therapy also included baseline BASDAI or ASDAS indices as confounding variables. Results: A total of 603 biologic treatments (1 st : 298, 2 nd : 157, ≥3 rd : 148) were analyzed. Half (51%) of the patients were female, 413 patients had axial SpA (AxSpA) and 190 peripheral SpA (perSpA). At baseline, median (IQR) age: 48 (38-57) years, disease duration: 11 (4-19) years, CC: 2 (1-4) and RDCI: 1 (0-2). Both comorbidity indices were significantly higher in perSpA compared to AxSpA (p&lt;0.001). At 6 months of therapy, 31% of patients with AxSpA achieved BASDAI50 and 39% had ASDAS-ESR &lt; 2.1. Higher CC was an independent predictor of insufficient response according to BASDAI50 [OR (95%) = 0.70 (0.52-0.94), p=0.019] and higher RDCI was predicting failure to achieve ASDAS-ESR &lt; 2.1 [OR (95%) = 0.59 (0.37-0.94), p=0.027]. Other independent predictors of non-response were age, longer disease duration and (for ASDAS-ESR&lt;2.1) higher baseline disease activity. During 1405 patient-years of follow-up, 349 (58%) treatments were discontinued. The adjusted hazard ratio for bDMARD discontinuation within the first 2 years of treatment due to insufficient response was doubled in patients with CC ≥2 versus those with CC ≤1 [HR = 2.27 (1.14-4.53), p=0.020] or with RDCI ≥1 (vs. RDCI = 0) [HR = 2.23 (1.22-4.07), p=0.009]. Comorbidities’ indices were not significant predictors of treatment discontinuations due to adverse events. Conclusion: The presence of comorbidities in patients with SpA is an independent predictor for insufficient 6-month response to bDMARDs and resultant treatment discontinuation due to failure. Acknowledgements: This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Reinforcement of Postdoctoral Researchers - 2nd Cycle” (MIS-5033021), implemented by the State Scholarships Foundation (ΙΚΥ). Disclosure of Interests: None declared