OP0299 IN RHEUMATOID ARTHRITIS PATIENTS HIGHER NUMBER OF COMORBIDITIES PREDICTS 6-MONTH INSUFFICIENT RESPONSE TO FIRST BIOLOGIC THERAPY AND EVENTUAL CATEGORIZATION OF THE DISEASE AS DIFFICULT-TO-TREAT
Authors: I. Flouri, A. Repa, N. Avgustidis, N. Kougkas, A. Eskitzis, A. Molla Ismail Sali, S. Pitsigavdaki, K. Pateromichelaki, E. Kalogiannaki, M. Terizaki, G. Bertsias, P. Sidiropoulos
Journal: Annals of the Rheumatic Diseases (2021)

Background: Difficult-to-treat rheumatoid arthritis (D2T RA) was recently defined by a EULAR study group (1) and, as a disease category it is largely complicated and under-researched. Patient comorbidities may play a significant role in the response to therapy with biologic disease-modifying antirheumatic drugs (bDMARDs) and in the disease classification as D2T RA. Objectives: To evaluate the impact of comorbidities [studied as total Comorbidities Count (CC) and rheumatic disease comorbidity index (RDCI)] on 6-month response to therapy with the first bDMARD in real-world clinical practice and on eventual disease designation as D2T RA. Methods: Prospective study of all RA patients who start any 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. Response to therapy was defined as achievement of low disease activity or remission (LDA/Rem) according to simplified disease activity index (SDAI) and health assessment questionnaire (HAQ) improvement of ≥ 0.25. D2T RA patient group was defined according to the EULAR definition of D2T RA and was compared to: a/ all other patients and b/ to a sub-group of patients designated as “well-controlled RA” (follow-up ≥2 years and ≥2 visits in the last year in LDA/Rem). Logistic regression models were used to adjust for the potential confounding of age, sex, disease duration, seropositivity, number of previous synthetic DMARDs, type of 1 st bDMARD initiated (TNF inhibitor vs. non-TNF inhibitor), co-administered methotrexate and corticosteroids (yes/no), baseline SDAI and HAQ and year of therapy start. Results: Analysis included 501 RA patients who received a total of 1098 bDMARD treatments. At 1 st bDMARD treatment start, patients (women: 81%) had a median (IQR) age: 60 (51-68) years, disease duration: 5.4 (3-11) years, SDAI: 36 (28-46), HAQ: 1.0 (0.5-1.5), CC: 3 (2-6) και RDCI: 2 (0-3). In adjusted analyses, total comorbidity count (CC) ≤1 (vs ≥ 2) was predicting LDA/Rem at 6 months of therapy [OR (95%CI) = 4.1 (1.5-11), p=0.005], while RDCI=0 (vs. ≥ 1) was predicting HAQ improvement ≥ 0.25 [OR (95% CI) = 2.6 (1.2-6.7), p=0.046]. During 2614 patient-years of follow-up, the disease in 98 patients could be classified as “D2T RA”, while 127 patients had “well-controlled RA”. Baseline independent predictors for D2T RA compared to all other patients were RDCI ≥ 1 (vs. 0) [OR = 3.3 (1.7-9.4), p = 0.024], female sex [OR =3.1 (1.01-9.5)] and age [OR = 0.97 (0.94-0.99)]. Multivariable analyses for predictors of “D2T” compared to “well-controlled” RA yielded similar results. Conclusion: In RA patients starting the first bDMARD treatment, a higher number of comorbidities at baseline is an independent predictor of lower 6-month response to therapy and final disease classification as “difficult-to-treat” RA. References: [1]Nagy G, Roodenrijs NM, Welsing PM, Kedves M, Hamar A, van der Goes MC, et al. EULAR definition of difficult-to-treat rheumatoid arthritis. Ann Rheum Dis. 2021 Jan;80(1):31–5. Acknowledgements: Pancretan Health Association and Special Account for Research Grants (ELKE) – University of Crete. Disclosure of Interests: None declared.