Background: The Tool for Administrative Reimbursement Drug Information Sharing (TARDIS) is an electronic platform combining data collection from all Belgian patients with Rheumatoid Arthritis (RA) on advanced therapy, together with a drug reimbursement request. Therapy choice after initial 2 classical synthetic DMARD failure is left to the treating rheumatologist in Belgium. Objectives: To investigate first-line therapy choices for tumor necrosis factor inhibitor (TNFi) biologic (b) DMARDs, non-TNFi bDMARDs or targeted synthetic (ts) DMARDs via patient characteristics and initial treatment response in the TARDIS-RA registry. Methods: All Belgian rheumatologist inserted patient data online when prescribing a b/tsDMARD. When data was entered for the first time, previous and current use of DMARD therapies was registered. Every next bDMARD or tsDMARD initiation, prolongation and discontinuation was registered electronically. First prolongation is 6 months for bDMARDs and 12 weeks for tsDMARDs, and yearly thereafter. Patients were selected for this analysis if they started a TNFi, non-TNFi or tsDMARD therapy between Jan 2018 and Jan 2019. Rituximab was excluded. Baseline characteristics of bionaive patients per therapy were compared with Mann-Whitney U or Chi 2 tests were appropriate. Regression analyses, adjusted for age, DAS28 baseline and disease duration, evaluated DAS28 change, remission (DAS28<2.6) and low disease activity (LDA, DAS28<3.2) between b/tsDMARDs at first TARDIS follow-up. Results: In 2018, 1263 bionaive RA patients were included. Table 1 describes this population. Time until 1 st follow-up differed between groups with 183 (181-184) days for bDMARD versus 84 (84-84) days for tsDMARD patients. Lineair regression showed an effect of therapy type on DAS28 change in bionaive patients (p=0.017). Logistic regression showed no difference per therapy for remission (p=0.090) nor low disease activity (p=0.123). Proportions of therapy prolongations at 1 st follow up visit did not differ per therapy type. ...