RESUMEN
INTRODUCTION: Baricitinib is an oral Janus kinase (JAK)1/JAK2 inhibitor approved to treat rheumatoid arthritis (RA). This study aimed to investigate patients' characteristics, prescription patterns, effectiveness, and treatment persistence in patients receiving baricitinib in real-world practice in Spain. METHODS: This retrospective longitudinal cohort study conducted in five rheumatology units included adults with RA initiating baricitinib (Sep-2017-May-19) with at least a 6-month-follow-up. Demographic/clinical characteristics, prescription patterns, and changes in disease activity and pain level were collected until treatment discontinuation/end of follow-up. Treatment persistence was estimated by Kaplan-Meier methods. RESULTS: Data from 182 patients were included (mean (SD)): 83.5% women, 62.2 (12.3) years, body mass index 26.8 (5.1), disease duration 13.2 (10.8) years and Charlson Comorbidity Index score 2.4 (2.0). All patients had received at least one conventional synthetic disease-modifying anti-rheumatic drugs (csDMARD) before starting baricitinib and 78.0% at least one biologic disease-modifying anti-rheumatic drugs (bDMARD). Furthermore, 90.1% started with baricitinib 4 mg/day; 43.4% in monotherapy. One hundred and twelve (61.5%) of patients continued baricitinib at data collection time; mean persistence was 14.1 (0.5) months. Overall treatment persistence was 79.7/64.8/59.1% at 6/12/18 months. Seventy (38.5%) patients discontinued baricitinib during follow-up due to loss of efficacy (68.6%) or adverse events (18.6%). In those patients with available scores at the different observed cut-off points, remission or low disease activity was reported in 71.6 and 76.3% of patients at 6/12 months at any index: Disease Activity Score 28 joints using erythrocyte sedimentation rate (DAS28-ESR) (73.1 and 73.5%), Simplified Disease Activity Index (SDAI) (62.4 and 75.0%), and Clinical Disease Activity Index (CDAI) (66.7 and 78.1%). Good or moderate European League Against Rheumatism (EULAR)-response was noted in 80.0 and 78.2% of patients, respectively. Improvement from baseline in pain (Visual Analog Scale) was 2.5 cm and 3.0 cm at 6/12 months, respectively. CONCLUSIONS: This Spanish cohort of patients treated with baricitinib had a long-standing and refractory disease. Nevertheless, high persistence and improvements in disease activity and pain were found at 6 and 12 months after treatment initiation, independently of the composite disease activity measure used, reinforcing the effectiveness of baricitinib in routine clinical practice.