ABS0658 COMPARISON OF BARICITINIB AND TOFACITINIB EFFECTIVENESS IN RHEUMATOID ARTHRITIS: INSIGHTS FROM A REAL-WORLD COHORT USING PROPENSITY SCORE ADJUSTMENTS

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Background: Rheumatoid arthritis (RA) is a chronic, progressive autoimmune disease requiring effective, long-term treatments to prevent structural damage and improve quality of life. Janus Kinase inhibitors (JAKi), including baricitinib and tofacitinib, represent innovative therapies. While randomized clinical trials (RCTs) are the gold standard for assessing efficacy, real-world studies provide critical insights into the effectiveness and safety of treatments in routine clinical practice. However, Observational studies (OS) are susceptible to bias due to imbalances in baseline characteristics between treatment groups. Advanced statistical methods, such as Propensity Score (PS)-based techniques, offer solutions to reduce confounding and provide reliable estimates of treatment effects in OS. Objectives: The main objective of this study is to compare the effectiveness of bariticinib and tofacitinib in patients with RA treated in real clinical practice, adjusting covariables with PS techniques. The secondary objectives are (a) analyzing basal characteristics of the cohort and assessing possible disbalances between treatment groups before statistical adjustment, (b) implementing and comparing PS Matching (PSM) and Inverse Probability Weighting (IPW) methodologies to adjust covariables and minimize the selection bias of the cohort, and (c) estimate and compare measures of treatment effect (Odds Ratio, OR). Methods: Observational, retrospective, multicenter study of a cohort of N=211 RA patients treated with tofacitinib (N=94) or baricitinib (N=117) and followed up in n=14 Rheumatology Services, members of the RA Working Group (GT-ARCat) of the Catalan Society of Rheumatology (SCR). Data were included for patients who underwent JAKi between May 2014 and November 2022. Epidemiological and clinical variables were collected from baseline (W0) to week 52 (W52) of treatment. Analysis of the use of a first JAKi has been performed. To minimize selection bias inherent to observational data, two PS-based methods were applied: PSM and IPW. Firstly, PS were estimated using a logistic regression adjusted with all covariates observed/measured. Then, covariates were balanced through matching the patients of both groups depending on their PS (with PSM), through nearest neighbor matching method with a 1:1 ratio and a caliper of 0.2 times the standard deviation of the logit (PS), or weighting subjects with the inverse probability of receiving the treatment the participant received (with IPW). The best outcome model of each method was chosen comparing the AIC values in order to assess the treatment failure (odds ratio, OR). Only variables with less than 5% missing data were included in the analysis, and the final dataset was restricted to complete cases. Results: Baseline characteristics of the cohort, are detailed in Table 1. Both PSM and IPW achieved improved balance of baseline covariates between the baricitinib and tofacitinib groups. The PSM methodology reduced the sample by around 37%, excluding patients with extreme PS values. In contrast, with IPW, the entire sample was maintained, and weights trimming at the 95 th percentile improved the effective sample size. Odds ratios of covariables obtained with both methodologies are detailed in Table 2. Overall, no major differences in effectiveness were found between baricitinib and tofacitinib. However, under IPW (particularly trimming extreme weights at percentile 95), baricitinib was associated with lower probability of treatment failure (OR=0.542, p=0.038). Pulmonary disease no related to RA and age were consistently statistically associated with treatment failure, the first one linked to an increased probability of JAKi failure (OR>1), and the second one to a slightly decreased probability of treatment failure (OR ~ 0.9). Furthermore, under IPW, male sex, no smoking, not suffering from diabetes, degenerative articular disease, herpes zoster infection, receiving an anti-IL6 previously and the absence of combination with other DMARD were consistently linked to an increased probability of failure. Conclusion: The use of advanced PS techniques, PSM and IPW, allowed a more robust comparison of baricitinib and tofacitinib in real-world clinical practice, suggesting generally similar efficacy with minor discrepancies depending on the methodology. These findings highlight the utility of these techniques in addressing imbalances in confounding variables and mitigating bias in observational studies, emphasizing the need for larger and longer-term studies to validate these observations. REFERENCES: NIL . Acknowledgements: We would like to thank all the members of the AR-Cat group for their involvement in the study and data collection, Mariona Colom for her statistical analysis, and especially the patients who gave their consent to participate. Disclosure of Interests: María América López Lasanta UCB, Pfizer, Abbvie, Mariona Colom Saborit: None declared , Helena Borrell Paños: None declared , Meritxell Sallés Lizarzaburu: None declared , Virginia Ruiz-Esquide: None declared , Daniel Roig Vilaseca: None declared , Annika Nack bvie, jansen, msd, amgen, Carolina Perez-Garcia: None declared , Julia Bernardez: None declared , Andrea Garcia Guillen: None declared , Joana Rovira Aguilar: None declared , Andrea Cuervo: None declared , Marta Valls: None declared , Carmen García Gomez: None declared , Sonia Mínguez: None declared , Rosa Morlà Novell: None declared , Paula Estrada Alarcón: None declared , Melania Martínez-Morillo: None declared , Concepcion Pitarch Grau: None declared , Noemí Busquets-Pérez: None declared , Hye Sang Park: None declared , José A Gómez-Puerta: None declared , Susana Holgado Pérez Astra Zeneca, Gsk, Janssen, Lilly, Pfizer, Otsuka, Sanofi, Nuria Montala Palau: None declared , Raimon Sanmarti Pfizer, Abbvie, MSD, BMS, Gebro-Pharma,Lilly,Sanofi, Roche,Adacyte, BMS, Pfizer, Abbvie,Lilly,Sanofi,Roche,Gebro-Pharma, Lourdes Mateo-Soria Pfizer, Janssen, Abbvie, Cesar Diaz-Torne: None declared , Hèctor Corominas UCB, Pfizer, Novartis, Abbvie,Roche,Gebro-Pharma, Georgina Salvador Alarcon: None declared . © The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.

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