POS0222 ASDAS RESPONSES IN PATIENTS WITH AXIAL SPONDYLOARTHRITIS STARTING BDMARDS: RESULTS FROM A MULTICENTRE PROSPECTIVE COHORT
Authors: M. E. Santos, S. Ramiro, D. Van der Heijde, R. Landewé, F. Pimentel-Santos, A. R. Cruz-Machado, C. Ferreira, C. Gomes, C. Dantas Soares, C. Miguel, F. Albuquerque, F. Martins, L. Silva, H. Santos, I. Almeida, M. Bernardes, N. Khmelinskii, P. Valente, P. M. Teixeira, S. Emídio Matias, V. Fraga, J. C. Branco, A. Sepriano
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> The use of an improvement in the axial spondyloarthritis disease activity score (ASDAS) ≥ 1.1 at 12 weeks is recommended by ASAS to guide the decision of whether treatment with a biological disease-modifying antirheumatic drug (bDMARD) should be continued or not.[1] Many, however, still think that improvements may occur after this timepoint and we do not know whether the (time to) response is influenced by patients' characteristics. <h3>Objectives:</h3> We aimed to assess the likelihood of fulfilling the ASAS criteria for treatment continuation at 3 and 6 months after the start of a bDMARD and whether there are patient characteristics that influence this response. <h3>Methods:</h3> Patients with a diagnosis of axSpA, according to their treating rheumatologist, from the Portuguese national registry of rheumatic diseases (Reuma.PT) who started the first bDMARD from 1<sup>st</sup> of January 2011 to 1<sup>st</sup> of June 2022 were included. To be included, patients were required to have complete data on ASDAS in the following 3 visits: T0 (baseline visit at the start of the bDMARD), T1 (3 months) and T2 (6 months). We determined how many patients fulfilled the ASAS criteria of treatment continuation (Δ ASDAS ≥ 1.1 compared with baseline) at T1 and T2. Patient characteristics (e.g., age, sex, ethnicity, BMI, smoking status) were compared across four groups of patients based on their response: no response in both visits, response only at T1, response only at T2 and response in both visits. If one or more relevant differences were found, the response at T1 and T2 was then evaluated in the subgroups defined by these characteristics. <h3>Results:</h3> In total, 336 patients with axSpA [male: 56%; mean (standard deviation) age: 43 (SD 12)] were included. After 3 months, 199 (58%) patients fulfilled the ASAS criteria of treatment continuation (Table 1). This number was similar at 6 months (N=207; 60%). One hundred and eleven (36%) patients had no ASDAS response in both visits, 28 (8%) responded only at T1, 36 (10%) only at T2, and half of the patients responded in both visits (N=171; 50%). The four groups were mostly comparable except for sex and age. Patients who responded at both visits were more often male (65% vs 45%) and somewhat younger (mean age: 42 vs 45) compared with those who never responded. Similar to the entire population, there were no meaningful differences in the likelihood of response at T1 and T2 across subgroups stratified by age and sex (Table 2). The analysis of response across subgroups also revealed that young male patients had the highest likelihood of response to bDMARDs (T1:73%; T2: 75%), while female patients were less likely to respond irrespective of their age (Table 2). <h3>Conclusion:</h3> The likelihood of a delayed response (beyond 3 months) is very low, which should prompt questioning whether is justified to wait for 6 months to decide on the continuation of the bDMARD treatment. Young male patients are more likely to respond than female patients. Clinicians should keep in mind that diagnostic re-evaluations and addressing comorbidities are as important in the management of axSpA, as choosing the appropriate anti-inflammatory drug. <h3>REFERENCES:</h3> [1] S. Ramiro <i>et al. Ann Rheum Dis</i>. 2023. <h3>Acknowledgements:</h3> Mariana Diz Lopes; Inês Santos; Bárbara Lobão; Joana Borges; Alice Castro; Sandra Sousa; Cláudia Oliveira; Susana P Silva; Ana Rita Fonseca; Diana Gonçalves; Ana Margarida Correia; Paulo Pereira; Marcelo Neto; Mariana Luís; Maria Pontes Ferreira; Anita Cunha; Maura Couto; Vítor Teixeira; Ana Lúcia Fernandes; Patrícia Nero; Filipe Barcelos; Daniel Melim; João Madruga Dias; Jorge Cantante Garcia; Cristina Catita; Tiago Meirinhos; Marlene Sousa; Susana Fernandes; Filipe Cunha Santos; Sara Dinis; Filipe C. Araújo; Tiago Costa; Sandra Falcão; Filipe Barcelos; Cândida Silva; José Tavares-Costa; Margarida Cruz; Filipa Ramos; Ana Valido; Marília Rodrigues; Margarida Mateus; Carlos Vaz; José Marona; Sandra Sousa; Filipa Farinha; Graça Sequeira; Joana Dinis; Elsa Sousa; Pedro Ávila Ribeiro. <h3>Disclosure of Interests:</h3> <b>None declared.</b>