Background and importance Abatacept (ABA) is a soluble fusion protein consisting of the extracellular domain of human CTLA-4 linked to a modified Fc portion of human IgG1, used in rheumatoid arthritis (RA) in patients with an inadequate or unsustained response to tumour necrosis factor inhibitors (TNFi).

Aim and objectives The aim of this study was to investigate the effectiveness and safety of ABA at 12 months in patients diagnosed with RA.

Material and methods A retrospective cohort study was conducted in patients diagnosed with RA treated with ABA between 2009 and 2019. Sociodemographic, clinical and pharmacological characteristics of the patients were collected. The influence of clinical parameters on ABA effectiveness was evaluated by applied linear or logistic regression models. Effectiveness was measured according to the European League Against Rheumatism (EULAR) response (satisfactory or unsatisfactory), after 12 months of therapy in RA patients. Safety was assessed by adverse events.

Results 171 RA patients were evaluated, 74.27% women (127/171) and age at the start of ABA was 58.40±13.60 years. Administration of ABA was intravenous (iv) in 61.4% (105/171) of patients. Concomitant glucocorticoids were administrated in 84.21% (144/171) of cases and disease modifying antirheumatic drugs (methotrexate or leflunomide) in 50.87% (87/171) of patients. Rheumatoid factor was positive in 78.36% (134/171) of patients and cyclic citrullinated peptide antibodies in 72.51% (124/171). 75.44% of patients had been treated previously with anti-TNF biologics and only 24.56% were naïve for BT. EULAR response after 12 months of ABA treatment was satisfactory in 48.94% (69/141) of patients. Clinical remission (DAS 28 <2.6) at 12 months was 28.37%. Bivariate analysis revealed a higher EULAR response in patients with a lower HAQ score (OR=0.22; 95% CI 0.06 to 0.66; p=0.012), EVA (OR=0.94; 95% CI 0.89 to 0.98; p=0.014) and lower DAS 28 score (OR=0.45; 95% CI 0.20 to 0.84; p=0.025) at the beginning. The incidence of adverse events was 12.87% and 7.8% after 6 and 12 months, respectively. 26.90% stopped ABA before 6 months due to ineffectiveness and 71.63% continued the therapy after 12 months.

Conclusion and relevance In conclusion, ABA exhibited good effectiveness and safety in RA patients, some of whom had failed to respond to previous TNFi treatment.

Conflict of interest No conflict of interest